Impulse turbine is basic type of turbine used in power generation
in hydro power plant. The term impulse means
sudden force act to bring desire change. It denote as product of force and time
interval for which it acts. The impulse shows the total result of applying
force. Impulse turbine works on the same principle.
ALSO READ : DIFFERENCE BETWEEN IMPULSE AND REACTION TURBINE
Impulse Turbine:
Principle:
Impulse turbine works on the basic principle of impulse. When
the jet of water strikes at the turbine blade with full of its speed, it generates
a large force which used to rotate the turbine. The force is depends on the
time interval and velocity of jet strikes the blades. This turbine used to rotate the generator, which produces electric power.
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IMPULSE TURBINE |
Construction:
Blades:
The number of blades is situated over the rotary. They are
concave in shape. The water jet strikes at the blades and change the direction
of it. The force exerted on blades depends upon amount of change in direction of
jet. So the blades are generally concave in shape.
Rotor:
Rotor which is also known as wheel is situated on the shaft.
All blades are pined into the rotor. The force exerted on blades passes to the rotor
which further rotates the shaft.
Nozzle:
A nozzle play main role of generating power from impulse
turbine. It is a diverging nozzle which converts all pressure energy of water
into kinetic energy and forms the water jet. This high speed water strikes the
blades and rotates it.
Casing:
Casing is the outside are which prevent the turbine form
atmosphere. The main function of casing is to prevent discharge the water from
vanes to tail race. There is no change in pressure of water from nozzle to tail
race so this turbine works at atmospheric pressure.
Braking nozzle:
A nozzle is provided in opposite direction of main nozzle.
It is used to slow down or stop the wheel.
Working:
As we discussed impulse turbine works on basic principle of
impulse. Its working can be describe in following points.
* This water flows through divergent nozzle where it’s all pressure energy change into kinetic energy. It forms a water jet.
* The water jet strikes the blade at high speed which rotates
the rotor.
* It transfers all kinetic energy of water to the rotor, which further use to rotate the generator.
* After transferring energy, water flows to the tail race.
* This process run continuously until sufficient power generates.
For better understanding watch the video given below on working of impulse turbine.
Advantages & Disadvantages:
Advantage:
1. It can works at low discharge or at low flow rates.
2. This turbine has high efficiency.
3. Impulse turbine is flexible according to the load condition. At higher
load more than one nozzle are used.
4. They work at atmospheric pressure so no problem of leakage.
5. It is easy to assemble.
Disadvantages:
1. Large size compare to others.
2. Efficiency decreases with time.
3. It required high head witch is hard to control.
4. It is costly to install.
We have discussed principle, construction and working of impulse turbine. If you have any query, ask by commenting.