1. Design of Components of Francis Turbine
P M V Subbarao
Professor
Mechanical Engineering Department
Detailing to Infuse Reaction….

2. Specific speed in rpm
P in hp & H in meters

4. Selection of Speed of A Turbo Machine
Zp : Number of pairs of poles of the generator

5. Design of Any Selected Francis Turbine Unit
Different capacities for each sub-group.
Design for Normal Head.
Assume an overall efficiency: 94 – 96%
Calculate the required flow rate.

6. General Layout of A Hydro Power Plant
Power Tunnel:
Diameter: 15000mm
Length= 746m
Slope= 1 in 120
Actual velocity: 5.563m/s

7. Power Tunnel
Channel Bed Slope

8. Penstock : Consider Velocity equal to Actual Site Velocity

9. Estimate net Head available at the inlet turbine casing
Pipe Material
Absolute Roughness, e
micron (unless noted)
drawn brass
1.5
drawn copper
commercial steel 45
wrought iron
asphalted cast iron
120
galvanized iron
150
cast iron
260
wood stave
0.2 to 0.9 mm
concrete
0.3 to 3 mm
riveted steel
0.9 to 9 mm
Estimate net Head available at the inlet turbine casing

10. Dimensions of Guide Vane Wheel
Group NO.
Unit Size MW
Degree of Reaction, %
Dpenstock m
Vpenstock
m/s
Head loss 1
135.9 35 2 40 3 45 4
203.9 5 6

11. Design of Spiral Casing
dpenstock
Rcasing Q
Risv
Inlet to Stay vanes

12. Runner
Guide vanes Ring
Stay vanes Ring

13. Design of the Guide Vanes How to choose the guide vane angle aegv at full load

15. Specifications of Guide Vanes
Slow Runner: Ns=60 to 120
Begv/Dmgv=0.033 – 0.04
Normal Runner: Ns = 120 – 180
Begv/Dmgv=0.125 to 0.25
Fast Runner: Ns = 180 to 300
Begv/Dmgv=0.25to 0.5
L: length of vane
L=15 to 30% of Degv

16. Dimensions of Guide Vane Wheel
Group NO.
Unit Size MW
Degree of Reaction, %
Digv, m
Degv, m
Bgv, m 1
135.9 35 2 40 3 45 4
203.9 5 6

17. Design of the Guide Vane Outlet Angle
The outlet angle can be calculated by assuming a vortex from the flow in the gap between the runner and the guide vanes
rigv
Begv
regv
Select appropriate value of n

20. Design of the Details of Stay Vanes
Theory of Relatively Whirling flow:
Bisv
rinlet Stay Vane
Besv
rexit stay Vane

26. At any angle q, the radius of casing is:
A full spiral is generally recommended for high head 300m, semi-spiral is recommended for low heat <50m.
In general k =1.0, however corrected using CFD.

27. Performance of Casing : Loss of Total Pressure
Rcasing
Risv
dpenstock Q
The losses in the spiral
casing as a sum f distributed losses and the exit losses

28. Friction losses
Friction losses in
the spiral casing
and stay vanes
Guide vane losses
Gap losses
Runner losses
Draft tube losses

29. Number of Guide/stay VanesNs
Z=8 10 12 14 16 18 20 24
<200
Dge,mm
<250
>1700
>200
<300
>2100

30. Validation of the Guide Vanes Design Degree Overlapping of the guide vanes
High Overlap
Low Overlap

31. Specifications of Guide Vanes
L: length of vane
L=15 to 30% of Degv

32. Minimum Number of Guide/stay VanesNs
Z=8 10 12 14 16 18 20 24
<200
Dge,mm
<250
>1700
>200
<300
>2100

33. The Runner

34. Velocity triangles rri rre Uri Vwi Vri Vfi Vai Ure Vwe Vre Vfe Vae bibe ae

35. Water particle
Water from spiral casing

36. Diameter of guide vane shaft Vs Runner Inlet Diameter
DRI
DRE
Dmgv

37. Design of the Runner Vanes How to choose the number of vanes
The number of guide vanes has to be different from the number of runner vanes.

38. Ub
Vwi
Vai
Vfi
Vri Ub
Vwi
Vai
Vfi
Vri
Vwi Ub
Vai
Vfi
Vri

39. Inlet Velocity Triangles Vs Ns
Low Specific Speed : Slow Francis Runner
Vwi
Vai
Vfi

40. Inlet Velocity Triangles Vs Ns
Low Specific Speed : Normal Francis Runner
Vwi
Vai
Vfi

41. Inlet Velocity Triangles Vs Ns
High Specific Speed : Fast Francis Runner
Vwi
Vai
Vfi

42. Specifications of Runner
Slow Runner: Ns=60 to 120
ai = 150 to 250
Kui = 0.62 to 0.68
bi = 900 to 1200
Bgv/Dmgv=0.04 – 0.033
Normal Runner: Ns = 120 – 180
ai = 250 to 32.50
Kui = 0.68 to 0.72
bi = 900
Bgv/Dmgv=0.125 to 0.25
Fast Runner: Ns = 180 to 300
ai = to 37.50
Kui = 0.72 to 0.76
bi = 600 to 900
Bgv/Dmgv=0.25to 0.5

43. Velocity triangles rri rre 13o < be < 22o Uri Vwi Vri Vfi Vai
Ure
Vwe
Vre
Vfe
Vae bi ai be ae
13o < be < 22o

44. Design for Maximum Power

45. Net Positive Suction Head, NPSH

46. NPSH required

47. Dimensions of the outlet
13o < be < 22o
1,05 < a < 1,15
0,05 < b < 0,15
Highest value for highest head

48. Remaining head to be used :
Extra head to be converted into kinetic energy:
Preferred Exit Velocity Triangle:
DRI
DRE
13o < bRE < 22o

49. Available Inlet velocity Triangle

50. Runner Design