research project
CHAPTER ONE
CHAPTER ONE
1.0
INTRODUCTION
1.1
Background
information.
Stream
flow data is very important information to hydrologists and engineers. This
data is required for managing reservoir release, flow forecast, scheduling
water withdrawals for irrigation and design of hydraulic structures.
The
main techniques used to measure or determine stream flow available are tasking.
Currently stream flow can be determined
using
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Contact
techniques
Non-contact
technique.
This
project is intended to solve the tedious, cumbersome task of visiting the
stream in order to obtain data. It will be a time effective, cost effective,
and user friendly.
It
will be an electronic stream flow measurement intended to relay the stream data
at the office. The machine will apply the relationship of flow discharge and
the height of water level.
It
will consist of floater that is connected to potentiometer through a gear
system. The potentiometer then converts the height variation to an electrical
signal, the electrical signal is transmitted to a data converter which
processes the data conveyed to it to a flow discharge using the Francis formula
for discharge for rectangular cross section.
Rectangular
cross section formula
The
discharge processed will be relayed to a nearby station using a data cable.
Importance of river gauging information.
The
data is used to determine water withdrawal in the river.
The
data is used to predict heavy storms and flooding in a stream.
Statement
of the problem
There are various existing devices designed for the
for determination of stream flow discharge ie the price cup current meters,
solvent method, boat and wading method. These methods exhibit several
challenges in the success of estimation of stream flow data. For instance the
use of current meter require an observer at the stream,
Existing methods does not provide real time data.
The devices are tedious ta carry from the station to
the stream and also processing the data.
It is also risk when wading across the stream while
taking the data.
Due to these challenges there arises the need to
develop a devices that provides a better solution for the determination for
steam flow.
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Objective
To
design and fabricate an efficient real time stream flow data electronic device.
Specific objectives
To design the electronic river flow
measuring device.
To
fabricate the electronic river flow measuring device.
To
test the performance of the device
To
validate the electronic river flow measuring device.
To
calibrate the electronic river flow measuring device.
Justification
Our
project design aims at improving the current existing status of stream flow
measurement by providing a real time data that does not require an observer at
the point and transmit data to a distance upto300metres from the stre
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CHAPTER TWO
2.0
LITERATURE REVIEW
Many types and makes of stream flow measuring
devices are available for use in taking velocity measurements and making
discharge measurements. How well these devices
work under varying and adverse conditions has been a concern since the beginning
of their widespread use for velocity, height and discharge measurements. How
well the current meters in use around the world today work under varying conditions
is of concern to the U.S. Geological Survey (USGS).
The development of new
instrumentation technology, such as the acoustic and electromagnetic
current meters, and renewed
interest in the performance of older instrumentation prompted the USGS in 1990
to create a committee to investigate current meters. As part of the initial
investigations, the
committee performed two tasks: a
review of literature from previous current meter studies and a survey of the
characteristics of discharge measurements made by the USGS.
Literature covering the history
of current-meter design and use includes works by Murphy (1904), Hoyt (1910),
Kolupaila (1960), and Frazier (1967 and 1974). Papers that contain extensive
lists of references covering current-meter testing include Kolupaila (1961),
Dickinson (1967), and Pelletier
(1988). These works are mentioned
because the reader may be interested in aspects of current meters
other than the testing of meters.
MECHANICAL CURRENT
METERS
Mechanical current meters fall
into two categories, vertical-axis current meters and horizontal-axis
current meters. Both of these
meter types use mechanical means to determine the water velocity. Common
examples of the mechanical current meters are the Price-type meter, a
vertical-axis meter, and the Ott-type meter, a horizontal-axis meter
Vertical-Axis Meters
Themeter associated with the
vertical-axis label is the Price-type current meter. Some of the early testing of
vertical-axis meters include meters other than the Price-type.
The Price type current meters
used in the testing outlined in this section fall into three general size categories.
These are the large Price meter with a 7.5 in. (190.5 mm) diameter rotor with 5
cups, the
small Price type meter (including
the present version of this meter) with a 5 in. (127 mm) diameter rotor with 6
cups, and a Price pygmy meter with a 2 in(51 mm) diameter rotor with 6 cups.
Oblique Flows
The concern about the effects of
oblique flows on the performance of the vertical-axis current meter has been
around for quite some time. The earliest documented study located in the USGS
literature
review was in 1899 (Newell, 1899)
where the effects of vertical oblique flows on the calibration of a Price meter
were determined. Because a vertical-axis meter will respond differently to
oblique flows in the vertical and horizontal planes, tests using the two types
of oblique flows will be addressed separately.
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Vertical Oblique Flows
The testing of vertical-axis
current meters subjected to oblique flows in the vertical direction can
generally be lumped into two
groups. The first group of tests are those where the meter is fixed at a
vertical angle and is then towed or placed in flowing water to determine the
meter's performance. This method was used by the Newell (1899), Brown and
Nagler (1914), Scobey (1914), Yarnell and Nagler (1931), Nagler (1931), Rohwer
(1933), Hjalmarson (1967), Engel and DeZeeuw (1979), and Fulford (1990). The second
group of tests are those where the meter is moved vertically when it is being
towed or placed in flowing water. This method was used by Lippincott (1902),
Miller (1902), Groat (1913 and 1916), Scobey (1914), Leach (1931), Rohwer
(1933), Chappell (1939), Kallio (1966a), Thibodeaux and Futrell (1987), Engel
(1990), and Fulford (1990).
The results of tests using the
first method are presented in the Nineteenth Annual Report of the U.S. Geological
Survey (Newell, 1899). This work determines the effects of not holding the
meter in a vertical position when taking discharge measurements. Without giving
the type of meter used in the tests, large Price meter or small Price meter,
the results presented are calibration curves for the meter
tilted at various angles. A table
derived from the calibration curves is also presented for tilt angles of 5, 15,
25, 35, and 45 degrees. No analysis of the data is presented in the report. Brown
and Nagler (1914) present the results of tests on a large Price meter. The
meter was mounted on an assembly that would rotate in the vertical direction around
the meter rotor's center. Little information is given on the testing. The
information that is given covers the test setup. The meter was tested in a
42-inch diameter (1.1 m) pipe flowing partially full, the depth of flow was
kept at approximately
13 in. (0.3 m) deep with a
velocity of 4 ft/s (1.2m/s).
During the tests the meter was
rotated to angles of ±90 degrees. No quantitative results are given in the paper;
but, from the description of the test setup, the results were affected by the
proximity of the meter to the invert of the pipe and the water surface.
The work reported on by Scobey
(1914) consists, in part, of the results of tests on a small Price meter tilted
at angles of ±5, 15, and 30 degrees and towed in a flume. The results are
presented in graphical form with the results of 13 experiments on 1 graph. With
the exception of a few data points, the
graph is too cluttered to be of
much value. As part of an extensive set of tests, Yarnell and Nagler (1931)
conducted vertical oblique flow tests on three types of vertical-axis meters; a
small Price,
Mechanical Current
Meters
An acoustic Price, and the
USGS-improved Price(later designated as the 622-type meter). These tests were
conducted in a flowing flume for meter angles ranging to ±30 degrees in
5-degree increments. The results of the tests are presented graphically where the
meter outputs are plotted against a theoretical cosine response. This is the
first paper to present the results in a manner in which the meter's registered velocity
is plotted against the theoretical cosine response line. For angles producing
an upward current on the meters, all three meters registered less than the
theoretical response. For angles producing a downward current on the meters,
the small Price meter underregistered, the USGS-improved Price meter overregistered;
and the acoustic Price meter fluctuated between overregistering at angles less
than 20 degrees and underregistering at angles greater than 20 degrees. The
authors contend that, at the time of the tests (1931), the Price-type meters
were as good as could be used.
The paper by Yarnell and Nagler is
an extensive collection of discussion letters by other people. Most of these
discussions are comments about the work done by Yarnell and Nagler with a few presenting
results of their own experiments.
The discussion by Nagler (1931)
is one that covers the results of experiments on various meters including a
large Price meter and a small Price meter. These tests were conducted in a pipe
flowing partially full in the same manner as the tests described by Brown and
Nagler (1914). The results are presented in graphical form and are of little
value because of the difficulty in interpreting the data.
In his paper, Rohwer (1933) presents
the results of a comprehensive set of tests to determine the flow measuring characteristics
of most of the current meters available in the United States in the late
1920's. A portion of the testing
conducted in a tangential (straight) tow tank covered vertical oblique flows
for vertical-axis meters. The results presented by Rohwer are in graphical form
and consist of three plots for the small Price meters used.
