Water-Turbine

• Water under pressure contains energy.
• Turbines convert the energy in water into rotating mechanical energy.
• Impulse turbines convert the kinetic energy of a jet of water to mechanical energy.
• Reaction turbines convert potential energy in pressurized water to mechanical energy.

Impulse Turbines

• Tolerate sand.
• Easy to fabricate.
• Efficient at wide a range of head and flow.
• Anozzle convertspressurised water into a high-speed jet of water.

•Pelton
–LowFlow
–Medium to High Head
•Turgo
–Medium Flow
–Medium to High Head
• Crossflow
–HighFlow
–Low to Medium Head

Pelton Turbines

 

 • At least one jet of water strike the buckets at atmospheric pressure.
• Maximum jet diameter about 1/3 bucket width.
• 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

• Aspear valve changes the nozzle size without stopping the turbine.
• Expensive.
                             

                                                                         Deflectors
• Deflectors can be used to vary flow.
• Usually used for emergency stop without causing water hammer.

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