PELTON TURBINE

• A tangential flow impulse type water turbine invented by Lester Allan Pelton.
• Useful turbine for hydro-power if water source has relatively high hydraulic heads and low flow rates.
• Most efficient among other impulse turbines with efficiency about 90%.

The main parts of Pelton Turbine are:

a.NOZZLE AND FLOW REGULATING ARRANGEMENT:

b.RUNNER AND BUCKETS:

c.CASING:

d.BREAKING JET:

Points to remember for pelton turbine

• Wheel velocity, u=ᶲ√(2gH)
• Jet velocity at the inlet, Vi=Cv√(2gH)
• Mean diameter or pitch of the pelton turbine,

         where,

• ᶲ=speed ratio and it’s value varies from 0.43 to 0.48

         Where,Cv =co-efficient of velocity=0.98 or 0.99

• D=

            Jet ratio,

• m=

           Where, D=pitch dia. Of wheel

•  No. of buckets, Z=15+0.5m

           d=jet diameter
           Where, m=jet ratio

• No. of jets=

WORKING

The water impulse energy exerts torque on the bucket-wheel system, spinning the wheel.
Pelton turbine gains mechanical energy purely due to change in kinetic energy of jet of water.
It is so designed that wheel velocity is half the jet velocity to obtain max. power or max. efficiency.

APPLICATION

• Useful turbine for hydro-power , when available source has high hydraulic head and low flow rates.
• The smallest pelton turbine can be used to tap power from mountain streams for flow of few gallons per minute.
• Multi-ton pelton wheels used on vertical oil pad bearings

ADVANTAGES AND DISADVANTAGES OF PELTON TURBINE

ADVANTAGES

• Simple in construction and easy maintenance
• Can be prepared out of metal, plastic, ceramic materials
• Can strictly extract energy as of fast moving fluid
• To derive more power, multiple jet(2 to 6) pelton wheel may be used

DISADVANTAGES

• Preferred in hydro-power while available source has high hydraulic head and low flow rates.
• A lot of head loss occurs when the river discharge is low.
• Not suitable for low-pressure streams by a high flow rate.

Reference

• Wikipedia
• www.learnengineering.org
• www.4mechtech.blogspot.com
• www.theconstructor.org
• “Fluid mechanics and hydraulic machines”-by “R. K. Bansal” and others