# A Pelton wheel is to be designed for a pitch diameter of 1 m and jet diameter of 0.1 m. The number of buckets on the runner computed by Taygun’s formula is:

A Pelton wheel is to be designed for a pitch diameter of 1 m and jet diameter of 0.1 m. The number of buckets on the runner computed by Taygun's formula is:

#### SOLUTION

The Pelton turbine which was invented in 1889 is the most widely used tangential flow impulse turbine. It is extensively used for high head and low discharge installations. The water from the reservoir flows through the penstocks at the outlet of which a nozzle is fitted.

The number of buckets for a Pelton wheel should be such that the jet is always completely intercepted by the buckets so that the volumetic efficiency of the turbine is very close to unity. The number of buckets is usually more than 15. Certain empirical formulae have been developed for determining the number of buckets.

One such formula which is widely used has been given by Taygun according to which the number of buckets Z is approximately given by

Number of buckets required

$Z = \left( {\frac{D}{{2D}} + 15} \right)$

Where

D = Wheel Diameter or pitch diameter = 1
d = Jet diameter  = 0.1

$Z = \left( {\frac{1}{{2 \times 0.1}} + 15} \right) = 20$

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