The plots presenting the data are
arranged so that the number of revolutions of the meter's rotor per foot of
travel is plotted against the tow vehicle's speed; the percent error between
the meter's registered velocity and the axial velocity is plotted against the
angle of the approaching flow (meter tilt angle); and the percent error between
the meter's registered velocity and the cosine of the axial velocity is plotted
against the angle of the approaching flow.
Testing of the present
incarnation of the Pricetype meter, the 622AA-type or just Price type AA, are
reported on by Hjalmarson (1967), Engel and DeZeeuw (1979) and Fulford (1990).
In his article, Hjalmarson briefly presents the results of a test where a Price
type AA meter was rotated at various vertical angles ranging from 0 to 90
degrees in a stream flowing at 0.4 ft/s (0.12 m/s). The results,shown
graphically, indicate that for angles of 20 degrees or less, the meter tested
deviated little from the theoretical cosine response. Engel and DeZeeuw (1979)
tilt the Price type
AA meter they tested in a
vertical plane. The meter was tilted to angles of ±5, 10 and 15 degrees and towed
at velocities ranging from 0.06 m/s (0.20 ft/s) to 3.0 m/s (9.8 ft/s). The data
from the tests are presented in both tabular and graphical form.
The tables are presented in three
types. The first type of table gives values for the tow carriage velocity, V0,
and the revolutions per second, N, for all angles tested.
The second type of table gives
the V0 and the meter efficiency, NWO, values for all of the
angles tested.
The third type of table gives the
percent error of the meter response between no angle and turned angles.As with
the tables, there are three types of graphs
presented. The first type of
graph has the V0 plotted against the ratio of TV at various angles to TV
at an angle of zero degrees. The second type of graph has V0 plotted
against the percent error of the meter's response at the tested angles. The
third type of graph has the angle of alignment plotted against the percent error
of the meter response for various velocities.
Tables and graphs for all angles
above and below the horizontal are given.
The work presented by Fulford
(1990) cover Testing where the Price type AA meter with two types of rotors is
subjected to oblique flows by two methods.The first method used falls into the
category of tilting the meter in the vertical plane and then towing the meter.
The meters tested were rotated ±90 degrees in 10-degree increments. Two types
of rotors were used in the testing: the standard open
metal rotor and the solid polymer
rotor. The results are presented graphically and show the characteristic response
of the Price-type meter with the open metal rotor and the solid polymer rotor.
The second method of testing, moving the meter vertically while towing the
meter, will be discussed below.
In his discussion, Lippincott
(1902) gives little information on his tests. Lippincott's tests were conducted
to determine how the discharge measured in a stream with a large Price meter
would differ if the discharge was taken by moving the meter up and down in the
vertical direction in each vertical (integration method). The only information
given is that the meter determined discharge was between
1 percent more to 2.4 percent
less when the meter was moved at a vertical rate of motion of 0.5 ft/s (0.15
m/s) as compared to the discharge obtained with three velocity measurements at
the top, middepth, and bottom of the stream. No actual comparisons of the meter
velocity measurements are given.
In his discussion, Miller (1902)
states that a large Price meter will overregister when rocked in a vertical
direction when placed in a flowing stream. The very brief description of the
testing indicates that a Price meter and a Haskell meter were suspended from a
skiff in a stream with a current between 2 and 3 ft/s (0.6 to 0.9 m/s) and
rocked in the vertical direction a distance of 1 to 2 ft (0.3 to 0.6 m) by rocking
the skiff. No quantitative data are given. Groat (1913 and 1916) discusses
testing on two types of Price current meters, a large Price meter in 1913 and a
small Price meter in 1916. The 1913 tests described by Groat (1913) have the
meter moving in the vertical direction by rocking the boat being used to
calibrate the meter. Without any information on the rate of vertical movement,
Groat states that the large Price meter's rate of rotation increased by 15
percent over the rate of rotation with no vertical oscillations. There are no
quantitative data given in this paper regarding meter testing.
In his second paper, Groat (1916)
briefly describes the testing of a small Price current meter. These tests
consisted, in part, of oscillating the meter in the vertical direction while it
was being towed in a
towing tank. The results are
given in graphical form and show the deviation of the number of revolutions per
foot of travel that the meter's rotor revolves when different vertical
distances and rates of travel are imparted on the meter. Although cluttered,
the figure does show that the small Price meter tested overregistered to
varying degrees when various vertical oscillations were induced on the meter.
In addition to the work done by
Scobey (1914) of tilting a small Price meter in the vertical direction while
towing the meter, he also oscillated, by hand, a meter in the vertical direction
in still water. The results of this test, which covers various rates of
vertical motion, are given in both tabular and graphical form. These results show
that the rotor of the small Price meter tested will rotate in the direction of
normal rotation when the meter is oscillated in the
vertical direction.
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The paper by Leach (1931) is a
discussion paper to the Yarnell and Nagler (1931) paper. In this discussion, Leach
re-presents the data presented by Groat (1916) and Yarnell and Nagler (1931).
Leach replots Groat's data in the graphical form used by Yarnell and Nagler to
determine if the data from the two tests yield the same results. For relative
vertical angles of flow less than 15 degrees, the data from both tests plot
close together. At angles greater than20 degrees, however, the data points from
the two tests diverge. Leach also gives a better description of Groat's test
setup than Groat presented.
As part of an extensive set of
tests on current meters, Rohwer (1933) tested a pair of small Pricemeters in a
tow tank to determine the effect on the ratings of the meters when a constant
vertical motion of 0.25 ft/s (0.08 m/s) was applied. This test was conducted to
simulate taking an integration discharge measurement. The vertical velocity was
obtained by hand cranking the meter mount upwards while the tow vehicle
traveled along the tank. Rohwer presents his data graphically with the data
from five meters and ten calibration runs plotted on the same graph creating a
cluttered plot. In describing the results,
Rohwer points out that the two small
Price meters tested consistently rotated slower, underregistered,
when moving in a combined
vertical and horizontal direction as compared to moving only in a horizontal direction.
The paper by Chappell (1939)
covers testing on a Price meter to
determine what effects vertical motion had on the meter. The vertical motion
induced on the meter was to simulate the vertical motion that may be found when
making boat and cable way discharge measurements. The meter was tested at one
horizontal velocity by raising and lowering the meter a distance of 2 ft (0.6
m) by hand crank at various vertical velocities.
The vertical velocities of the
test ranged from approximately 0.3 ft/s (0.09 m/s) to 2.2 ft/s (0.66 m/s) with
the horizontal velocity of approximately 2.4 ft/s (0.73 m/s). The results are
given graphically with Chappell concluding that for vertical velocities less
than a quarter of the horizontal velocity, the meter's error in registration was
"slight." The graphs show that the Price meter tested underregistered
for vertical velocities by less than a quarter of the horizontal velocity (approximately
15 degrees) and overregistered for vertical velocities larger than one quarter
of the horizontal velocity. Kallio's (1966a) tests, like Chappell's, were conducted
to determine the effects of vertical motion on current meters. The vertical
motion in these tests simulated the bobbing boat and cable way motions.
Two of the three meters tested by
Kallio were the vertical-axis type, a Price standard current meter and a vane-type
current meter (see appendix for photo of vane-type current meter). For the
testing, vertical motion was induced on the meters by manually raising and
lowering the meters a distance of ±0.1 ft (0.03 m) to ±2.0 ft (0.6 m) at
vertical velocities of 0.4 ft/s (0.12 m/s) to 1.5 ft/s (0.46 m/s). The
horizontal velocities were generated by towing the meters through a tow tank
and suspending the meters into a river. Results are given in both tabular and
graphical form. Results of the Price meter tests show that for vertical
velocities less than 40 percent of the horizontal velocity (approximately 20
degrees), the Price meter will usually underregister the true horizontal
velocity. At higher vertical Velocities,
the meter usually overregisters the horizontal velocity to varying degrees.
Results of the tests on the vane-type meter show that this type of meter almost
always overregisters the horizontal velocity when subjected to vertical motion.
