Title: Determination of Force on Turning Vanes.
Purpose:
1. The student shall understand how the "impact" force is affected by using different shaped vanes.
Objectives:
1. Determine the variation of "impact" force, FJ , with mass flow rate for different shaped vanes.
2. Place all results in tabulated form.
3. Plot (ordinate) versus m. (abscissa) on 2 x 2 log-log paper and determine and c from the averaging line of each vane as described in the theory section.
4. Test the and c values in FJ = Km.c for one point on each vane.
5. Discuss the similarities or differences in curves and the values of and c for each vane.
Experimental Procedure:
1. Attach one of the vanes to the weight beam.
2. Prior to turning on the water and with the maximum sliding weight in zero position, balance the beam by adjusting the tension of a spring situated above the beam.
3. After the water is turned on to maximum flow rate, balance the beam again by moving the weight. If this puts the weight beyond the end of beam, place it at the end and reduce flow to balance.
4. Record the sliding weight, 5.89 N and its position on the scale.
5. Find the water flow rate with the weight tank situated underneath the apparatus. Once the experiment is in a steady state condition (moment arm balanced) move the tank lever to the FILL position. Then when the fulcrum weight lever moves upward, start the timer and place the selected weight plate on the fulcrum. Once the fulcrum weight lever moves upward again STOP the timer, and move the tank lever to the drain position.
6. Move the moment arm weight toward 0 approximately one 10th of the initial distance to obtain approximately eight to ten readings.
7. Rebalance the beam by adjusting the flow.
8. Record the position on scale and the number of seconds to weigh a fixed amount of water.
9. Replace vanes and repeat steps 1-8.
Results:
1. Place the following items in tabulated form:
a) Weighing tank mass, 15 Kg, or 30 lb, depending on weighing unit.
b) Time (seconds)
c) Beam weight (Newton's): convert mass to weight
d) Beam weight position (mm)
e) Mass flow rate m. (Calculated) (Kg/S)
f) Force of the Jet FJ (Calculated) (N)
2. Plot FJ (ordinate) versus (abscissa) on 2 x 2 log-log paper and determine and c from the best fit straight line of each vane as described in the theory section. Put both on the same graph. (Hint: Use the upper six or eight valves to form the line. Lower valves will introduce some error since the nozzle is located about 10 mm below the vane to allow for water escape to the weighing tank.)
3. Test the and c values in FJ = Km.c for one point on each vane and compare to tabled values.
4. Discuss the similarities or differences in curves and the values of and c for each vane.
5. Discuss all sources of possible errors.