IMPULSE TURBINE

FPE PPT

1. Babaria Institute Of Technology Impulse Turbine Prepared By: Antala Brijesh -150050119009

2. What is a Turbine…? A machine for producing continuous power in which a wheel or rotor, typically fitted with vanes, is made to revolve by a fast-moving flow of water, steam, gas, air, or other fluid. This mechanical energy is used in running an electric generator which is directly coupled to shaft of the turbine. Thus mechanical energy is converted to electrical energy.

3. CLASSIFICATION OF TURBINE According to type of energy at inlet. According to direction of flow through runner. According to head at the inlet of turbine. According to specific speed of turbine .

4. ACCORDING TO TYPE OF ENERGY AT INLET On basis of the type of energy at inlet turbine can be classified in two types. Impulse turbine Reaction turbine

5. IMPULSE TURBINE Impulse turbine is the one in which the available hydraulic energy is first converted into kinetic energy by means of efficient nozzle. High velocity jet issuing from the nozzle then strikes a series of buckets fixed around the rim of wheel(runner). The buckets change the direction of jet without changing its pressure. The resulting change in momentum sets bucket and wheel into rotary motion and thus mechanical energy is made available at the turbine shaft.

6. PELTON WHEEL TURBINE A pelton wheel is a free jet impulse turbine named after the American engineer Lester Pelton (1829-1908) .It is simple and the only hydraulic turbine ,which operates efficiently and is invariably used for heads in excess of 450m . Smooth running and good performance are the other common features of this unit.

7. DESCRIPTION OF PELTON IMPULSE TURBINE PENSTOCK - It is a large size conduit which conveys water from high level reservoir to the turbine . The penstock may be of wood ,concrete ,or steel. SPEAR AND NOZZLE -Nozzle is used to convert hydraulic energy into kinetic energy .Spear is so arranged that it can move forward or backward there by decreasing or increasing the annular area of nozzle passage.

8. CASING -Casing is provided to prevent strong splash of water ,which scatter in all directions and to guide the water to the tail race. This casing also acts as a safeguard against accidents. RUNNER WITH BUCKET- The turbine rotor, called the runner , is a circular disk carrying a number of cup shaped buckets which are arranged equidistantly around the periphery of the disk . For low heads the buckets are made of cast iron ,but for higher heads they are made of bronze ,cast steel,or stainless steel. BREAKING JET -when the nozzle is completely closed ,the amount of water striking the runner reduces to zero. But the runner due to inertia goes on revolving for long time . To stop the runner in short time , a small nozzle is provided which directs the jet of water on the back of vanes . This jet of water is called breaking jet.

9. NUMBER OF BUCKETS The number of buckets should be few as possible so that there is little loss due to friction. The jet of water must be fully utilized so that no water from the jet goes waste i.e no water escapes without striking the buckets . Jet ratio m represents the ratio of the pitch circle diameter to the jet diameter. (m=D/d) For maximum hydraulic efficiency ,the jet ratio lies between 11 and 15 and normally a jet ratio of 12 is adopted.

10. POWER WATER POWER- The power supplied by the water jet is called as water power, WP. Power supplied by jet= wQH = pgQH where Q is the discharge supplied by water jet in cubic meter per sec,and H is the net or effective head in . BUCKET POWER- The power developed at the turbine buckets is called as bucket power,BP . The power delivered by the bucket wheel is =m(V u1 +V u2 )u

11. EFFICIENCY OVERALL EFFICIENCY =power available at the turbine shaft/power available from the water jet n 0= shaft power/water power=P/ wQH HYDRAULIC EFFICIENCY = work done per sec/ k.e per second n h =((V u1 +V u2 )u)/ gH VOLUMETRIC EFFICIENCY = Volume of water actually striking the buckets/total water supplied by the jet = n v = Q a /Q=Q-q/Q MECHANICAL EFFICIENCY =shaft power/water power=P/ wQ a H

12. Thank You