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Prof. Chih-Jen Sung Page 1 of 4 Rev. Spring 201

ME3264: LAB 5

Fluid Flow Measurement

Professor Chih-Jen Sung

Spring 201

OBJECTIVE

The purpose of this laboratory exercise is to gain working experience with the use of different

fluid flow measurement devices, and to understand the advantages and disadvantages of each.

These devices are described in sufficient detail in Chapter 8 of our textbook*.

PREPARATION

1. Review textbook materials* on rotameters, venture meters, and turbine meters.

2. Review materials on LabVIEW.

3. HHoommeewwoorrkk: Determine the water flowrate (both Qideal and Q) through the Venturi meter

shown below. Conditions at (1): p1=735 kPa and D=30 mm. Conditions at (2): p2=550

kPa and d=18 mm. Water density is 1000 kg/m3. Express flowrate in liters/min.

EQUIPMENT LIST AND DESCRIPTION

1. Volumetric Technique: The Hydraulic Bench provides a reservoir with sloping sides

connected to an external sight tube accurately calibrated in liters of water to indicate the

contents of this reservoir. To measure flow rate, the outlet in the base of the reservoir is

closed by the use of a drain plug column, and a stopwatch is used to measure the time

required for the water level to rise between chosen graduations. The outlet is then opened

to return the contents of the reservoir to the sump.

* B.R. Munson, D.F. Young, T.H. Okiishi, and W.W. Huebsch, Fundamentals of Fluid Mechanics, Sixth

Edition, Chapter 8.

Rev. Spring 2014Prof. Chih-Jen Sung Page 2 of 4

2. Rotameter: A rotameter consists of a graduated vertical tapered tube with the fluid flow

moving upward through the tube, past the float, as shown below. Its accuracy is ±3% of

full scale reading.

3. Venturi Meter: A venturi meter is a device in which the fluid flowing through a pipe is

led through a contraction section to a throat having a smaller cross-sectional area than the

pipe, resulting in a pressure variation along the meter, as shown below.

4. Turbine Meter: The turbine meter shown below is a device which is connected in series

with the pipe through which fluid is moving. An Omega FTB604B Turbine Meter is used

in this experiment, with a flow range of 1-30 liters per minute (lpm), a factory-provided

calibration constant (K factor) of 1200 pulses per liter, and an accuracy of ±3% of

reading.

Rev. Spring 2014Prof. Chih-Jen Sung Page 3 of 4

EXPERIMENTAL

1. Become familiar with the Hydraulic Bench and its usage. In particular, since the

volumetric technique built into the hydraulic bench will be used as the reference flow

data (calculated using stopwatch readings), it will be important to establish some measure

of repeatability and uncertainty associated with this approach. Among other items that

should be investigated include the starting and ending readings and procedures to obtain

them. Should a preferred procedure become apparent from these efforts, you should

consider possible explanations for this outcome.

2. You should obtain calibration data for each of the flow measuring devices listed

How will you apply a tolerance range to the venture meter and sight gage?

a. When setting up each device, make sure the valve closest to the pump being

calibrated (the downstream valve in the left figure below) is fully open, while the

upstream valve shown in the right figure below is fully closed.

b. Start the pump using the on/off switch.

c. When opening the upstream valve to allow water to flow through the device being

calibrated, open it slowly to protect against damage to the device – particularly the

turbine meter. Open the valve fully or adjust to whatever steady state flow rate you

want to report.

d. Keep all electronics away from areas that do or even could get wet.

e. Any bubbles in the tubing and device must be eliminated [wwhhyy??] – as can be

accomplished by running the flow at high rates for a period of time.

f. The turbine meter requires a 6-18V DC power supply, and output pulses in the form of

square waves. Power should be connected to the appropriate sockets on the connector

if they are not already. Output voltage to LabVIEW through a BNC cable to the DAQ

2110 block. Keep in mind you will need the frequency of the signal to calculate the

lpm.

g. For the turbine meter calibration, you will need the number of pulses per unit time –

frequency. Construct a simple equation in LabVIEW to give a visual numeric readout

of lpm in real time.

Upstream

Valve

Downstream

Valve

On/Off

Switch

OPEN CLOSED

Rev. Spring 2014Prof. Chih-Jen Sung Page 4 of 4

h. How does this computer-acquired data compare with observed data using the other

flow sensing equipment?

i. You should acquire enough calibration data sets for each device to insure reasonable

checks on repeatability and hysteresis, etc.

REQUIREMENTS

Include all results in your notebook. After the experiment, you will be asked to discuss the

following.

1. Your calibration equations should be presented in the most appropriate regression

analysis outcome. Included with the calibration coefficients should be an estimate of the

uncertainty for those coefficients.

2. Your considerations of these calibrations of the different types of devices should include

the comparison as to relative coefficient uncertainty, appropriateness of a linear

regression, relative time to acquire calibration data, relative appropriateness of using a

“universal” calibration for any one device (based upon limited efforts with different units

of each device), and some consideration of the relative uncertainty of the measurement of

general but unknown flowrate with each device (i.e., which would likely be most accurate,

some particular but peculiar behavior of the device at selected flowrates or ratio of

flowrates, etc.).

END