Like Chappell (1939) and Kallio
(1966a), Thibodeaux and Futrell (1987) report on vertical motion tests on
current meters. The two meters tested and reported on by Thibodeaux and Futrell
are the Price type AA current meter with a standard metal rotor and Price type
OAA current meter with a solid polymer rotor. (The Price type OAA current meter
is a Price type AA current meter with the cat whisker counting head replaced
with an optic counting head.) The vertical distance traveled during the tests
were 1, 2, 3, and 4 ft (0.3, 0.6, 0.9, and 1.2 m) with vertical velocities of
0.33, 0.66, 1.00, and 1.2 ft/s (0.10, 0.20, 0.31, and 0.37 m/s). All vertical motions
were generated using a hydraulic cylinder for steady motions. The horizontal
velocities were obtained by towing the meter in a tow tank at velocities ranging
from 0 to 8 ft/s (0 to 2.4 m/s). The results of these tests are given in
graphical form and show that for the Price type AA meter, the results are similar
to those obtained by Kallio. For vertical velocities below 40 percent of the
horizontal velocity
(approximately 20 degrees), the
meter underregistered the horizontal velocity. For vertical to horizontal velocity
ratios larger than 40 percent, the meter generally overregistered the
horizontal velocity.
The results of the OAA meter with
polymer rotor tests show that this meter generally always underregistered the
horizontal velocity. Only at very high vertical to horizontal velocity ratios
did the OAA meter not underregister.
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The paper by Engel (1990) covers
mostly the theoretical side of the integration method of determining the
average velocity in a vertical. A group of limited tests with a Price pygmy
type meter in a laboratory flume is also presented. The results from the limited
tests indicate that the vertical velocity a meter should travel during an integration
velocity determination should not exceed the average horizontal velocity
divided by 80.
The second part of the paper by
Fulford (1990), covers the testing of Price type AA meters by moving the meters
in the vertical direction while being towed in a tow tank. The meters were
moved
either up or down by means of a
hydraulically controlled cable reel assembly. The equivalent oblique
angles obtained by this method
were ±40 degrees.
.
Proximity to Boundaries
The testing of vertical-axis
current meters to determine the effect of placing this type of meter in close
proximity to boundaries, whether side, surface, or bottom boundaries, has been
reported on by
Murphy (1902 and 1904), Rumpf
(1914), Scobey (1914), Rohwer (1933), USGS (1933a), Pierce (1941), Kulin (1977),
and Engel (1983). With the exception of the work by Murphy (1902), Kulin (1977),
and Engel (1983), the tests reported by the authors should be considered as
flawed because of the methods used in the testing, the lack of a true reference
velocity, or both. Murphy (1902 and 1904) reports on a set of tests in which he
compared the velocity measurements made with a small Price meter and those made
with a 6-inch (152 mm) cubical float in the upper 1 ft (0.3 m) of an irrigation
canal. Murphy's conclusion is that when a small Price meter is positioned
within
1
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CHAPTER THREE
3.0 METHODOLOGY
3.1 IDEA
The main idea is to design a simple electronic
stream flow measuring device that is able to convert linear height measurement
of the stream to discrete/digital discharge data and convey the real time data
to a station situated approximately 300m from the stream, constructed using locally
available materials.
3.2 Principle of operation
The electronic stream flow measuring device will
comprise of three functional units which are; height detector, potentiometer
data conversion and transmission or display unit.
First a well-developed and mature cross section is selected
for siting the equipment so as to avoid turbulence and destruction of the
device by heavy materials carried by the river
The rod connected to the floater will move along a
guide so as to restrict its movement to vertical motion only.
The height detected by the floater is transmitted
through the connecting rod, to a potentiometer which will convert the
mechanical movement of the floater to digital data, this will be transmitted to
data conversion device which converts the height to discharge using the
rectangular weir equation;
Q=3.33(L-0.2H)*H3/2
Where
Q=Discharge (m3/s)
L=Length of the cross section of weir (m)
H=Height of the weir (m)
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3.3 Embodiment
Parts and
function
Fig 1 side
view
Fig 2 Fig 2 DETAIL VIEW
Figure 3:flow diagram of process of project.
3.4
parts.
Floater. It’s spherical in shape, plastic material
which is very light in weight to allow high sensitivity in variation in height
of water.
Connecting rod: cylindrical metal rod which act as a
rack and a gear teeth which act as a pinion.
The cylindrical rod (rack) drives the larger gear
when it moves up and down as the water level changes.
Connecting rod guide
Smooth metallic material placed at the sides of the
connecting rod so as to guide the connecting rod and restrict its motion to
vertical only.
Gears
Two gears on the same shaft
Made of Light
aluminum material with gear ratio of 2:1
The bigger gear has more teeth its teeth is twice
the smaller gear.
The reduction by the combination of the gears helps
to attain the limited linear size range of the potentiometer
Potentiometer
This is an electronic device that converts the
linear measurement transmitted by the gears into electrical data for conversion
to digital data
How Potentiometer works
A potentiometer is a resistive sensor used to measure linear
displacements as well as rotary motion. In a potentiometer an electrically
conductive wiper slides across a fixed resistive element. A voltage is applied
across the resistive element. Thus a voltage divider circuit is formed. The
output voltage(Vout) is measured as shown in the figure below. The output
voltage is proportional to the distance travelled.
There are two types of potentiometer, linear and rotary
potentiometer. The linear potentiometer has a slide or wiper. The rotary
potentiometer can be a single turn or multi turn.
The important parameters while selecting a potentiometer are
•Operating temperature
•Shock and vibration
•Humidity
•Contamination and seals
•life cycle
•dither
Some of the advantages of the potentiometer are
•Easy to use
•low cost
•High amplitude output
•Proven technology
•Easily available
Some of the disadvantages of the potentiometer are
•Since the wiper is sliding across the resistive element
there is a possibility of friction and wear. Hence the number of operating
cycles are limited.
•Limited bandwidth
•Inertial loading
Some of the applications of the potentiometer are
•Linear displacement measurement
•Rotary displacement measurement
•Volume control
•Brightness control
•Liquid level measurements using floats
3.5 Design
details
Materials
The materials used in our design and fabrication are
diverse it will consist of aluminums, plastic and steel this is because of the availability,
ease of working, cost and availability, resistant to rust.
The parts are
Connecting rod made of aluminum of length 3000mm.
Floater or ball plastic material with diameter of 100mm.
Metal guide made of mild steel plain sheet of length
3000mm.
Six anchor metals made of mild steel each of length
1000mm and diameter of 50mm.
A shaft. Made of steel with diameter of 300mm.
3.6
Technical specifications
a. Two
gears and two racks
Gear ratio 10:1
b. Potentiometer
To convert the linear measurement to electrical data
Length of 200mm
c. Data cable
To transmit data to a nearby station
Length of cable is 300000mm
d. Shaft
To link the gears
Made of steel and diameter of 300mm
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3.6
Calculations
Data used
Calibration equations
The device is calibrated using the rectangular weir equation
/2
Data
from the river (river njoro)
The length
of river cross section =7.0m
Highest
water level during heavy storms
Lowest
water level recorded
m
m
Difference
in water level 
m
m
=
Determination
of the size of gears
In
order to reduce the height variation of water of 
in the river to fit in to the 
potentiometer a gear system is used.
in the river to fit in to the potentiometer a gear system is used.
R=Ratio
rB =radius
of driver.
rB=radius
of the driven.
NB=number
of teeth (driver)
NB=number
of teeth (driven)
Height
of the river is equal to the circumference of the driver gear=2000mm
C=2000mm
Therefore
diameter of the driver is 200mm
Therefore
gear ratio R=
1
3.7 Design
manufacture
Height detection and transmission
The plastic floater will be connected with a
connecting rod which will be in contact with the water, as the height of water
level varies this will be detected by the floater then transmitted through the
connecting rod to the gear system through to the potentiometer.
Data conversion
The potentiometer connected to the connecting rod
will convert the height variations detected by the floater to an electrical
signal. The electrical data will be delivered to the data processing device.
The data processing unit further processes the
electrical signal to a respective discharge using the rectangular weir equation
Q=3.33(L-0 .22H)H3/2 and the
discharge equation Q=AV
Where
Q=Discharge m3/s
L=length of weir m
H=Height of weir m
A=Area of the weir m2
V=velocity of water in the river m/s
Data display
The data already processed in the data conversion
unit will be will be transmitted to the display device which will be displayed in
a form of digital or discrete data on a display.
3.8
Prototype test and validation.
From the
rectangular weir formula for discharge of a river /2
/2
Q=3.33(L-0.2H)*H3/2
Where
Q=Discharge (m3/s)
L=Length of the cross section of weir (m)
H=Height of the weir (m)
3.33 and 0.22 are constants for the equation.
