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Classification of Hydraulic Turbines

P M V Subbarao

Professor

Mechanical Engineering Department

Why So Many Variations ?????  A Committed Engineering to Match A Machine to 

the Resource….. 

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Pelton Wheel Turbine : The Lowest Specific Speed Machine

Pure and maximum change in direction of flow velocity…. 

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Modern Pelton Wheel

Original Pelton Wheel

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Vri = Vai - Ub 

Vre = -Vri 

Ub 

Vae = Vre +Ub 

Vai 

Analysis of Simple Moving Impulse Blade

baibbaibriae U V U U V U V V  2

bairire U V V V V  2

bai R

bai A

U V mV mF 

U V mV mF 

2

2

bbaib

bb Rb

U U V mP

V U mU F P

2

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Kinetic power lost by the jet :

bbai

bai

bai

U U V mKP

U V V m

KP

U V V m

V V m

KP

ai

aiaeai

2

22

222

22

2222

Power lost by jet = Power gained by the Blade

bb jet  jet  jet bbaib U U V V  AU U V mP

  22

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PowerJet

PowerBladeBladeImpulse of  Efficiency

gH 

U U gH blade

22 

gH 

 DN  DN gH 

blade

606022

  

 

 

  

 

2

60

2

max..max

gH  ND

gH U  eff 

 

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be 

Does Incoming Jet Velocity Effect the Newton’s Angle of 

Deflection?

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Turgo Turbine

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Cross-flow Turbine

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Variations of Cross-Flow Turbines

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Specific Speed

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Analysis of Simple Stationary Reaction Blade

Vai  Vri  Vre Vae U

U V V  airi U V V  reae

Change in velocity : rire V V V 

rire R

rire A

V V mF 

V V mV mF 

Motive Power Generated: U V V mF U P rire Rblade

U U V V mP aiaeblade 2

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Power of incoming jet :

2

2

,ai

iin jet 

V hmP

Power of outgoing jet :

2

2

,ae

eout  jet 

V hmP

22

22ai

eiae V 

hhV 

2

2 aieiae V hhV 

U U V V hhmP aiaieiblade 222

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For an incompressible fluid 

U U V V  H  H gmP aiaieiblade 222

U U V V gH mP aiaiblade 222

gH 

U U V V gH  aiai

bladereaction

222

,

 

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Bulb Turbine

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Tubular Turbine

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Kaplan Turbine

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Vai 

Vae 

Vri 

Vre

 

Simple Impulse-Reaction Blade

Jet will lose power both by Impulse and Reaction.

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Propeller Blade Turbine

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Francis Turbine

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Specific Speed

   H  e  a   d ,  m

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Turbine Specific Speed (rpm)

Pelton 10 – 30

Turgo 20 – 70

Crossflow 20 – 200

Francis 30 – 400Propeller and Kaplan 200 - 1000

Generally, the turbine manufacturer specifies thespecific speed of its turbine.

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MORE ADAPTED TYPE OF TURBINE AS FUNCTION OF THE   SPECIFIC SPEED. Specific Speed in r.p.m.  Turbine type   Jump height in m  

Until 18 Pelton of an injector 800

From 18 to 25 Pelton of an injector 800 to 400

From 26 to 35 Pelton of an injector 400 to 100

From 26 to 35 Pelton of two injectors 800 to 400

From 36 to 50 Pelton of two injectors 400 to 100

From 51 to 72 Pelton of four injectors 400 to 100From 55 to 70 Very slow Francis 400 to 200

From 70 to 120 Slow Francis 200 to 100

From 120 to 200 Normal Francis 100 to 50

From 200 to 300 Quick Francis 50 to 25

From 300 to 450 Extra-quick Francis 25 to 15

From 400 to 500 Extra-quick helix 15

From 270 to 500 Slow Kaplan 50 to 15

From 500 to 800 Quick Kaplan 15 to 5

From 800 to 1100 Extra-quick Kaplan Less than 5

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Correlations for Specific Speed

• Several studies on a large number of hydro projects haveestablish the following correlation of specific speed andnet head .

• Crossflow N s=513.25/H 0.505

 

• Propeller N s=2702/H 0.5 

• Kaplan N s=2283/H 0.486 

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How many Varieties of Resources Available in India ?

There is A Great Need to Generate

Innumerable Number of Creative Ideas for Moving

Towards A Developed Nation…..