Examples Losses in Francis turbines NPSH Main dimensions

Francis turbines

X blade runnerTraditional runner

SVARTISEN

P = 350 MWH = 543 mQ* = 71,5 m3/SD0 = 4,86 mD1 = 4,31mD2 = 2,35 mB0 = 0,28 mn = 333 rpm

P = 169 MWH = 72 mQ = 265 m3/sD0 = 6,68 mD1e = 5,71mD1i = 2,35 mB0 = 1,4 mn = 112,5 rpm

La Grande, Canada

Outletdraft tube

Outletrunner

Inletrunner

Outletguide vane

Inletguide vane

Hydraulic efficiency

n

uuh Hg

ucuc

= 2211

++

++

++

++

=3

23

31

21

1

3

23

31

21

1

z2chgz

2chg

lossesz2chgz

2chg

1

Losses in Francis Turbines

Draft tube

Output Energy

Head [m]

H

y

d

r

a

u

l

i

c

E

f

f

i

c

i

e

n

c

y

[

%

]

Losses in Francis TurbinesH

y

d

r

a

u

l

i

c

E

f

f

i

c

i

e

n

c

y

[

%

]

Output Energy

Output [%]

Friction losses between runner and covers

Friction losses

Gap losses

Gap losses

Gap losses

Friction losses in the spiral casingand stay vanes

Guide vane losses

Friction losses

Runner losses

Draft tube losses

Relative path

Absolute path with the runner installed

Absolute path withoutthe runner installed

Velocity triangles

Net Positive Suction Head, NPSH

1

gcz

gchhz

gch b ++++=++ 222

23

3

23

32

22

2'22 hhh b +=

23

23

3 2zz

gc

hHs ++=

g2czHhz

g2ch

23

2sb2

22

2 ++=++

JJHh

g2ch sb

22

2 +=+

NPSH

vasb hJgcHhh >

= 2

22

2

NPSHs2b HhhNPSH =

NB:HS has a negative value in this figure.

AsvabR NPSHHhhNPSH =