Since Length of river cross section is constant, it
implies that the discharge Q is proportional to height H, hence change in
discharge Q will vary proportionally to the change in height H.
From the
equation (rectangular weir equation) the prototype will be tested with water of
Q =1M3
and a constant length of 3.3m.
Q=3.33(L-0.2H)*H3/2
1=3.33(3.3-0.22H)*H3/2
Introducing logs
Log 1=log 10.989+3/2logH-log 0.66+5/2logH
0=1.04096+3/2logH-(-0.17653)+5/2logH
H=0.4962M
Therefore from the Francis equation we shall expect an increase in height
of the river of 496.166mm when 1m3 of water is added.
CHAPTER FOUR
Table 5: Work Schedule
Activities
|
Jan
|
Feb
|
March
|
April
|
May
|
Literature review
|
|||||
v Feasibility
study
v Design
specifications
v Embodiment
design
|
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Detailed design
v Budgeting
v Sourcing
for materials
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Design for manufacture
v Design
v Fabrication
v Test
v Validation
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Project presentation
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For more follow the link for homework help
CHAPTER FIVE
5.0 PROJECT BUDGET
REFERENCES
Addison, Herbert, 1949, Hydraulic
measurements (2d
ed.): New York, John Wiley &
Sons, Inc., 327 p.
Aiming, Knut, 1967, Measurements
on current meters in
skew and rotating flow:
International Current Meter
Group - Report 28, 20 p.
Appell, G.F., 1978, A review of
the performance of an
acoustic current meter in Proceedings
of a Working
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January 11-13,
1978, University of Delaware,
Newark, Del.: The
National Oceanic and Atmospheric
Administration
and University of Delaware, p.
35-58.
Aubrey, D.G., Spencer, W.D., and
Towbridge, J.H., 1984,
Dynamic response of
electromagnetic current meters:
Woods Hole Oceanographic
Institution Technical
Report Number WHOI-84-20, 150 p.
Aubrey, D.G., Towbridge, J.H.,
and Spencer, W.D., 1984,
Dynamic response of spherical
electromagnetic
current meters: Institute of
Electrical and Electronic
Engineers, p. 242-248.
Bean, H.S., ed., 1971, Fluid
Meters Their theory and
applications, Report of ASME
Research Committee
on fluid meters (6th ed.): New
York, American
Society of Mechanical Engineers,
p. 91-97.
Bivins, L.E., 1976, Turbulence
effects on current
measurement: Coral Gables, Fla.,
M.S. thesis,
University of Miami, 102 p.
Botma, H.C., 1990, The
VEKTOR-AKWA, an acoustic
current meter for use in
3-dimensional dynamic
flows, in Appell, G.F. and
Curtin, T.B., eds.,
Proceedings: IEEE Fourth Working
Conference on
Current Measurement, 1990,
Clinton, Md., Institute
of Electrical and Electronics
Engineers, p. 120-128.
Brown, E.H., and Nagler, F.,
1914, Preliminary report of
current meter investigations, in
Discussion on
Measurement of the velocity of
flowing water, by
Moody, L.F. (1914): Engineers'
Society of Western
Pennsylvania, 1914, Proceedings,
v. 30, no. 5, p. 415-
417.
Bruck, P.J., Jr., 1965, Vertical
velocity curves under ice
a comparison of Price current
meter with vane ice
meter: Water-Resources Bulletin, May
1965, p. 28-
31.
Buchanan, T.J., 1963, Translation
of "Influence of
turbulence on current meter flow
measurements in
free-flowing channel":
Water-Resources Bulletin,
Aug. 1963, p. 18-20.
Burtsev, P.N. and Baryshnikova,
M.M., 1973, The
analysis of the possibilities of
current meter operation
in turbulent streams, in Hydrometry
Proceedings of
the Koblenz Symposium, Paris,
September 1970:
Paris, UNESCO, v. 1, p. 79-85.
Carter, R.W., 1973, Accuracy of
current meter
measurements, in Hydrometry
Proceedings of the
Koblenz Symposium, Paris,
September 1970: Paris,
UNESCO, v. 1, p. 86-98.
Carter, R.W., and Anderson, I.E.,
1963, Accuracy of
current meter measurements:
Journal of the
Hydraulics Division Proceedings
of the American
Society of Civil Engineers, v.
89, no. HY4, p. 105-
115.
Chappell, C.J., 1939, Effect of
vertical movement of
meter on registered velocities:
Water-Resources
Bulletin, Aug. 1939, p. 435-437.
Gushing, Vincent, 1976,
Electromagnetic water current
meter: Oceans '76, Institute of
Electrical and
Electronic Engineers, p. 25C-1,
25C-17.
Derecki, J.A., and Quinn, F.H.,
1987, Use of current
meters for continuous measurement
of flows in large
rivers: Water Resources Research,
v. 29, no. 9,
p. 1751-1756.
Dickinson, W.T., 1967, Accuracy of
discharge
determinations: Colorado State
University
Hydrology Paper 20, 54 p.
Dickman, R.H., 1951, The rating
of water-current meters:
Water Power, v.3, no. 9, p.
330-334, 341.
Dodge, N.A., 1965, Flow
measurements at Columbia
River power plants: Journal of
the Hydraulics
Division Proceedings of the
American Society of
Civil Engineers, v. 91, no. HY2,
p. 125-147.
26 Review of
Literature on the Testing of Point-Velocity Current Meters
Dreher, F.C., 1957, Comparing
velocities by Pygmy
meter and Pitot tube: Water-Resources
Bulletin, Feb.
1957, p. 3-7.
Engel, Peter, 1983, The effect of
transverse velocity
gradients on the performance of
the Price current
meter: Environmental Canada,
National Water
Research Institute, 16 p.
___1990, On the vertical transit
method of determining
the mean velocity in open channel
flow:
Environmental Canada, National
Water Research
Institute, NWIS Contribution
90-133, 24 p., 16 fig.
Engel, P. and DeZeeuw C, 1978,
The effect of horizontal
alignment on the performance of
Price 622AA
current meter: Environmental
Canada, National
Water Research Institute, 14 p.
___1979, The effect of vertical
alignment on the
performance of the Price 622AA
current meter:
Environmental Canada, National
Water Research
Institute, 10 p., 9 fig., 6
tables.
___1980, Performance of the Price
622AA, Ott C-l,
and Marsh-McBirney 201 current
meters at low speed
Environmental Canada, National
Water Research
Institute, Report Number 80-14,
25 p., 4 fig.
Fischer, M. 1966, Versuche iiber
den Einfluss der
turbulenten Stromung auf
hydrometrishe Fliigel durch
Nachahmung der Turbulenz im
Schlepptank
[Experiments on the influence of
turbulence on
propeller current meters by means
of reproducing the
turbulence in the tow tank]:
International Current
Meter Group Report 19, 6 p., 10
fig. [In German.]
Frazier, A.H., 1941, Current
meter, Gettner: Water-
Resources Bulletin, May 1941, p.
94-96.
___1954, Effect of temperature on
the ratings of Pricetype
current meters: Water-Resources
Bulletin, Feb.
1954, p. 11-13.
___1967, William Gunn Price and
the Price current
meter, in Contributions
from the Museum of History
and Technology: United States
National Museum
Bulletin 252, p. 37-68.
___1974, Water current meters in
the Smithsonian
collections of the National
Museum of History and
Technology: Washington, D.C.,
Smithsonian
Institution Press, 95 p.
Fulford, J.M., 1990, Effect of
turbulence on Price AA
meter rotors, in Chang,
H.H. and Hill, J.C., eds.,
Hydraulic Engineering Proceedings
of the 1990
National Conference July 30 -
Aug. 3, 1990, San
Diego: New York, American Society
of Civil
Engineers, p. 909-914.
___1992, Characteristics of U.S.
Geological Survey
discharge measurements for water
year 1990: U.S.
Geological Survey Open-File
Report 92-493, 79 p.
Golden, H.G. and Trotter, I.L.,
1960, Discussion of A
comparison of stream velocity
meters, by F.W.
Townsend and F.A. Blust: Journal
of the Hydraulics
Division Proceedings of the
American Society of
Civil Engineers, v. 86, no. HY9,
p. 155-156.
Griffiths, G., 1979, The effect
of turbulence on the
calibration of electromagnetic
current sensors and an
approximation of their spatial
response: Institute of
Oceanographic Sciences Report No.
68, (unpublished
manuscript), 14 p.
