Selection of Turbine With Respect to Head VS Specific Speed
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The document discusses the selection of turbines based on head and specific speed. It defines turbines as devices that extract energy from fluid and describes the main types as impulse and reaction turbines. Impulse turbines use velocity to move the runner while reaction turbines develop power from pressure and moving fluid. Turbines are selected based on the specific conditions like head and flow. High head turbines operate over 250m head with low flow. Francis turbines are used for medium heads from 45-250m. Kaplan turbines are suitable for low heads under 45m with high flow. Specific speed is also used to select turbines, with low specific speed turbines like Pelton used for high heads and high specific speed propeller turbines for low heads.
Selection of Turbine With Respect to Head VS Specific Speed
- 1. Selection of turbine with respect to head versus specific speed Electrical Department Bahria university
- 2. Group Member • Junaid Maqsood • Talha Ali 2
- 3. Contents Turbine & its design Types of Turbine Types of turbine on Basis of Head Types of turbine Based on specific speed Selection of turbine Turbine Application Chart Conclusion 3
- 4. Turbine What is turbine ? •“turbo” or “turbines” is Latin in origin and implies that which spins or whirls around •Turbine is a device that extracts energy from a fluid •Energy is transferred to or from a continuously flowing fluid by the dynamic action of moving blades or rotors 4
- 7. Impulse Turbine • IMPULSE TURBINE The impulse turbine generally uses the velocity of the water to move the runner and discharges to atmospheric pressure. The water stream hits each bucket on the runner. There is no suction on the down side of the turbine, and the water flows out the bottom of the turbine housing after hitting the runner. An impulse turbine is generally Suitable for high head, low flow applications. 7
- 8. REACTION TURBINE • REACTION TURBINE A reaction turbine develops power from the combined action of pressure and moving water. The runner is placed directly in the water stream flowing over the blades rather than striking each individually. Reaction turbines are generally used for sites with lower head and higher flows than compared with the impulse turbines 8
- 9. Selection of turbine • The turbine is always selected to match the specific conditions under which it has to operate and attain the maximum possible efficiency. • Head Flow/Speed • For selection of suitable turbine, the characteristics features of common turbines based on experience are given in further slides. 9
- 10. Types of turbine on Basis of Head Based on head and quantity of water According to head and quantity of water available, the turbines can be classified into a) High head turbines b) Medium head turbines c) Low head turbines 10
- 11. Based on head and quantity of water a) High head turbines – High head turbines are the turbines which work under heads more than 250m. – The quantity of water needed in case of high head turbines is usually small. – The Pelton turbines are the usual choice for high heads. 11
- 12. Based on head and quantity of water b) Medium head turbines – The turbines that work under a head of 45m to 250m are called medium head turbines. – It requires medium flow of water. Francis turbines are used for medium heads. 12
- 13. Based on head and quantity of water c) Low head turbines – Turbines which work under a head of less than 45m are called low head turbines. – Owing to low head, large quantity of water is required. – Kaplan turbines are used for low heads. 13
- 14. Classification and Selection of turbine based on Head 14
- 15. Choice Of turbine Depends on available Head •Specific Speed: – For High Head – low specific speed so impulse turbines are required – For Low Head – High Speed e.g Propeller 15
- 16. Based on specific speed of turbines Speed of a unit power when working under unit head. It is denoted by the symbol Ns. N= Speed (RPM) P = Power developed H = head under which the turbine is working 16
- 17. Classification and Selection of turbine based on Head Specific Speed m/s Slow Medium fast 17
- 18. To Vary Specific Speed 18
- 19. Conclusion 19
Editor's Notes
- #5: 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
- #6: A simple design of a turbine contain as rotor assembly, which is the moving part, having shaft or drums with blades attached to them. The movement of the blades, which is caused by the flow of fluids, creates rotational energy which is imparted to the rotor. Some example of turbine impulse , Reaction etc.
- #7: If at the inlet of the turbine, the water possesses kinetic energy as well as pressure energy, the turbine is known as reaction turbine. If at the inlet of the turbine, the energy available is only kinetic energy, the turbine is known impulse turbine Francis turbine The Francis turbine is a radial-flow turbine with water flowing in a radial direction inward over the curved runner blades toward the centre of the turbine Propeller Turbine The vanes are fixed to the hub and they are not adjustable, the runner is known as propeller turbine. Kaplan Turbine The vanes on the hub are adjustable the turbine is known as a Kaplan turbine. This turbine is suitable where a large quantity of water at low heads is available
- #12: High head turbines are the turbines which work under heads more than 250m. The quantity of water needed in case of high head turbines is usually small. The Pelton turbines are the usual choice for high heads.
- #14: Turbines which work under a head of less than 45m are called low head turbines. Owing to low head, large quantity of water is required. Kaplan turbines are used for low heads.
- #17: It is defined as the speed of a turbine which is identical in shape, geometrical dimensions, blades angles, gate opening etc., with the actual turbine but of such a size it will develop unit power when working under unit head.
- #19: Use 1 Francis or Four Pelton Turbines, same power is generated