Comparison Between Impulse Turbine and Reaction Turbine

Sr.
No.

Impulse
Turbine

Reaction
turbine

1.

It works on the principle of impulse. Therefore, it follows the
impulse momentum equation.

It works on the principle of impulse and reaction. Therefore, it
follows the law of angular momentum.

2.

All the available head is first converted into kinetic energy in
nozzles.

Only part of available head is converted into kinetic energy in guide
vanes.

3.

Water from nozzles comes out in the form of jet which impinges on the
buckets of runner.

Water is guided by the guide blades to flow over the moving vanes.

4.

Flow of water over the runner is at constant atmospheric pressure.

Flow of water over the runner is under pressure which gradually
decreases from inlet to outlet.

5.

The runner of turbine need not run full and the water may be admitted
over the full or part of periphery of runner.

The runner needs to run of water since under pressure all the time.
Water is over the circumference of the runner.

6.

Casing is not a must. It is provided to collect the water discharged
from the turbine and directs it to tail race. It also avoids splashing of
water.

Casing is essential since water flows from inlet to outlet under
pressure.

7.

The work is done due to change in kinetic energy of jet.

Most of the work is done due to change in pressure head and very
small of work is due to change in kinetic energy.

8.

It is possible to regulate the flow of water without loss.

It is not possible to regulate the flow of water without loss.

9.

Suitable for high heads.

Suitable for low and medium heads.

10.

Head loss due to installation of turbine above tail race cannot be
recovered.

Head loss due to installation above tail race can be recovered by
using draft tube.