ā¢ Water under pressure contains energy.
ā¢ Turbines convert the energy in water into rotating mechanical energy.
ā¢ Impulse turbines convert the kinetic energy of a jet of water to mechanical energy.
ā¢ Reaction turbines convert potential energy in pressurized water to mechanical energy.
Impulse Turbines
ā¢ Tolerate sand.
ā¢ Easy to fabricate.
ā¢ Efficient at wide a range of head and flow.
ā¢ Anozzle convertspressurised water into a high-speed jet of water.
āLowFlow
āMedium to High Head
ā¢Turgo
āMedium Flow
āMedium to High Head
ā¢ Crossflow
āHighFlow
āLow to Medium Head
Pelton Turbines
ā¢ Maximum jet diameter about 1/3 bucket width.
ā¢ More jets increase flow and are used at low head.
Pelton Turbine |
Multiple nozzles
- Four to six nozzles may be added before splash interference occurs.
- Power output is proportional to the number of nozzles.
Spear Valves
ā¢ Aspear valve changes the nozzle size without stopping the turbine.
ā¢ Expensive.
Deflectors
ā¢ Deflectors can be used to vary flow.
ā¢ Usually used for emergency stop without causing water hammer.
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