To perform the experiment on Pelton wheel

To perform the experiment on Pelton wheel, plot its characteristics curves and determination of its efficiency.

Objective

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• To determine the efficiency of Pelton Turbine and plot its characteristics curves.

Apparatus

1. Pelton Wheel
2. Weights
3. Discharge measuring tank
4. Tachometer
5. Stop Watch

Theory

Braking Torque:-
Product of lever arm length and weight or load is called braking power
T = Fx L
Where
T = Braking torque
F = High reading-Low reading (on spring balance)
L = lever arm or radius of drum
Brake Horse power:-
It is the output power available at the shaft of Pelton wheel and is measured by applying brakes to the rotating braking drum.

Po = the output power or brake power
N = rpm of the shaft at braked position
T = Braking torque
1 H.P = 746 watts
= rate of performing 550ft-lbs of work per second
Indicated Horse Power:-
It is the input power supplied to the Pelton wheel in hydraulic form
Pin = I.H.P = ?QH
? = specific weight of water
Q = Discharge through the nozzle
H = Head available at the base of nozzle
Efficiency:-
It is the %age ratio b/w the output power available at the shaft of Pelton wheel (B.H.P) and input power supplied to it (I.H.P)

Gate Opening:-
It is the opening of the nozzle mouth in %age. Suppose if 6 turns are required in anticlockwise direction for 100% opening then 3 turns are required for 50% gate opening.
This experiment is being performed on two gate openings that are 100% and 50%.
Characteristic Curves:-
It is the graphical representation of the response of pelton wheel at varying speed efficiency, output power and braking torque.
Characteristics curves are required to study the behavior of the machine under varying speed and to determine the important parameters of the machine like, maximum efficiency of the machine, normal speed, maximum braking torque, maximum power and maximum speed of the turbine etc.