Impulse reaction turbine – Impulse and reaction turbine.

Here we are going to discuss about impulse reaction turbine and its difference and classification of turbine.

Turbine definition 

Turbine is a mechanical device which is used to convert the steam energy into mechanical energy.

There are two types of turbines and that is

1. Water turbine
2. Steam turbine

• Steam energies is

1. Impulse turbine
2. Reaction turbine

For Thermodynamics mechanical engineering

For Explain cochran boiler

Impulse and reaction turbine

Impulse turbine : In a simple impulse turbine jets of the steams with high velocity are directed by one or more number of nozzles against a number of blades fitted on a  disc mounted shaft rotates due to the impulse force exhausted by the steam jets on the bleads.

Reaction turbine : In a reaction turbine steam enters the wheel under pressure and flow over the blades, the steam while glides it propels the blades and make them to move, the shaft rotates due to the reactive forces of the steam jets.

In case of impulse turbine the pressure decreases in the fixed blade and remains constant in the moving blade , but in case of reaction turbine the pressure decreases in the fixed blade as well as in the moving blade.

In case of impulse turbine the velocity of the steam increases in the fixed blade and decrease in the moving blade so as well in the reaction turbine.

Define nozzle

It is a device that converts the pressure energy into kinetic energy.

Impulse and reaction turbine difference

Impulse turbine –

1. In case of impulse turbine the steam flows through nozzles and impinges on the moving blade.
2. The steam impinges ( strikes ) on the bucket with the kinetic energy.
3. In impulse turbine blades are symmetrical in case of impulse turbine.
4. The steam pressure remains constant during its flow through the moving blade.
5. The number of stages required are less, for same power developed.
6. The blade speed and the steam speed are large due to the large pressure drop.
7. Frictional losses are greater than leakage losses.
8. Therefore impulse turbines are suitable for small power.

Reaction turbine –

1. In case of reaction turbine the steam flow through the guided mechanism and then through the moving blades.
2. The steam glides on the moving blade with pressure and kinetic energy.
3. In reaction turbine blades are not symmetrical in shape.
4. The steam pressure reduces during its through to the moving blade.
5. The number of steps required to develop some power is greater.
6. The blade speed and steam speed are small due to small pressure drop.
7. Leakage losses are more than friction losses.
8. Therefore reaction turbine are suitable for medium and high power.

classify turbines

 (1) According to the mode of steam action

1. Impulse turbine 
2. Reaction turbine

 (2) According to the flow of steam

1. Axial
2. Radial

• If the steam flow inside the casing is parallel to the axis of the rotor shaft, then that type of turbine is known as an axial flow turbine.
• If steam flows radially inside the casing, that type of turbine is known as a radial flow turbine.

 (3) According to the condition of exhaust steam

1. Condensing turbine
2. Non-Condensing turbine

 (4) According to the steam pressure

1. High pressure turbine
2. Medium pressure turbine
3. Low pressure turbine

• Low pressure and medium pressure turbines are mostly use.

 (5) According to the number of stages

1. Single stage turbine
2. Multistage turbine

NOTE –  There are 3 type of turbine blades and that is 

1. Fixed blade
2. Moving blade
3. Guide blade

But 2 blades are commonly use that is Fixed blade and Moving blade.