FRANCIS TURBINE - CONSTANT HEAD
Objective
To conduct the performance test on Francis turbine under constant head and to plot the operating characteristics.
Apparatus used:
Francis Turbine Setup with Centrifugal Pump, Pressure Gauges, Spring Balance with Weights etc.
Description Francis turbine: is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts.
Cavitation: is a phenomenon which manifests itself in the pitting of the metallic surfaces of turbine parts because of the formation of cavities.
Start the pump by pressing the start button and select the head.
Open the inlet valve to keep the pressure constant.
Constant Head (H) =
Apply the weight on the pan and note the spring balance reading.
Radius of brake drum (R)= 0.15 m
Dead weight of the pan =
Spring balance reading =
Torque =
τ (N-m) = (W - S)×R×gInsert the tachometer to note the speed of the motor.
Speed of motor (N) =
Take the hook gauge reading to find the discharge.
Initial reading (water level till crest) =
Final reading =
Head of water (h) =
Actual discharge, Qact =
Qact (m3/sec) = 2⁄3×Cd× l × √(2g) × h(3⁄2)- Cd: Co-efficient of discharge: 0.6
- l: Length of the wire = 0.47m
Observation
Speed of motor (N) =
Torque (τ) =
Constant Head (H) =
Actual discharge, Qact =
Specific Weight of water = 9810N/m3
Result
Input power =
Input Power (W) = γ × Qact × HOutput power =
Output Power (W) = (2 × π × N × τ)⁄60Efficiency =
Efficiency (%) = Output Power⁄Input Power× 100Unit power =
Unit power (W) = Output Power⁄√(H3)Unit speed =
Unit speed (rpm) = N⁄√HUnit discharge =
Unit discharge (m3/sec) = Qact⁄√H
