An impulse turbine is a famous type of turbine that drives by a high-speed jet of steam or water from a nozzle guided at a bucket or blade connected to a wheel. The resulting momentum (as explained in Newton’s second law of motion) turns the turbine and eliminates K.E by the flowing liquid. Before reaching the turbine, the fluid pressure head converts to a velocity head by increase the speed of the fluid through the nozzle. With this fluid jet preparation, the pressure around the impulse turbine does not have to be relieved.
Impulse Turbine Working Principle
In an impulse turbine, the stationary pressure in the impeller is constant, and the impeller of the turbine is at atmospheric pressure. The impeller rotates in the air, and the liquid sprays by the nozzles onto the vanes, exchanging power with the turbine. A jet nozzle guides a high-speed stream onto the vanes. These vanes mostly have cups or buckets shape. Due to this, only pressure variations appear at the nozzle.
The curved buckets use to alter the flow rate velocity. This impact creates a variation in momentum, and, by the law of energy conversion, it exerts a force on the turbine buckets. By Newton’s 2nd law of motion, a force obtained by moving a liquid varies on two features: the mass of the liquid arriving in the turbine and the change in liquid velocity between the suction and discharge of the turbine. Since the mass of the fluid has not changed, only the change in speed is taken into account when calculating the force in the flow path.
Therefore, the following steps are carried out during the power generation process of the pulse turbine.
- Stored liquid moves from the upstream water source by the penstock and is directed to the nozzle.
- The P.E of the liquid in the nozzle converts into K.E. This K.E injects into the turbine vanes after that impeller starts moving.
- There is a method to handling the liquid flow that is injected into the impeller. Spears often play a vital role during this procedure.
- A generator mounted on a shaft converts mechanical energy into electricity.