Dr.Abdul Qadeer Khan

The Pelton wheel is a water impulse turbine. It was invented by Lester Allan Pelton in the 1870s. The Pelton wheel extracts energy from the impulse of moving water, as opposed to its weight like traditional overshot water wheel. Although many variations of impulse turbines existed prior to Pelton 's design, they were less efficient than Pelton 's design; the water leaving these wheels typically still had high speed, and carried away much of the energy. Pelton 's paddle geometry was designed so that when the rim runs at ½ the speed of the water jet, the water leaves the wheel with very little speed, extracting almost all of its energy, and allowing for a very efficient turbine. Contents [hide] * 1 Function * 2 Applications * 3 Design rules * 4 Turbine physics and derivation * 4.1 Energy and initial jet velocity * 4.2 Final jet velocity * 4.3 Optimal wheel speed * 4.4 Torque * 4.5 Power * 4.6 Efficiency * 5 System components * 6 See also * 7 References * 8 External links |
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[edit]Function
The water flows along the tangent to the path of the runner. Nozzles direct forceful streams of water against a series of spoon-shaped buckets mounted around the edge of a wheel. As water flows into the bucket, the direction of the water velocity changes to follow the contour of the bucket. When the water-jet contacts the bucket, the water exerts pressure on the bucket and the water is decelerated as it does a "u-turn" and flows out the other side of the bucket at low velocity. In the process, the water 's momentum is transferred to the turbine. This "impulse" does work on the turbine. For maximum power and efficiency, the turbine system is designed such that the water-jet velocity is twice the velocity of the bucket. A very small percentage of the water 's original kinetic energy will still remain in the water; however, this allows the bucket to be emptied at the same rate it is

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