Impulse Turbine: Principle, Construction & Working

An impulse turbine is a basic type of turbine used in power generation in a hydropower plant. The term impulse means sudden force act to bring desire change. It denotes as a 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. It is mostly used at high heads. Today we will learn about principle, construction, and working of impulse turbine.


Impulse Turbine:


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 depends on the time interval and velocity of jet strikes the blades. This turbine used to rotate the generator, which produces electric power.




The number of blades is situated over the rotary. They are concave in shape. The water jet strikes at the blades and changes the direction of it. The force exerted on blades depends upon the amount of change in direction of the jet. So the blades are generally concave in shape.


The rotor which is also known as a wheel is situated on the shaft. All blades are pinned into the rotor. The force exerted on blades passes to the rotor which further rotates the shaft.


A nozzle plays the main role of generating power from the 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.


The casing is the outside is which prevent the turbine form atmosphere. The main function of the casing is to prevent discharge the water from vanes to tailrace. There is no change in the pressure of water from the nozzle to tail race so this turbine works at atmospheric pressure.

Braking nozzle:

A nozzle is provided in the opposite direction of the main nozzle. It is used to slow down or stop the wheel.


As we discussed impulse turbine works on the basic principle of impulse. Its working can be described in following points.

     * High-pressure water flow from dam (high head) to nozzle (low head).
     * This water flows through the 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 tailrace.
     * This process runs continuously until sufficient power generates. For better understanding watch the video given below on working of impulse turbine. 

Advantages & Disadvantages:


1. It can work at low discharge or at low flow rates.
2. This turbine has high efficiency.
3. An impulse turbine is flexible according to the load condition. At higher load, more than one nozzle is used.
4. They work at atmospheric pressure so no problem of leakage.
5. It is easy to assemble.


1. Large size compares to others.
2. Efficiency decreases with time.
3. It required high head which 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. If you like this article, don’t forget to share it on social networks. Subscribe our website for more informative articles. Thanks for reading it.
Impulse Turbine: Principle, Construction & Working Impulse Turbine: Principle, Construction & Working Reviewed by Admin on July 26, 2018 Rating: 5

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