An impulse turbine is a type of steam turbine where the rotor derives its rotational force from the impact force, or the direct push of steam on the blades.
The impulse turbine was first built in 1883 by the Swedish engineer De Laval.
The impulse turbine consists of a rotor mounted on a shaft that is free to rotate. Attached to the rotor are a set of curved blades. Nozzles then direct the high pressure and high temperature steam towards the blades of the turbines. The blades catch the impact force of the rapidly moving steam and rotate from this force.
Below is a simple diagram of impulse turbine blades:
The above diagram of impulse turbine blades shows:
(1) The steam first enters the impulse turbine through a fixed nozzle.
(2) The steam strikes the blades that are free to rotate with a strong enough force to move the blades.
(3) The steam exits the blades towards the condensing system of the steam turbine generator system.
(4) The direction of the blades due to the force of steam.
This next diagram shows the rotational force of the impulse turbine:
From the above diagram of the impulse turbine we see:
(1) The steam enters from a fixed nozzle.
(2) The steam strikes the rotating blade with enough force to spin the impulse turbine.