Groat, B.F., 1913,
Characteristics of cup and screw
current meters Performance of
these meters in tailraces
and large mountain streams
Statistical
synthesis of discharge curves,
with discussions:
American Society of Civil
Engineers Transactions,
v. 76, p. 819-870.
___1916, Chemi-hydrometry and its
applications to the
precise testing of hydro-electric
generators, part 5 of
5, with discussions: American
Society of Civil
Engineers Transactions, v. 80, p.
1231-1271.
Grover, N.C., 1931, Discussion
o/Effect of turbulence on
the registration of current
meters, by D.L. Yarnell
and F.A. Nagler, 1931: American
Society of Civil
Engineers Transactions, v. 95, p.
806-811.
Hjalmarson, H.W., 1965, Price
current meter and
instrument characteristics:
Water-Resources Bulletin,
May 1965, p. 20-23.
___1967, Effect of transverse
velocity on the Price
current meter: Water-Resources
Bulletin, April-June
1967, p. 26-27.
Horton, R.E., 1931, Discussion
o/Effect of turbulence on
the registration of current
meters, by D.L. Yarnell
and F.A. Nagler, 1931: American
Society of Civil
Engineers Transactions, v. 95, p.
840-854.
Hoyt, J.C., 1910, The use and
care of the current meter,
as practiced by the United States
Geological Survey,
with discussions: American
Society of Civil
Engineers Transactions, v. 66, p.
70-134.
___1934, Tests of current
velocity meters and their
performance: The Canadian
Engineer, v. 67, no. 17,
p. 3-7.
Jepson, P., 1967, Currentmeter
errors under pulsating
flow conditions: Journal of
Mechanical Engineering
Science, v. 9, no. 1, p. 45-54.
Johnson, R.L., 1966, Laboratory
determination of current
meter performance, Technical
Report No. 843-1:
Bonneville, Oregon, Division
Hydraulic Laboratory,
North Pacific U. S. Army
Engineering Division,
Corps of Engineers, 33 p.
Kallio, N.A., 1966a, Effects of
vertical motion on current
meters: U.S. Geological Survey
Water-Supply Paper
1869-B, 20 p.
References Cited 27
_1966b, Some precautions to the
use of the
component propeller with the Ott
current meter:
Water-Resources Bulletin,
Oct.-Dec. 1966, p. 5-8.
Kolupaila, Steponas, 1949, Recent
developments in
current-meter design:
Transactions of the American
Geophysical Union, v. 30, no. 6,
p. 916-918.
___1958, Use of current meters in
turbulent and
divergent channels in Proceedings
and Reports of the
International Association of
Scientific Hydrology,
General Assembly at Toronto 1957,
Gentbrugge,
1958: Toronto, International
Association of Scientific
Hydrology, p. 437-444.
___1960, Early history of
hydrometry in the United
States: Journal of the Hydraulics
Division
Proceedings of the American
Society of Civil
Engineers, v. 86, no. HY1, p.
1-51.
_1961, Bibliography of
hydrometry: Notre Dame,
Ind, University of Notre Dame
Press, 975 p.
Kulin, Gershon, 1977, Some error
sources in Price and
Pygmy current meter traverses, in
Irwin, Lafayette
K., ed., Flow measurement in open
channels and
closed conduits, v. 1 and 2:
National Bureau of
Standards Special Publication
484, p. 123-144.
Kulin, Gershon, and Compton,
P.R., 1975, A guide to
methods and standards for the
measurement of water
flow: National Bureau of
Standards Special
Publication 421, 89 p.
LaCornu, E.J., Hanson, R.L., and
Gruff, R.W., 1965,
Comparison of discharge
measurements made by
integration- and point-velocity
methods: Water-
Resources Bulletin, Aug. 1965, p.
17-19.
Leach, H.R., 1931, Discussion of
Effect of turbulence on
the registration of current
meters, by D.L. Yarnell
and F. A. Nagler, 1931: American
Society of Civil
Engineers Transactions, v. 95, p.
816-826.
Leonard, R.W., 1965, Discussion
o/Flow measurements
at Columbia River power plants,
by N.A. Dodge,
1965: Journal of the Hydraulics
Division
Proceedings of the American
Society of Civil
Engineers, v. 91, no. HY6, p.
194-200.
Lippincott, J.B., 1902,
Discussion of Current meter and
weir discharge comparisons, by
E.G. Murphy, 1902:
American Society of Civil
Engineers Transactions,
v. 47, p. 383-387.
Marsh-McBirney, 1988, Directional
sensitivity of
oceanographic flow sensors:
Marsh-McBirney
Technical Note 5, 9 p.
McDonald, C.C., 1940,
Salt-velocity method, comparison
with current-meter measurements
and weir formula:
Water-Resources Bulletin, August
1940, p. 147-151.
Mero, Thomas; Appell, Gerald; and
McQuivey, R.S.,
1977, Marine dynamics and its
effects on current
measuring transducers, in Irwin,
L.K., ed., Flow
measurement in open channels and
closed conduits,
v. 1 and 2: National Bureau of
Standards Special
Publication 484, p. 109-122.
Miller, C.H., 1902, Discussion of
Current meter and weir
discharge comparisons, by E.G.
Murphy, 1902:
American Society of Civil Engineers
Transactions,
v. 47, p. 379-380.
Murphy, E.G., 1901, Tests to
determine the accuracy of
discharge measurements of New
York state canals
and feeders, in Operations
at river stations, 1900:
Water-Supply and Irrigation
Papers of the United
States Geological Survey, no. 47,
p. 18-29.
___1902, Current meter and weir
discharge
comparisons, with discussions:
American Society of
Civil Engineers Transactions, v.
47, p. 371-391.
___1904, Accuracy of stream
measurements: Water-
Supply and Irrigation Papers of
the United States
Geological Survey, no. 95.
Nagler, Forrest, 1931, Discussion
of Effect of turbulence
on the registration of current
meters, by D.L. Yarnell
1.0
INTRODUCTION
1.1
Background
information.
Stream
flow data is very important information to hydrologists and engineers. This
data is required for managing reservoir release, flow forecast, scheduling
water withdrawals for irrigation and design of hydraulic structures.
The
main techniques used to measure or determine stream flow available are tasking.
Currently stream flow can be determined using
Contact
techniques
Non-contact
technique.
This
project is intended to solve the tedious, cumbersome task of visiting the
stream in order to obtain data. It will be a time effective, cost effective,
and user friendly.
It
will be an electronic stream flow measurement intended to relay the stream data
at the office. The machine will apply the relationship of flow discharge and
the height of water level.
It
will consist of floater that is connected to potentiometer through a gear
system. The potentiometer then converts the height variation to an electrical
signal, the electrical signal is transmitted to a data converter which
processes the data conveyed to it to a flow discharge using the Francis formula
for discharge for rectangular cross section.
Rectangular
cross section formula
/2
The
discharge processed will be relayed to a nearby station using a data cable.
Importance of river gauging information.
The
data is used to determine water withdrawal in the river.
The
data is used to predict heavy storms and flooding in a stream.
Statement
of the problem
There are various existing devices designed for the
for determination of stream flow discharge ie the price cup current meters,
solvent method, boat and wading method. These methods exhibit several
challenges in the success of estimation of stream flow data. For instance the
use of current meter require an observer at the stream,
Existing methods does not provide real time data.
The devices are tedious ta carry from the station to
the stream and also processing the data.
It is also risk when wading across the stream while
taking the data.
Due to these challenges there arises the need to
develop a devices that provides a better solution for the determination for
steam flow.
Objective
To
design and fabricate an efficient real time stream flow data electronic device.
Specific objectives
To design the electronic river flow
measuring device.
To
fabricate the electronic river flow measuring device.
To
test the performance of the device
To
validate the electronic river flow measuring device.
To
calibrate the electronic river flow measuring device.
Justification
Our
project design aims at improving the current existing status of stream flow
measurement by providing a real time data that does not require an observer at
the point and transmit data to a distance upto300metres from the stre
CHAPTER TWO
2.0
LITERATURE REVIEW
Many types and makes of stream flow measuring
devices are available for use in taking velocity measurements and making
discharge measurements. How well these devices
work under varying and adverse conditions has been a concern since the beginning
of their widespread use for velocity, height and discharge measurements. How
well the current meters in use around the world today work under varying conditions
is of concern to the U.S. Geological Survey (USGS).
