Braking Jet in an Impulse Turbine.

The braking jet is a special jet of water which is used to bring the impulse turbine , such as a Pelton Wheel, to a stop in a short time.

The impulse turbine works when a jet of water impinges on the buckets in the turbine.  The turbine rotates at a high speed.

When the turbine is to be stopped, the flow of water is stopped.  However, due to the momentum, the turbine will run for a long time.

In order to reduce the time taken for the turbine to come to a stop, a jet of water is made to hit the turbine from the direction opposite to the direction of rotation.

This jet of water is known as the braking jet as it applies a "brake" on the turbine.