Updated 8/9/06
Orifice and Free Jet Flow Experiment
For this experiment, you will need the Orifice and Free Jet Flow module and graph paper.
Figure 1: Orifice and Free Jet Flow Module
Figure 2: Orifice and Jet Apparatus
Procedure
1. Obtain the Orifice and Free Jet Flow module from the 2B60 module storage bay.
2. Place the Orifice and Free Jet module on one of the Hydraulics benches found on the 2B
level of the ITL near the door of the Machining Studio with the head tank on your left
side.
3. Ensure that the green hose on the left is tightly secured to the head tank and drains into
the bench.
4. Connect the inlet quick release connector (the hose attached to the base of the head
tank) to the inlet in the bench basin by pushing down on the ring, inserting the hose,
and releasing the ring. Be sure the connection has locked and the ball bearings are not
visible (it may take some force to ensure the connection is secure).
5. Secure the smallest orifice plate with O-rings to the head tank using the thumb screws.
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Updated 8/9/06
Figure 3: Thumb Screw and Orifice Plate
6. Take two pieces of graph paper and tape them together so that they are at least 17”
long. Place them on the backboard and secure it in place with the clip. Raise the
needles to clear a path for a water jet by adjusting the thumb screws.
7. Make sure the rubber stop between the overflow tank and the head tank is removed
and set aside (do not lose it!).
8. Verify that the main control flow valve is completely shut (Turned all the way clockwise)
9. Turn the motor switch ON. Confirm pump operation by listening to the motor.
Motor Switch
Main Control Valve
Figure 4: Motor Switch & Main Control Valve
10. Slowly open the main control flow valve on the Hydraulics Bench. The head tank
should fill with water.
11. Once the level in the head tank reaches the overflow pipe, adjust the main
control flow valve until the level in the head tank stays constant.
12. Record the head height using the scale on the side of the head tank.
13. Ensure that the water jet being emitted from the orifice coincides with the row
of measuring needles. If not, level the apparatus using the adjustable feet and
the level at the base of the head tank.
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14. Take note of the Vena Contracta (the most reduced diameter of the jet stream).
Is the cross sectional area of the jet of water coming out of the orifice the same
as the area of the orifice? Estimate whether or not the coefficient of contraction
Cc is close to unity.
15. Adjust each of the needles in turn to determine the jet path, marking the
position of the tops of the needles on the sheet of paper on the backboard. The
vertical difference between the top of the needle that lines up with the orifice
and the top of the needle that you are experimentally measuring is your y value.
Your x value is simply the horizontal distance between the orifice and each
needle.
16. Repeat for 3 more different head heights. Replace the rubber stopper and
carefully adjust the flow so the water level in the head tank is steady for each of
your different head heights. BE CAREFUL NOT TO OVERFLOW THE HEAD TANK.
Record the head level using the scale on the side of the head tank.
17. Repeat for the other orifice plates.
18. At the end of your experiment, turn the main control flow valve of the Hydraulics
Bench OFF.
19. Turn OFF the pump motor.
20. Carefully disconnect the inlet quick release connector to the Orifice and Jet
Apparatus and empty the water from the tube and the head tank into the bench.
21. Clean up any water that may have spilled onto the floor or on the bench.
22. Return the module.
*Note for Instructors: Procedure and theory to determine the coefficient of discharge
and coefficient of contraction can be found in Emptying of a Tank by an Orifice.
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