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Design & Analysis of Pelton Wheel Turbine

Design & Analysis of Pelton Wheel Turbine. P M V Subbarao Professor Mechanical Engineering Department. Internal Details of the Machine…. Koyna Hydro Electric Project. Koyna Dam from the catchment area of about 891.78 Sq. Km.

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Design & Analysis of Pelton Wheel Turbine

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  1. Design & Analysis of Pelton Wheel Turbine P M V Subbarao Professor Mechanical Engineering Department Internal Details of the Machine….

  2. Koyna Hydro Electric Project Koyna Dam from the catchment area of about 891.78 Sq. Km • Koyna river rises in the Mahabaleshwar, a famous hill station in the hill range of Sahyadri. • It flows in a north - south direction almost parallel to the Arabian Sea coast for a distance of 65 Kms.

  3. Details of Koyna Hydro Electric Project • Number of units: 4 • Capacity of each unit=250MW • Head • Normal Head=415m • Maximum Head=510m

  4. Creation of Reservoir

  5. Specific speed in rpm

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

  7. Questions to be Answered • Is it possible to change number of units in Stage IV? • What is the allowable speed of the generator for each unit, if number of units is 2, 5, 6 or 7?

  8. Design of Any Selected Pelton Wheel Unit • Different capacities for each sub-group. • Design for Normal Head. • Assume an overall efficiency: 90 – 94% • Calculate the required flow rate.

  9. General Layout of A Hydro Power Plant

  10. Geometry of Power Tunnel

  11. Geometry of Power Tunnel

  12. THE CONDUIT SYSTEM • Water from the storage is diverted into the main conduit system through a 3,370ft long intake channel and an intake tower, trash racks and two intake gates each 21ftX8ft. • The head race tunnel is 12,000ft long and 21ft in diameter. • It is concrete lined for the whole of the length expect for the last 1600ft at the surge end where 17ft diameter steel lining is provided. • The diameter of the tunnel, in the stretch of steel lining is reduced on ground of economy

  13. Open Channel Gravity Flow Channel Bed Slope

  14. Discharge through An Open Channel

  15. Design of Penstock In general But maximum allowable value is 10 m/s Maximum allowable head loss in Penstock =2 to 4% of available head

  16. General Design of Under Ground Power Tunnels/Penstocks

  17. Design of Penstock

  18. Distributor : Only for multi jet Wheel

  19. Design of Distributor Penstock Q

  20. The Nozzle and Jet : A Key Step in Design b a d0 djet,VC Free Surface Shape for Maximum Power

  21. Initial guess for Diameter of the Jet at the outlet, do It is important to find out the VC and outlet jet diameters/areas

  22. Geometrical Relations for Nozzle 1.1dO – 1.3dO 2dO – 2.4dO dO 0.8dO – 0.9dO 1.2dO – 1.4dO 5dO – 9dO

  23. Performance Analysis of Nozzle-Spear Valve Ideal Nozzle-spear Valve: Along flow direction Real Nozzle-spear Valve:

  24. Numerical Computation of Total Pressure Variation

  25. Efficiency of Spear Nozzle Valve Acceptable Range: 97.5% -- 99%

  26. Design of Penstock

  27. Geometrical Relations for Nozzle The values of α varies between 20 to 30° whereas β varies from 30 to 45°.

  28. Industrial Correlations for Jet Area variation with stroke Optimal value of Outlet jet area, ao s is the displacement of spear

  29. Computation of Variation Jet Area with stroke

  30. Mean Diameter of Pelton Runner Mean diameter or Pitch circle diameter: Dwheel Circumferential velocity of the wheel, Uwheel

  31. Experimental values of Wheel diameter to jet diameter Higher ratios are preferred for better efficiency. Modern wheels for high heads use ratios as high as 30!

  32. Optimal values of Wheel diameter to jet diameter Ns

  33. III II IV V I Empirical Geometry of Bucket Shape C 2bi DW S A be B

  34. Empirical Relations for Bucket Geometry • A = 2.8 djet,VC to 3.2 djet,VC • B = 2.3 djet,VC to 2.8 djet,VC • C= 0.6 djet,VC to 0.9 djet,VC • bi = 50 to 80 • be is varied from section I to section V • I: 300 to 460 • II: 200 to 300 • III: 100 to 200 • IV: 50 to 160 • V: 00 to 50

  35. d RW w RP q y dO, Vj,O lj Number of Buckets

  36. Maximum allowable angle between two successive buckets Minimum number of buckets Dr Taygun has suggested an empirical relation for z

  37. No. of Buckets

  38. Empirical Relations for Bucket Cutout • S = 0,95djet,VC to 1.05 djet,VC • d1= 0.18 djet,VC to 0.2 djet,VC • d2 = 0,95djet,VC to 1.05 djet,VC

  39. Vjet Ublade be Ublade Vrel,jet,exit Absolute and Relative Paths of Jet : Orthogonal Interactions ae Vjet,exit

  40. Define Blade Speed Ratio, f

  41. Approximate Velocity Triangles: Pelton Bucket

  42. Start of Jet Bucket Interactions

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