The development of new
instrumentation technology, such as the acoustic and electromagnetic
current meters, and renewed
interest in the performance of older instrumentation prompted the USGS in 1990
to create a committee to investigate current meters. As part of the initial
investigations, the
committee performed two tasks: a
review of literature from previous current meter studies and a survey of the
characteristics of discharge measurements made by the USGS.
Literature covering the history
of current-meter design and use includes works by Murphy (1904), Hoyt (1910),
Kolupaila (1960), and Frazier (1967 and 1974). Papers that contain extensive
lists of references covering current-meter testing include Kolupaila (1961),
Dickinson (1967), and Pelletier
(1988). These works are mentioned
because the reader may be interested in aspects of current meters
other than the testing of meters.
MECHANICAL CURRENT
METERS
Mechanical current meters fall
into two categories, vertical-axis current meters and horizontal-axis
current meters. Both of these
meter types use mechanical means to determine the water velocity. Common
examples of the mechanical current meters are the Price-type meter, a
vertical-axis meter, and the Ott-type meter, a horizontal-axis meter
Vertical-Axis Meters
Themeter associated with the
vertical-axis label is the Price-type current meter. Some of the early testing of
vertical-axis meters include meters other than the Price-type.
The Price type current meters
used in the testing outlined in this section fall into three general size categories.
These are the large Price meter with a 7.5 in. (190.5 mm) diameter rotor with 5
cups, the
small Price type meter (including
the present version of this meter) with a 5 in. (127 mm) diameter rotor with 6
cups, and a Price pygmy meter with a 2 in(51 mm) diameter rotor with 6 cups.
Oblique Flows
The concern about the effects of
oblique flows on the performance of the vertical-axis current meter has been
around for quite some time. The earliest documented study located in the USGS
literature
review was in 1899 (Newell, 1899)
where the effects of vertical oblique flows on the calibration of a Price meter
were determined. Because a vertical-axis meter will respond differently to
oblique flows in the vertical and horizontal planes, tests using the two types
of oblique flows will be addressed separately.
Vertical Oblique Flows
The testing of vertical-axis
current meters subjected to oblique flows in the vertical direction can
generally be lumped into two
groups. The first group of tests are those where the meter is fixed at a
vertical angle and is then towed or placed in flowing water to determine the
meter's performance. This method was used by the Newell (1899), Brown and
Nagler (1914), Scobey (1914), Yarnell and Nagler (1931), Nagler (1931), Rohwer
(1933), Hjalmarson (1967), Engel and DeZeeuw (1979), and Fulford (1990). The second
group of tests are those where the meter is moved vertically when it is being
towed or placed in flowing water. This method was used by Lippincott (1902),
Miller (1902), Groat (1913 and 1916), Scobey (1914), Leach (1931), Rohwer
(1933), Chappell (1939), Kallio (1966a), Thibodeaux and Futrell (1987), Engel
(1990), and Fulford (1990).
The results of tests using the
first method are presented in the Nineteenth Annual Report of the U.S. Geological
Survey (Newell, 1899). This work determines the effects of not holding the
meter in a vertical position when taking discharge measurements. Without giving
the type of meter used in the tests, large Price meter or small Price meter,
the results presented are calibration curves for the meter
tilted at various angles. A table
derived from the calibration curves is also presented for tilt angles of 5, 15,
25, 35, and 45 degrees. No analysis of the data is presented in the report. Brown
and Nagler (1914) present the results of tests on a large Price meter. The
meter was mounted on an assembly that would rotate in the vertical direction around
the meter rotor's center. Little information is given on the testing. The
information that is given covers the test setup. The meter was tested in a
42-inch diameter (1.1 m) pipe flowing partially full, the depth of flow was
kept at approximately
13 in. (0.3 m) deep with a
velocity of 4 ft/s (1.2m/s).
During the tests the meter was
rotated to angles of ±90 degrees. No quantitative results are given in the paper;
but, from the description of the test setup, the results were affected by the
proximity of the meter to the invert of the pipe and the water surface.
The work reported on by Scobey
(1914) consists, in part, of the results of tests on a small Price meter tilted
at angles of ±5, 15, and 30 degrees and towed in a flume. The results are
presented in graphical form with the results of 13 experiments on 1 graph. With
the exception of a few data points, the
graph is too cluttered to be of
much value. As part of an extensive set of tests, Yarnell and Nagler (1931)
conducted vertical oblique flow tests on three types of vertical-axis meters; a
small Price,
Mechanical Current
Meters
An acoustic Price, and the
USGS-improved Price(later designated as the 622-type meter). These tests were
conducted in a flowing flume for meter angles ranging to ±30 degrees in
5-degree increments. The results of the tests are presented graphically where the
meter outputs are plotted against a theoretical cosine response. This is the
first paper to present the results in a manner in which the meter's registered velocity
is plotted against the theoretical cosine response line. For angles producing
an upward current on the meters, all three meters registered less than the
theoretical response. For angles producing a downward current on the meters,
the small Price meter underregistered, the USGS-improved Price meter overregistered;
and the acoustic Price meter fluctuated between overregistering at angles less
than 20 degrees and underregistering at angles greater than 20 degrees. The
authors contend that, at the time of the tests (1931), the Price-type meters
were as good as could be used.
The paper by Yarnell and Nagler is
an extensive collection of discussion letters by other people. Most of these
discussions are comments about the work done by Yarnell and Nagler with a few presenting
results of their own experiments.
The discussion by Nagler (1931)
is one that covers the results of experiments on various meters including a
large Price meter and a small Price meter. These tests were conducted in a pipe
flowing partially full in the same manner as the tests described by Brown and
Nagler (1914). The results are presented in graphical form and are of little
value because of the difficulty in interpreting the data.
In his paper, Rohwer (1933) presents
the results of a comprehensive set of tests to determine the flow measuring characteristics
of most of the current meters available in the United States in the late
1920's. A portion of the testing
conducted in a tangential (straight) tow tank covered vertical oblique flows
for vertical-axis meters. The results presented by Rohwer are in graphical form
and consist of three plots for the small Price meters used.
The plots presenting the data are
arranged so that the number of revolutions of the meter's rotor per foot of
travel is plotted against the tow vehicle's speed; the percent error between
the meter's registered velocity and the axial velocity is plotted against the
angle of the approaching flow (meter tilt angle); and the percent error between
the meter's registered velocity and the cosine of the axial velocity is plotted
against the angle of the approaching flow.
Testing of the present
incarnation of the Pricetype meter, the 622AA-type or just Price type AA, are
reported on by Hjalmarson (1967), Engel and DeZeeuw (1979) and Fulford (1990).
In his article, Hjalmarson briefly presents the results of a test where a Price
type AA meter was rotated at various vertical angles ranging from 0 to 90
degrees in a stream flowing at 0.4 ft/s (0.12 m/s). The results,shown
graphically, indicate that for angles of 20 degrees or less, the meter tested
deviated little from the theoretical cosine response. Engel and DeZeeuw (1979)
tilt the Price type
AA meter they tested in a
vertical plane. The meter was tilted to angles of ±5, 10 and 15 degrees and towed
at velocities ranging from 0.06 m/s (0.20 ft/s) to 3.0 m/s (9.8 ft/s). The data
from the tests are presented in both tabular and graphical form.
The tables are presented in three
types. The first type of table gives values for the tow carriage velocity, V0,
and the revolutions per second, N, for all angles tested.
The second type of table gives
the V0 and the meter efficiency, NWO, values for all of the
angles tested.
The third type of table gives the
percent error of the meter response between no angle and turned angles.As with
the tables, there are three types of graphs
presented. The first type of
graph has the V0 plotted against the ratio of TV at various angles to TV
at an angle of zero degrees. The second type of graph has V0 plotted
against the percent error of the meter's response at the tested angles. The
third type of graph has the angle of alignment plotted against the percent error
of the meter response for various velocities.
Tables and graphs for all angles
above and below the horizontal are given.
The work presented by Fulford
(1990) cover Testing where the Price type AA meter with two types of rotors is
subjected to oblique flows by two methods.The first method used falls into the
category of tilting the meter in the vertical plane and then towing the meter.
The meters tested were rotated ±90 degrees in 10-degree increments. Two types
of rotors were used in the testing: the standard open
metal rotor and the solid polymer
rotor. The results are presented graphically and show the characteristic response
of the Price-type meter with the open metal rotor and the solid polymer rotor.
The second method of testing, moving the meter vertically while towing the
meter, will be discussed below.
