Kaplan turbine

Jebba, Nigeria

*Q = 376 m3/s

*H = 27,6 m

*P = 96 MW

D0 = 8,5 m

De = 7,1 m

Di = 3,1 m

B0 = 2,8 m

Machicura, CHILE

*Q = 144 m3/s

*H = 36,7 m

*P = 48 MW

D0 = 7,2 m

De = 4,2 m

Di = 1,9 m

B0 = 1,3 m

Outlet

draft tube

Outlet

runner

Inlet

runner

Outlet

guide vane Inlet

guide vane

Flow rate Q

Runner blade angle

f = constant

Hydraulic efficiency

Hill chart

c1

v1

u1

c2 v2

u2

Hg

cucu 2u21u1h

Pressure distribution and

torque

Lift

Drag

Torque

Arm

L

D

c

LChord

4

a

FLift

FDrag

v

AVCF

AVCF

DD

LL

2

2

2

1

2

1

Blade profile data

L

D

C

C

Angle of attack

Angle of attack

Average relative

velocity

d

v

Pressure distribution and

torque

Pressure side

Suction side

Cord length, l 0,24 · l

Single profile

Cascade

The pressure at the outlet is lower for a cascade than

for a single profile. The cavitation performance will

therefore be reduced in a cascade.

Radial distribution of the

blade profile

CL =Lift coefficient for a cascade

CL1 =Lift coefficient for a single profile

The ratio t/l influences the lift coefficient in a

cascade. The cord length for a blade will therefore

increase when the radius becomes increase

Radial distribution of the

blade profile

Flow in the axial plane

The figure shows blades with two different design of

the blade in radial direction. This is because it will

influence the secondary flow in the radial direction

Main dimension of a

Kaplan turbine

n

o Q

1.5

Cml =0.12 + 0.18 0

Cm

l

2.0

0

0

0.5

(tilnærmet)

1.0

2.5 3.0

m1

n

m1

22

n

c

4QD

c4

dDQ

Diameter of the runner

Height of the guide vanes

and runner diameter

0.4

0.3

300 400

ns

B /D0

d/D

d/D

, B

/D0

500 700600 800 900

0.5

0.6

0.7

45

n

sH

Pnn

Gap between hub and ring

and the runner blades

Gap between the

blade and hub

Gap between the

blade and ring

Spalteåpning x =1000s/D

Vir

kn

ingsg

rad

0

0.80

0.85

0.90

1

s = x 10 d-3

2 3 4 5 6

Eff

icie

ncy

Gap

Runaway speed

kavitasjonskoeffisient

Rusn

ingst

all/

norm

alt

urt

all

Voit h

Cavitation coefficient

Runaw

ay s

pee

d

H

H10 S

The figure shows different runaway speed at

different runner blade openings. The runaway speed

is dependent of the cavitation as shown in the figure

Hill chart

Example

• Find the dimensions D, d and Bo

• Given data:

93,178,674,0Qn

o

sm7,171682,92Hg2

srad1,13

60

2125

60

2n

1m74,0

sm7,17

srad1,13

Hg2

2

3

nm78,6

sm7,17

sm120

Hg2

QQ

Speed number:

Diameter, D:

467,018,012,01 o

mc

mc

QD

m

n 3,4467,0

478,64

1

Diameter, d:

59016

22826125

4545

m

Hprpm

H

Pnn

n

s

0.4

0.3

300 400

ns

B /D0

d/D

d/D

, B

/D0

500 700600 800 900

0.5

0.6

0.7

m9,145,0Dd45,0D

d

Height, B:

0.4

0.3

300 400

ns

B /D0

d/D

d/D

, B

/D0

500 700600 800 900

0.5

0.6

0.7

m76,141,0DB41,0D

BO

O

Number of vanes, z:

95,0t

l

5z

Num

ber

of

bla

des

z