A Francis turbine is used for ________.

Question

Question

This question was previously asked in

SSC JE Electrical 14 Nov 2022 Shift 3 Official Paper

Answer 1

A Francis turbine is used for low to medium heads.

Classification of turbines

1.) Impulse turbine

If the turbine wheel is driven by the kinetic energy of the fluid that strikes the turbine blades through the nozzle or otherwise, the turbine is known as an impulse turbine.
In these types of turbines, a set of rotating machinery operates at atmospheric pressure.
Impulse turbines are usually suitable for high head and low flow rates.
Pelton, Turgo, and Cross-flow turbines are three types of impulse turbines.

2.) Reaction turbine

If the sum of potential energy and kinetic energy of water which is due to the pressure and velocity, respectively cause the turbine blades to rotate, the turbine is classified as a reaction turbine.
In these types of turbines, the entire turbine is immersed in water, and changes in water pressure along with the kinetic energy of the water cause power exchange.
Applications of reaction turbines are usually at lower heads and higher flow rates than impulse turbines.
Example: Francis turbine, Kaplan turbine. Propeller turbine.

Flow	Energy	Head	Example
Tangential	Impulse	High (Above 300 m)	Pelton wheel
Radial	Reaction	Low to medium (Between 30 to 300 m)	Francis turbine
Axial	Reaction	Low (less than 30 m)	Kaplan turbine, Propeller turbine