In his discussion, Lippincott
(1902) gives little information on his tests. Lippincott's tests were conducted
to determine how the discharge measured in a stream with a large Price meter
would differ if the discharge was taken by moving the meter up and down in the
vertical direction in each vertical (integration method). The only information
given is that the meter determined discharge was between
1 percent more to 2.4 percent
less when the meter was moved at a vertical rate of motion of 0.5 ft/s (0.15
m/s) as compared to the discharge obtained with three velocity measurements at
the top, middepth, and bottom of the stream. No actual comparisons of the meter
velocity measurements are given.
In his discussion, Miller (1902)
states that a large Price meter will overregister when rocked in a vertical
direction when placed in a flowing stream. The very brief description of the
testing indicates that a Price meter and a Haskell meter were suspended from a
skiff in a stream with a current between 2 and 3 ft/s (0.6 to 0.9 m/s) and
rocked in the vertical direction a distance of 1 to 2 ft (0.3 to 0.6 m) by rocking
the skiff. No quantitative data are given. Groat (1913 and 1916) discusses
testing on two types of Price current meters, a large Price meter in 1913 and a
small Price meter in 1916. The 1913 tests described by Groat (1913) have the
meter moving in the vertical direction by rocking the boat being used to
calibrate the meter. Without any information on the rate of vertical movement,
Groat states that the large Price meter's rate of rotation increased by 15
percent over the rate of rotation with no vertical oscillations. There are no
quantitative data given in this paper regarding meter testing.
In his second paper, Groat (1916)
briefly describes the testing of a small Price current meter. These tests
consisted, in part, of oscillating the meter in the vertical direction while it
was being towed in a
towing tank. The results are
given in graphical form and show the deviation of the number of revolutions per
foot of travel that the meter's rotor revolves when different vertical
distances and rates of travel are imparted on the meter. Although cluttered,
the figure does show that the small Price meter tested overregistered to
varying degrees when various vertical oscillations were induced on the meter.
In addition to the work done by
Scobey (1914) of tilting a small Price meter in the vertical direction while
towing the meter, he also oscillated, by hand, a meter in the vertical direction
in still water. The results of this test, which covers various rates of
vertical motion, are given in both tabular and graphical form. These results show
that the rotor of the small Price meter tested will rotate in the direction of
normal rotation when the meter is oscillated in the
vertical direction.
The paper by Leach (1931) is a
discussion paper to the Yarnell and Nagler (1931) paper. In this discussion, Leach
re-presents the data presented by Groat (1916) and Yarnell and Nagler (1931).
Leach replots Groat's data in the graphical form used by Yarnell and Nagler to
determine if the data from the two tests yield the same results. For relative
vertical angles of flow less than 15 degrees, the data from both tests plot
close together. At angles greater than20 degrees, however, the data points from
the two tests diverge. Leach also gives a better description of Groat's test
setup than Groat presented.
As part of an extensive set of
tests on current meters, Rohwer (1933) tested a pair of small Pricemeters in a
tow tank to determine the effect on the ratings of the meters when a constant
vertical motion of 0.25 ft/s (0.08 m/s) was applied. This test was conducted to
simulate taking an integration discharge measurement. The vertical velocity was
obtained by hand cranking the meter mount upwards while the tow vehicle
traveled along the tank. Rohwer presents his data graphically with the data
from five meters and ten calibration runs plotted on the same graph creating a
cluttered plot. In describing the results,
Rohwer points out that the two small
Price meters tested consistently rotated slower, underregistered,
when moving in a combined
vertical and horizontal direction as compared to moving only in a horizontal direction.
The paper by Chappell (1939)
covers testing on a Price meter to
determine what effects vertical motion had on the meter. The vertical motion
induced on the meter was to simulate the vertical motion that may be found when
making boat and cable way discharge measurements. The meter was tested at one
horizontal velocity by raising and lowering the meter a distance of 2 ft (0.6
m) by hand crank at various vertical velocities.
The vertical velocities of the
test ranged from approximately 0.3 ft/s (0.09 m/s) to 2.2 ft/s (0.66 m/s) with
the horizontal velocity of approximately 2.4 ft/s (0.73 m/s). The results are
given graphically with Chappell concluding that for vertical velocities less
than a quarter of the horizontal velocity, the meter's error in registration was
"slight." The graphs show that the Price meter tested underregistered
for vertical velocities by less than a quarter of the horizontal velocity (approximately
15 degrees) and overregistered for vertical velocities larger than one quarter
of the horizontal velocity. Kallio's (1966a) tests, like Chappell's, were conducted
to determine the effects of vertical motion on current meters. The vertical
motion in these tests simulated the bobbing boat and cable way motions.
Two of the three meters tested by
Kallio were the vertical-axis type, a Price standard current meter and a vane-type
current meter (see appendix for photo of vane-type current meter). For the
testing, vertical motion was induced on the meters by manually raising and
lowering the meters a distance of ±0.1 ft (0.03 m) to ±2.0 ft (0.6 m) at
vertical velocities of 0.4 ft/s (0.12 m/s) to 1.5 ft/s (0.46 m/s). The
horizontal velocities were generated by towing the meters through a tow tank
and suspending the meters into a river. Results are given in both tabular and
graphical form. Results of the Price meter tests show that for vertical
velocities less than 40 percent of the horizontal velocity (approximately 20
degrees), the Price meter will usually underregister the true horizontal
velocity. At higher vertical Velocities,
the meter usually overregisters the horizontal velocity to varying degrees.
Results of the tests on the vane-type meter show that this type of meter almost
always overregisters the horizontal velocity when subjected to vertical motion.
Like Chappell (1939) and Kallio
(1966a), Thibodeaux and Futrell (1987) report on vertical motion tests on
current meters. The two meters tested and reported on by Thibodeaux and Futrell
are the Price type AA current meter with a standard metal rotor and Price type
OAA current meter with a solid polymer rotor. (The Price type OAA current meter
is a Price type AA current meter with the cat whisker counting head replaced
with an optic counting head.) The vertical distance traveled during the tests
were 1, 2, 3, and 4 ft (0.3, 0.6, 0.9, and 1.2 m) with vertical velocities of
0.33, 0.66, 1.00, and 1.2 ft/s (0.10, 0.20, 0.31, and 0.37 m/s). All vertical motions
were generated using a hydraulic cylinder for steady motions. The horizontal
velocities were obtained by towing the meter in a tow tank at velocities ranging
from 0 to 8 ft/s (0 to 2.4 m/s). The results of these tests are given in
graphical form and show that for the Price type AA meter, the results are similar
to those obtained by Kallio. For vertical velocities below 40 percent of the
horizontal velocity
(approximately 20 degrees), the
meter underregistered the horizontal velocity. For vertical to horizontal velocity
ratios larger than 40 percent, the meter generally overregistered the
horizontal velocity.
The results of the OAA meter with
polymer rotor tests show that this meter generally always underregistered the
horizontal velocity. Only at very high vertical to horizontal velocity ratios
did the OAA meter not underregister.
The paper by Engel (1990) covers
mostly the theoretical side of the integration method of determining the
average velocity in a vertical. A group of limited tests with a Price pygmy
type meter in a laboratory flume is also presented. The results from the limited
tests indicate that the vertical velocity a meter should travel during an integration
velocity determination should not exceed the average horizontal velocity
divided by 80.
The second part of the paper by
Fulford (1990), covers the testing of Price type AA meters by moving the meters
in the vertical direction while being towed in a tow tank. The meters were
moved
either up or down by means of a
hydraulically controlled cable reel assembly. The equivalent oblique
angles obtained by this method
were ±40 degrees.
.
Proximity to Boundaries
The testing of vertical-axis
current meters to determine the effect of placing this type of meter in close
proximity to boundaries, whether side, surface, or bottom boundaries, has been
reported on by
Murphy (1902 and 1904), Rumpf
(1914), Scobey (1914), Rohwer (1933), USGS (1933a), Pierce (1941), Kulin (1977),
and Engel (1983). With the exception of the work by Murphy (1902), Kulin (1977),
and Engel (1983), the tests reported by the authors should be considered as
flawed because of the methods used in the testing, the lack of a true reference
velocity, or both. Murphy (1902 and 1904) reports on a set of tests in which he
compared the velocity measurements made with a small Price meter and those made
with a 6-inch (152 mm) cubical float in the upper 1 ft (0.3 m) of an irrigation
canal. Murphy's conclusion is that when a small Price meter is positioned
within
1
For more follow the link for homework help
CHAPTER THREE
3.0 METHODOLOGY
3.1 IDEA
The main idea is to design a simple electronic
stream flow measuring device that is able to convert linear height measurement
of the stream to discrete/digital discharge data and convey the real time data
to a station situated approximately 300m from the stream, constructed using locally
available materials.
