Flowmeter Calibration
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University of Illinois, Urbana Champaign *
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Course
335
Subject
Aerospace Engineering
Date
Apr 3, 2024
Type
docx
Pages
4
Uploaded by AdmiralHamster1144
Calibration of a Flow Meter Instructible
Krishna Ramasubramanian - ABH
pr16@illinois.edu
9/6/2022
Bill of Materials (BoM):
-
Pipe Flow Apparatus with Water Supply
-
Orifice plate -
Water holding tank for discharge
o
Balance beam o
Weight markers
o
Balance pan
o
Cursor
-
Stopwatch
-
Stool
-
Team Members
Step 1 - Background
This experiment aims to determine the flow coefficients as functions of the flow rate in terms of the Reynolds number of bulk-flow measuring instruments that rely on observations of pressure change, such as Venturi meters and orifice-plate meters.
Then, the experimentally discovered coefficients are contrasted with the remaining 2 devices. Furthermore, a paddlewheel flowmeter will be used downstream of the orifice plate measurement and the venturi effect measurement. There is also a manometer in conjunction with a piezometric differential measurement. In this process of calibration, we will utilize the results of the 3 means of flow measurements in order to calibrate the output signal for monitoring and control. Step 2 – Setup
The flow apparatus already is set in place inside the fluid mechanics lab. The differential manometer and
the transducer are required to be at specific flow rates based on differential pressures, and Q is proportional to pressure difference’s heights squared. Next, we also need to have a tank with a drain valve at the end of the valve discharge, a scale for the tank, and a timer.
There needs to be a person checking if the pressure differential in the manometer is the correct value based on the flow rate % we want. Then, another team member needs to open and close the valve based on the mass of water in the flow tank.
Step 3 - Measurement
Calibrating this flowmeter, there are 9 flow rates that we want to get as data points. Starting from the max flow rate, we take 9 different % values that are descending, 90% flow rate, 80%, and so on until 20%. Each of these flow rates correspond to the pressure differential at the start squared. We do this in 2 setups – one with the orifice plate, the other with the venturi effect flow meter.
At the discharge tank, we take the time the time it takes to fill the tank to 400 lbs after the discharge valve is closed.
Using these data points of the 2 different setups, cross verifying it with the amount of time it takes for the flow to fill up the tank, we correlate it with the different voltage values we get it from the paddle flow meter. The slope we get is the constant correlates with the flow that causes the flow meter to generate electricity.
Step 5 – Data Analysis
The data that was collected in group ABH is as follows:
0
10
20
30
40
50
60
70
80
90
0.000
0.005
0.010
0.015
0.020
0.025
0.030
f(x) = 0 x^0.48
R² = 0.99
f(x) = 0 x + 0.01
R² = 0.97
f(x) = 0.01 exp( 0.02 x )
R² = 0.81
Flow Rate
Manometer deflection [cm]
Flow rate, Q [m^3/s]
0
1
2
3
4
5
6
7
0.000
0.005
0.010
0.015
0.020
0.025
0.030
f(x) = 0 x − 0
Data Points
Paddlewheel voltage [V]
Flow rate, Q [m^3/s]
Flowmeter calibration, data shows the result for the flow rate and the paddlewheel voltage.
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The exponential curve does fit the form Q = K(dH)^m, as the manometer deflection follows a natural log progression. There is also a fit of 0.873, which is incredibly likely that this trend follows the power law relation. 0
100000
200000
300000
400000
500000
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
f(x) = 0.02 x^0.29
R² = 0.9
Reynold's Nymber
Cd Discharge Coefficient
This graph is the inverse of the data points I selected, and should produce an exponential decay function
if taken the inverse of. These are not constant to the reynold’s number being tested, and not they’re close to the actual values, as for the correlation for the beta being 0.4965 (0.5) (orifice plate). The range for the data starts near 0.6 for Cd, but starts much higher at near 0.86 for us. We would need to account
for greater inconsistency in the amount of energy being lost in the physical system, accounting for air and cavitation, and bends in the pipes to greater actualize values.
The paddlewheel flowmeter does, as there is a near perfect linear fit for all the data points we tested, therefore consistently showing the working of the flowmeter for data points we reference from Signet. There is no need to breakdown different flowrates into velocity, as there is already a consistent linear pattern emerging for the voltage.