Objectives:
1. To familiarize with the working principle of Pelton Wheel.
2. To determine the characteristics of Pelton Wheel.
3. To determine the optimum efficiency point.
Introduction:
The pelton wheel is a very efficient impulse turbine invented by Lester Allan Pelton. The water jet shot the turbine blade and the forces are divided into two symmetrical parts. Unlike other turbine blade Pelton's paddle geometry was designed so that when the rim runs at ½ the speed of the water jet, and therefore the water is leaves with little energy.
Apparatus:
Pelton wheel and stopwatch.
Figure 1. Pelton wheel machine
Procedures: 1.) The pelton wheel machine is fully set up already. 2.) Now turn on the main power supply and start the pump. 3.) The nozzle jet is preset at fully opened position. The water shot from the nozzle caused the wheel to rotate. 4.) The speed is first set at 1200 rpm and then the wheel is allowed to run for 3 minutes for the flow rate to stable. 5.) The belt is attached to the pulley at the back of the Pelton wheel. Ensure the belt is seated properly on the groove of the pulley. 6.) The load 1, load 2, speed of the rotarion, pressure and water collection time for 20 liters are recorded. 7.) The load is apply to the wheel by tighten the load nut and decrease the speed. 8.) The values are recorded for every 100 rpm decrement of speed of the wheel until 800 rpm.
Results:
* Load (N) = F1 – F2 * Average speed (rad/s) = Average speed (rpm) x 2 π/60 * Torque (N·m) = Load (N) x radius of wheel (0.026 m) * Input power (W) = Pressure (N/m2) x Flow rate (m3/s) * Output power (W) = Torque (N·m) x Average speed (rad/s) * Efficiency = (Output Power / Input Power) x 100%
Discussion:
1.
2. Based on the graph of output power against speed, the trend is as the speed increases, the output power decreases. The same trend followed for the graph of torque