3.2 Principle of operation
The electronic stream flow measuring device will
comprise of three functional units which are; height detector, potentiometer
data conversion and transmission or display unit.
First a well-developed and mature cross section is selected
for siting the equipment so as to avoid turbulence and destruction of the
device by heavy materials carried by the river
The rod connected to the floater will move along a
guide so as to restrict its movement to vertical motion only.
The height detected by the floater is transmitted
through the connecting rod, to a potentiometer which will convert the
mechanical movement of the floater to digital data, this will be transmitted to
data conversion device which converts the height to discharge using the
rectangular weir equation;
Q=3.33(L-0.2H)*H3/2
Where
Q=Discharge (m3/s)
L=Length of the cross section of weir (m)
H=Height of the weir (m)
3.3 Embodiment
Parts and
function
Fig 1 side
view
Fig 2 Fig 2 DETAIL VIEW
Figure 3:flow diagram of process of project.
3.4
parts.
Floater. It’s spherical in shape, plastic material
which is very light in weight to allow high sensitivity in variation in height
of water.
Connecting rod: cylindrical metal rod which act as a
rack and a gear teeth which act as a pinion.
The cylindrical rod (rack) drives the larger gear
when it moves up and down as the water level changes.
Connecting rod guide
Smooth metallic material placed at the sides of the
connecting rod so as to guide the connecting rod and restrict its motion to
vertical only.
Gears
Two gears on the same shaft
Made of Light
aluminum material with gear ratio of 2:1
The bigger gear has more teeth its teeth is twice
the smaller gear.
The reduction by the combination of the gears helps
to attain the limited linear size range of the potentiometer
Potentiometer
This is an electronic device that converts the
linear measurement transmitted by the gears into electrical data for conversion
to digital data
How Potentiometer works
A potentiometer is a resistive sensor used to measure linear
displacements as well as rotary motion. In a potentiometer an electrically
conductive wiper slides across a fixed resistive element. A voltage is applied
across the resistive element. Thus a voltage divider circuit is formed. The
output voltage(Vout) is measured as shown in the figure below. The output
voltage is proportional to the distance travelled.
There are two types of potentiometer, linear and rotary
potentiometer. The linear potentiometer has a slide or wiper. The rotary
potentiometer can be a single turn or multi turn.
The important parameters while selecting a potentiometer are
•Operating temperature
•Shock and vibration
•Humidity
•Contamination and seals
•life cycle
•dither
Some of the advantages of the potentiometer are
•Easy to use
•low cost
•High amplitude output
•Proven technology
•Easily available
Some of the disadvantages of the potentiometer are
•Since the wiper is sliding across the resistive element
there is a possibility of friction and wear. Hence the number of operating
cycles are limited.
•Limited bandwidth
•Inertial loading
Some of the applications of the potentiometer are
•Linear displacement measurement
•Rotary displacement measurement
•Volume control
•Brightness control
•Liquid level measurements using floats
For more follow the link for homework help
3.5 Design
details
Materials
The materials used in our design and fabrication are
diverse it will consist of aluminums, plastic and steel this is because of the availability,
ease of working, cost and availability, resistant to rust.
The parts are
Connecting rod made of aluminum of length 3000mm.
Floater or ball plastic material with diameter of 100mm.
Metal guide made of mild steel plain sheet of length
3000mm.
Six anchor metals made of mild steel each of length
1000mm and diameter of 50mm.
A shaft. Made of steel with diameter of 300mm.
3.6
Technical specifications
a. Two
gears and two racks
Gear ratio 10:1
b. Potentiometer
To convert the linear measurement to electrical data
Length of 200mm
c. Data cable
To transmit data to a nearby station
Length of cable is 300000mm
d. Shaft
To link the gears
Made of steel and diameter of 300mm
3.6
Calculations
Data used
Calibration equations
The device is calibrated using the rectangular weir equation
/2
Data
from the river (river njoro)
The length
of river cross section =7.0m
Highest
water level during heavy storms
Lowest
water level recordedm
m
Difference
in water level m
m
=
Determination
of the size of gears
In
order to reduce the height variation of water of in the river to fit in to the potentiometer a gear system is used.
in the river to fit in to the potentiometer a gear system is used.
R=Ratio
rB =radius
of driver.
rB=radius
of the driven.
NB=number
of teeth (driver)
NB=number
of teeth (driven)
Height
of the river is equal to the circumference of the driver gear=2000mm
C=2000mm
Therefore
diameter of the driver is 200mm
Therefore
gear ratio R=
1
3.7 Design
manufacture
Height detection and transmission
The plastic floater will be connected with a
connecting rod which will be in contact with the water, as the height of water
level varies this will be detected by the floater then transmitted through the
connecting rod to the gear system through to the potentiometer.
Data conversion
The potentiometer connected to the connecting rod
will convert the height variations detected by the floater to an electrical
signal. The electrical data will be delivered to the data processing device.
The data processing unit further processes the
electrical signal to a respective discharge using the rectangular weir equation
Q=3.33(L-0 .22H)H3/2 and the
discharge equation Q=AV
Where
Q=Discharge m3/s
L=length of weir m
H=Height of weir m
A=Area of the weir m2
V=velocity of water in the river m/s
Data display
The data already processed in the data conversion
unit will be will be transmitted to the display device which will be displayed in
a form of digital or discrete data on a display.
3.8
Prototype test and validation.
From the
rectangular weir formula for discharge of a river /2
/2
Q=3.33(L-0.2H)*H3/2
Where
Q=Discharge (m3/s)
L=Length of the cross section of weir (m)
H=Height of the weir (m)
3.33 and 0.22 are constants for the equation.
Since Length of river cross section is constant, it
implies that the discharge Q is proportional to height H, hence change in
discharge Q will vary proportionally to the change in height H.
From the
equation (rectangular weir equation) the prototype will be tested with water of
Q =1M3
and a constant length of 3.3m.
Q=3.33(L-0.2H)*H3/2
1=3.33(3.3-0.22H)*H3/2
Introducing logs
Log 1=log 10.989+3/2logH-log 0.66+5/2logH
0=1.04096+3/2logH-(-0.17653)+5/2logH
H=0.4962M
Therefore from the Francis equation we shall expect an increase in height
of the river of 496.166mm when 1m3 of water is added.
CHAPTER FOUR
Table 5: Work Schedule
Activities
|
Jan
|
Feb
|
March
|
April
|
May
|
Literature review
|
|||||
v Feasibility
study
v Design
specifications
v Embodiment
design
|
|||||
Detailed design
v Budgeting
v Sourcing
for materials
|
|||||
Design for manufacture
v Design
v Fabrication
v Test
v Validation
|
|||||
Project presentation
|
CHAPTER FIVE
5.0 PROJECT BUDGET
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28 Review
F.A. Nagler, 1931: American
Society of Civil
Engineers Transactions, v. 95, p.
834-840.
Nettleton, G.H., 1931, Discussion
of Effect of turbulence
on the registration of current
meters, by D.L. Yarnell
and F.A. Nagler, 1931: American
Society of Civil
Engineers Transactions, v. 95, p.
812-814.
Newell, F.H., 1899, Rating the
meters: U.S. Geological
Survey nineteenth annual report,
1897-98, Part IV
Hydrology: United States
Geological Survey, p. 27-
30.
Ott, Ludwig A., 1931, Discussion of
Effect of turbulence
on the registration of current
meters, by D.L. Yarnell
and F.A. Nagler, 1931: American
Society of Civil
Engineers Transactions, v. 95, p.
826-829.
Pelletier, P.M., 1988,
Uncertainties in the single
determination of river discharge
A literature
review: Canadian Journal of Civil
Engineering,
v. 15, no. 5, p. 834-850.
Pierce, C.H., 1941, Investigations
of methods and
equipment used in stream gaging,
Part 1
Performance of current meters in
shallow depth: U.S.
Geological Survey Water-Supply
Paper 868-A, 35 p.
Raffel, D.N., 1965, Discussion of
Spill way discharge
coefficients for Rock Island Dam,
by C.C. Lomax,
1965: Journal of the Hydraulics
Division
Proceedings of the American
Society of Civil
Engineers, v. 91, no. HY6, p.
214-217.
28 Review
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