Propeller Turbine vs Kaplan Turbine

8/18/2019 Propeller Turbine vs Kaplan Turbine

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Kaplan Turbine

P M V Subbarao

Professor

Mechanical Engineering Department

Pure Axial Flow with Aerofoil Theory…


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y

U b

V wi

V ai

V fiV ri

Vwi

U b

V ai

V fi

V ri

The Fast Machine for A Low Head


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Kaplan Turbine• The kaplan turbine is a great development of early !th century"

• #nvented by $rof" %iktor Kaplan of Austria during &'&( ) &'"• The Kaplan is of the propeller type* similar to an airplane propeller"

• The difference between the $ropeller and Kaplan turbines is that the$ropeller turbine has fi+ed runner blades while the Kaplan turbinehas ad,ustable runner blades"

• #t is a pure a+ial flow turbine uses basic aerofoil theory"• The kaplan-s blades are ad,ustable for pitch and will handle a great

variation of flow very efficiently"

• They are '!. or better in efficiency and are used in place some ofthe old /but great0 Francis types in a good many of installations"

• They are very e+pensive"

• The kaplan turbine* unlike all other turbines* the runner-s blades aremovable"

• The application of Kaplan turbines are from a head of m to 1!m"


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Francis to Kaplan


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Ma,or Kaplan $lants in Karnataka* #ndia

S.No. Station No. Units× unit Size,

MW

DesignHead

Speedrpm

DesignDischarge,

Cumecs

& L$H 2 3"4 '"4 !! &!&

Kadra 3 2 5 ("! &1"56 &34"4

( Kodasalli ( 2 1! (3"! &66"63 &(

1" Almatti & 2 &44 2 44

1"!' &53"4! 6"6'&&4"1


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7pecific 7peed of Kaplan Turbine

• 8sing statistical studies of schemes* F" 7chweiger and 9" :regoryestablished the following correlation between the specific speed

and the net head for Kaplan turbines;

156"!53"('

H N s =

14

H

P N N s =

P in watts"


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The 7chematic of Kaplan Turbine


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Ma,or $arts of A Kaplan Turbine


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7uperior Hydrodynamic Features

7ection of :uide ssential for High >fficiency at low Heads


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?lassification of Kaplan Turbines

• The Kaplan turbine can be divided in double and singleregulated turbines"

• A Kaplan turbine with ad,ustable runner blades and

ad,ustable guide vanes is double regulated while one withonly ad,ustable runner blades is single regulated"

• The advantage of the double regulated turbines is that theycan be used in a wider field"

• The double regulated Kaplan turbines can work between&4. and &!!. of the ma+imum design discharge@

• the single regulated turbines can only work between (!.and &!!. of the ma+imum design discharge"


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Hydraulic >nergy iagram

H s

H total H ri H re

H m


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C!"#$!$#%N

• ?avitation occurs especially at spots where the pressure is low"• #n the case of a Kaplan turbine* the inlet of the runner is Buite

susceptible to it"

• At parts with a high water flow velocity cavitation might alsoarise"

• The ma,or design criteria for blades is ; Avoid ?avitation"

• First it decreases the efficiency and causes crackling noises"

• The main problem is the wear or rather the damage of theturbineCs parts such as the blades"

• ?avitation does not ,ust destroy the parts* chemical properties arealso lost"


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The suction head

• The suction head H s is the head where the turbine is installed@

• if the suction head is positive* the mean line of turbine is located abovethe trail water@

• if it is negative* the mean line of turbine is located under the trail water"

• To avoid cavitation* the range of the suction head is limited"

• The ma+imum allowed suction head can be calculated using thefollowing eBuation;

net

devapatm

s

H g

V

g

p p H σ

ρ −+

−=

net

de s

gH

V N

41&"&

16"&+×=σ


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esign of :uide


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Eutlines of Kaplan =unner


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esign of Kaplan =unner

Drunner

D%ub


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The Kaplan =unner


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Adaptation Mechanism inside the Hub


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#nside the Hub


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$arts of =unner


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Hu& diameter

• The hub diameter Di can be calculated with the following eBuation;

+=

srunner

%ub

N D

D !'4&"!4"!


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'unner diameter section

The runner diameter can be calculated by the followingeBuation;

( ) N H N D srunner ×××+×= 6!

6!"&3'"!4"51

1(

H

& N

N s =


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:eneric esigns for Micro Hydel $lants


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Hydrodynamics of Kaplan lade


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D(S#)N %* $H( +!D(

Two different views of a blade

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Propeller Turbine vs Kaplan Turbine