1. Characteristic values
Reaction ratio R
Head coefficient y
Flow coefficient j

2. Reaction ratio for hydraulic machines
The reaction ratio can be defined as the pressure fraction of the total net specific energy which is converted to mechanical energy in the runner.

3. Reaction ratio for a Pelton turbine
Example for a Pelton turbine :
cu1 = 1,0
cu2 = 0
u1 = 0,5
cm1 = cm2
R = 0,0

4. Reaction ratio for a Francis turbine
Example for a Francis turbine:
cu1 = 0,72
cu2 = 0
u1 = 0,69
R = 0,52

5. Reference line Inlet Runner Outlet guide vanes Inlet guide vanes
Draft tube
Outlet
runner
Energy converted in the turbine
Reference line

6. Reaction ratio for a Kaplan turbine
Example for a Kaplan turbine:
cu1 = 0,6
cu2 = 0
u1 = 0,83
R = 0,64

7. Aksialturbin R=0 u1 w1 c1 u1 c1 w1 w u2 w2 c2

8. Aksialturbin R=0,5 u1 w1 c1 w u2 w2 c2

10. Reaction ratio
The reaction ratio can be defined as the ratio between the enthalpy difference over the runner and the total change of enthalpy. p3 p3 h h p2 3 p2
Guidevanes
Guidevanes p1 p1 1
Runner
Runner 2 2 1 s s

11. Head coefficient for hydraulic machines

12. Flow coefficient for hydraulic machines

13. TYPE R j y l u2 c2m a1 b2 Impulse turbine Reaction turbine
0,05
0,25
0,40
0,45
1,20 4 6
3,4
5,5
0,4
0,5
0,18
0,20
0,60 12 15 30 18 24 45
Reaction turbine
0,30 2 3
1,7
2,8
0,58
0,70
0,26
0,75 20
Radial turbine
1,0
0,50
1,50
0,35
1,00 -
Curtis turbine
0,15
0,90 16 13
0,10
0,22
Axial compressor
0,8
0,9
1,4
1,6
1,1 40 80 70
Source: Strømningsmaskiner, Bind 3, Jan M. Øverli