LAB 3 Powerhouse Design

 

Jet Impact
Switch Assembly
Pelton Wheel

Introduction

Safety Considerations

  • Closed toed shoes are required in the Hydrotechnical Lab
  • Safety glasses are required in the Hydrotechnical Lab
  • Friction wheel may get hot
  • The hoist is to be used by the TA for moving the Pelton wheel assembly

Link to Lab 3 Manual CIVL315_Lab 3_ Manual_Aug2018_Final

Procedure

Jet Impact

The following video will demonstrate the important procedures when measuring jet impact.

Powerhouse Design

Powerhouse Design

    1. The first task is to calibrate the needle valve. Check that the reservoir is sufficiently full and clean. Very dirty water can damage the pressure gauge.
    2. Check that the pump output valve is closed and turn on the pump.
Pump Output Valve

Pump Output Valve

    1. Open the pump output valve completely.
    2. Open the needle valve one turn.
Needle Valve

Needle Valve

  1. Record the pressure just before the needle valve.
  2. Utilize the upper compartment to measure flow rate.The measuring instrument along the side of the tank is already calibrated in ft3.
    flow_rate
  3. Open the upper drainage valve after the measurement to avoid overflow.
  4. Lower the pitot tube into the stream to measure the velocity of the jet. It can be difficult to properly align the tube. The higher the water level in the buffer tank, the better the alignment. 
If there is air in the tube leading up to the pressure gauge the reading 
will be inaccurate. The reading from the pitot tube should almost match the pressure 
reading before the needle valve.
  5. Remove the pitot tube from the jet.
  6. Close the needle valve.
  7. The Load cell readout needs to be set up for measuring impact.  Select “Measure” then “Impact”. To verify the readout is operational, place the calibration weight on the arm opposite the load cell and verify that you should be measuring approximately  5 lbs (depends where on arm the weight is placed). Remove calibration weight
  8. Check that the alignment indicators line up on the force plate bearings. If the Load cell readout does not show zero load select “Exit” -> “Setup” -> “Zero” -> “Impact”  then repeat step 7.
  9. Open the needle valve one turn and note the load being measured.
  10. Record the force on the load cell due to the jet.
  11. Continue opening the valve one turn and recording the force until you have data for 1, 2, 3, 4 and 5 full turns of the needle
valve.
  12. Close the needle valve.
  13. Close the pump output valve.
  14. Turn off the pump.


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Switch Assembly

The following video shows the steps needed to properly switch the assembly to Pelton Wheel.

    1. Ask the TA to assist you.
    2. Unscrew the six nuts attaching the jet impact apparatus (using the attached wrench) to the reservoir assembly. Using the crane, the TA will lift the Pelton wheel off the cabinet and swing it back out of the way.   The jet assembly can then be lifted off by hand ( by two people) and placed on the cabinet stand where the Pelton wheel was sitting previously.
    3. Have the TA assist you in swinging the Pelton wheel assembly into place (friction wheel should be facing operators) and then the TA will lower the Pelton wheel onto the bolts (ensure cups are pointed towards jet).  Do not get underneath the Pelton wheel assembly when it is being moved.
    4. Attach and secure the six bolts with the wrench attached to assembly.
Pelton Wheel

Pelton Wheel (with cups) and friction wheel (with belt)


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Pelton Wheel

The following video shows the steps needed to obtain measurements from the Pelton wheel.

  1. On the Load cell output select “Measure” then “Torque”.  If the output is not  showing zero then zero the reading by selecting Exit -> Setup ->Yes -> Torque  then back to the measurement mode ( Measure -> Torque). Pull down on the rope to verify the load readout is working.
  2. Turn on the pump.
  3. Open the pump outlet valve fully. Pressure at the needle valve should be approximately 30 PSI.
  4. Open the needle valve one turn. The splashes should be perpendicular to the direction of travel to achieve maximum inertia transfer. You want to maximize the power output by varying rpm.
  5. With no weight attached to the rope record the wheel RPM with the tachometer. Point the tachometer at the reflective sticker on the friction wheel. Repeat this measurement several times to check accuracy.
  6. Add weight to the rope until the wheel stalls (add in 0.5 Kg increments, the stalling weight should be around 3Kg). Record the weight and the load with the wheel stalled.
  7. Remove 0.5 kg from the rope and wait a few seconds for the speed to stabilize.
  8. Record the weight on the rope, the load cell reading and the rpm (using tachometer).
  9. Repeat steps 12-13 until no weight is left on the rope.
  10. Close the needle valve and then close the pump outlet valve.
  11. Turn off the pump.
  12. Measure the radius of the friction wheel and Pelton wheel.

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