What is Impulse Turbine?
An impulse turbine is a type of turbine driven by a jet of water or steam at high speed from a nozzle that is directed at the blades or blades attached to the wheel. The resulting impulse (as described in Newton's second law of motion) is generated by the rotation of the turbine and removes the moving force from the continuous flow. Before reaching the turbine, the conduction of the fluid pressure is changed at a rate by accelerating the liquid through the nozzle. Preparing this jet of fluid means that no pressure gauge is needed around the impulse turbine. A Francis turbine is a famous type of impulse turbine.
Working Principle of Impulse Turbine
The principle of operation of the impulse turbine is the basic principle of impulse. When the flow of water hits the turbine blades at its maximum speed, it creates a lot of force which is used to spin the turbine. The force depends on the time interval and the speed with which the jet hits the blade. This turbine is used to rotate the generator to produce electricity.
Working of Impulse Turbine
As discussed, the principle of operation of the impulse turbine is the basic principle of the impulse. It works can be shown with the following points.
- High-pressure water flows from the dam (high head) to the nozzle (low head).
- This water passes through a variety of nozzles, where all the pressure force is converted into kinetic energy. Create a stream of water.
- The jet of water hits the blades at high speed and rotates the rotor.
- It transfers all the moving energy from the water to the rotor, then is used to rotate the generator.
- After energy is transferred, the water arrives at the bottom of the wheel.
- This process will continue until sufficient power is generated.
Main parts of an Impulse Turbine
The impulse turbine has the following major components:
The runner consists of a disc and a cylindrical shaft in the middle, to which several curved blades are attached to the disc. Shafts and runners are generally manufactured of stainless steel. In the case of a small flow head, the flow runner is manufactured of cast iron.
A bucket is a sphere-shaped set of soil that is installed around the runner and exchanges energy between the fluid and the turbine. The jet of liquid comes out of the nozzle and hits the blades, spinning the turbine and exiting the outer edges of the blades. To the angle of impact, the change in direction of the fluid during discharge depends on the turbine design.
For maximum reinforcement, this angle should be 180 degrees. But due to considerations such as the fact that the flow from one bucket does not collide with the next bucket and does not cause it to stop, the angle is limited to an angle of approximately 170 degrees. These pliers are made of stainless steel or cast iron.
The nozzle of an impulse turbine uses to control and spray the flow of liquid to reach the bucket. As mentioned above, pressure changes and head current changes with the moving force are the only components of a turbine assembly. The volume of the jet of water that reaches the bucket is regulated by a component called a lance, a conical needle that enters and exits the nozzle via a wheelbarrow or automatically.
The nozzle usually made of tungsten carbide, which is very hard and can withstand corrosive particles.
The Impulse turbine casing is a protective cover on the turbine that prevents water splashes and directs water into the overflow. There is enough flow to protect the structural integrity of the dam. Cast iron usually uses for the casing.
Pressure pipelines in hydroelectric power plants are pipes and channels that carry water from dams and reservoirs to turbines. They usually made of steel.
Advantages & Disadvantages of Impulse Turbines
1. It can operate with a low flow or discharge rate.
2. High efficiency.
3. Pulse turbine can be selected according to load conditions. Use more than one nozzle with more load.
4. They work at atmospheric pressure, so there is no leakage problem.
5. Ease of assembly
1. Big size than other turbines.
2. Performance decreases with time.
3. High head required which is difficult.
4. The installation cost is high.
Applications of Impulse Turbines
- Used to generate electricity in many hydroelectric power plants around the world.
- The car's turbocharger harnesses the pressure of the exhaust gases through the pulse turbine. The high temperature and pressure gas discharged from the exhaust gas is produced by a high-velocity jet through the nozzle.
- It is also used in reverse osmosis devices, where the speeds of the sewer jets are used to start the turbine, thus serving as an energy recovery system.