Hydraulic turbine


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detailed study of hydraulic turbines.

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Hydraulic turbine

  2. 2.  Turbines are defined as the hydraulic machines which convert hydraulic energy into mechanical energy.  This mechanical energy is used in running an electric generator which is directly coupled to the shaft of the turbine.  Thus the mechanical energy is converted into electrical energy.
  3. 3. Classification of hydraulic turbines  According to type of energy at inlet 1. Impulse turbine 2. Reaction turbine  According to direction of flow of water 1. Tangential Flow turbines 2. Axial flow turbines 3. Radial flow turbines - Inward radial flow turbine and Outward radial flow turbine 4. Mixed flow turbines Cont…
  4. 4.  According to water head and quantity of water available 1. High head & small quantity of flow of water 2. Medium head & medium flow rate 3. Low head and large flow rate  According to the specific speed of the turbine 1. Low specific speed turbine ( <60 ) ex. Pelton wheel 2. Medium specific speed turbine ( 60 to 400 ) ex. Francis turbine 3. High specific speed turbine ( above 400 )
  5. 5. • IMPULSE TURBINE If at the inlet of the turbine, the energy available is only kinetic energy, the turbine is known impulse turbine. Example: Pelton wheel turbine • REACTION TURBINE If at the inlet of the turbine , the water possesses kinetic energy as well as pressure energy, the turbine is known as reaction turbine. Example: Francis turbine , Kaplan turbine • RADIAL FLOW TURBINE If the water flow in the radial direction through the runner, the turbine is called radial flow turbine • INWARD RADIAL FLOW TURBINE If the water flows from outward to inward radially , the turbine is known as inward radial flow turbine. •OUTWARD RADIAL FLOW TURBINE If the water flow radially from inward to outwards, the turbine is known as outward radial flow turbine.
  6. 6. •AXIAL FLOW TURBINE: If the water flow through the runner along the direction parallel to the axis of rotation of the runner, the turbine is called axial flow turbine. •MIXED FLOW TURBINE: If the water flows through the runner in the radial direction but leaves in the direction parallel to axis of rotation of the runner, the turbine is called mixed flow turbine. • TANGENTIAL FLOW TURBINE: If the water flows along the tangent of the runner, the turbine is known as tangential flow turbine.
  7. 7. •Impulse turbine & Reaction turbine 1. Impulse turbine a. Water from penstock to turbine via one or more nozzle. b. Pressure energy converted into kinetic energy. c. Rotation of wheel due to tangential force created by impact of jet.
  8. 8. a. Both kinetic and pressure energy. b. Feeding of water through fixed blades in casing. c. Static pressure at inlet is greater than outlet of runner. d. Rotation due to impulse reaction and due to reduction in pressure so it is called Reaction turbine.  Reaction turbine
  9. 9. IMPULSE TURBINE REACTION TURBINE • All the potential energy is converted into kinetic energy by nozzle before entering to turbine runner. • Flow regulations is possible without loss. • Unit is installed above the tailrace. • Blades are only in action when theyare in front of nozzle. • Only a portion of the fluid energy istransferred into kinetic energy before thefluid enters the turbine. • Flow regulation is possible with loss. • Unit is kept entirely submerged in waterbelow tailrace. • Blades are in action at all the time
  10. 10. Francis turbine
  11. 11. Designed and developed by American engineer James B. Francis in 1848. Head engineer in textile factory city of Lowell Massachusetts Improved on these designs to create a turbine with 90% efficiency.
  12. 12. • Designed and developed by American engineer Janes B. Francis in184 • Inward reaction flow turbine • Water head : 10 to 650 meters • Power output range : 10 MW to 750 MW • Speed range : 83 to 1000 rpm • In Old Francis radial discharge at outlet • In Modern Francis, Water enters radially from outlet periphery and leaves the runner in the axial direction • Main components of turbine 1. Spiral Casing 2. Guide vanes 3. Runner 4, Governing mechanism 5. Draft tube • This is the most common turbine type in hydroelectric stations
  14. 14. 1. Penstock : Large diameter tube through water from dam comes to turbine inlet. It is made from steel. 2. Spiral Casing : a. It is a closed passage whose diameter gradually decreases along flow of direction. Area is maximum at inlet and nearly zero at exit. b. To maintain constant flow rate, numerous openings (wicket gates) provided. c. The purpose of casing to distribute water over guide vanes and prevent formation of eddies. d. made of cast steel, plats steel or concrete depends on head. 3. Guide vanes : a. It is aerofoil shaped vanes fixed between two rings. b. It convert a part of pressure energy into kinetic energy. c. Each guide vane can rotate about it pivot centre hence it also serves to direct the flow at design angles to the blade runners.
  15. 15. 4. Governing mechanism : It can change the position of guide vanes to vary the flow on turbine. 5. Runner : a. Profile is designed so that water enter inwards in radial direction and leave it in the axial direction. b. Runner rotate due to impulse and reaction effects. c. It is classified according to fast , medium & slow. d. Made of cast iron(small unit) , stainless steel (large unit), bronze (impure water). e. It is keyed to shaft of turbine. 6. Draft tube : a. It is gradually expanding tube which discharge water passing through the runner to tail race. b. Generally with increasing diameter in flow direction.
  16. 16. At low speed At high speed
  18. 18. •The Pelton wheel is a water tangential flow impulse turbine. • It was invented by Lester Allan Pelton an American engineer in the 1870s. • This turbine is used for high heads. • The main components of Pelton wheel or turbine. 1. Nozzle & spear 2. Runner and Bucket 3. Casing 4. Breaking jet
  20. 20. • Nozzle & spear a. Amount of water striking the bucket of water controlled by spear in the nozzle. b. Spear is conical needle which operated either by hand wheel over automatically axially depends on size of unit. •
  21. 21. • Runner a. It consists of circular disk on periphary of which number of buckets evenly spaced are fixed b. Shape of bucket is of a double hemi-spherical cup. Each bucket is divided by spiltter which divide the jet into two parts. c. Made of Cast iron or cast steel bronze or stainless steel depends on head.
  22. 22. •Casing a. Prevent spalashing of water. b. Act as a safe guard c. Made of cast iron, fabricated steel •Breaking jet •Jet of water used to stop runner in short time. •It strikes at the back of vane.
  23. 23. ThANK YOU