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Pelton Wheel Turbine

P M V SubbaraoProfessor

Mechanical Engineering Department

Best Means to Recover Energy form High Energy Intensity Fluids….

Pelton Turbine: The First Titled Impulse Turbine

• Lester Allan Pelton, considered to be the father of modern day hydroelectric power, was born in Vermilion Township, Erie County, in Ohio.

• On September 5, 1829.

• Pelton embarked on an adventure in search of gold.

• Shifted to California from Ohio in 1850, he was 21 years old.

• After a failed quest for gold, he joined in the gold mines as a millwright, and carpenter at Camptonville, Yuba County, California in 1864 . 

Captonville

Camptonville Gold Mine : Use of Hydro Power

• Water wheels were being used to provide mechanical power for all things mining, air compressors, pumps, stamp mills and operating other machines. 

• The energy to drive these wheels was supplied by powerful jets of water which struck the base of the wheel with flat-faced vanes. 

•  These vanes eventually evolved into hemispherical cups, with the jet striking at the center of the cup on the wheel. 

• Pelton observed that one of the water wheels appeared to be rotating faster than other similar machines.

• It turned out initially that this was due to the wheel had come loose, and moved a little on its axle. 

Damaged Wheel is A Better Design

• He noticed the jet was striking the inside edge of the cups, and exiting the other side of the cup. 

• His quest for improvement resulted in an innovation.  

• Pelton reconstructed the wheel, with the cups off center only to find again that it rotated more rapidly. 

• Pelton also found that using split cups enhanced the effect. By 1879 he had tested a prototype at the University of California, which was successful.

• He was granted his first patent in 1880.

• By 1890, Pelton turbines were in operation, developing thousands of horsepower, powering all kinds of equipment.

A Patent on Water Wheel

• In 1889 Pelton was granted a patent with the following text. 

• "Pelton water turbine or wheel is a rotor driven by the impulse of a jet of water upon curved buckets fixed to its periphery; each bucket is divided in half by a splitter edge that divides the water into two streams. The buckets have a two-curved section which completely reverses the direction of the water jet striking them."

Special Design Features to Minimize Irreversibilities…..

Hydro Electric Plant with High Heads

gHpV

pp atmpenstock

staticfriction

2

2

frictionjet ghgH

V

2

2

Nozzle

H

patm

HEPP with Pelton Wheel

Different Layouts of Pelton Turbine

• Arrangement of Jets

• Arrangement of Runners

• Arrangements of Turbine Shaft

Arrangement of Jets

Arrangement of Runners

Parts of Advanced Pelton Turbine

• The main components of a Pelton turbine are:• (i) water distributor and casing, • (ii) nozzle and deflector with their operating mechanism, • (iii) runner with buckets, • (iv) shaft with bearing, • (v) auxiliary nozzle. • Auxiliary nozzle is used as brake for reducing the speed

during shut down. • The runner is located above maximum tail water to permit

operation at atmospheric pressure.

Key Parts of Pelton Turbine

Runner with Buckets• The runner consists of a circular disc with a number (usually more

than 15) of buckets evenly spaced around its periphery.

• Each bucket is divided vertically into two parts by a splitter that has a sharp edge at the centre and the buckets look like a double hemispherical cup.

• The striking jet of water is divided into two parts by the splitter.

• A notch made near the edge of the outer rim of each bucket is carefully sharpened to ensure a loss-free entry of the jet into the buckets,

• i.e., the path of the jet is not obstructed by the incoming buckets.

Bucket Displacement Diagram

Design of Nozzle is of Prime importance in Pelton Wheel

Nozzle used in 62.5 MW Pelton Wheel

Mechanism of Control of Jet dimensions

The Nozzle and Jet : A Key Step in Design

d0djet,VC

Velocity of the jet at VC:

gHV idealVCjet 2:,

gHKV vactualVCjet 21:, 99.098.0 1 vK

Jet carrying a discharge of Q to deliver a power P

gHKdQ vVCjet 24 1

2,

To generate a discharge of Q, we need a least jet diameter of

gHK

Qd

v

VCjet2

4

1

,

QgHP turbine

Diameter of the Jet at the outlet, do

gHKdQ voo 24

2

83.081.0 vOK

It is important to find out the VC and outlet jet diameters/areas