Difference between an impulse and a reaction turbine
Following are the few points of difference between impulse and a reaction turbine.
- The entire available energy of water is first converted into kinetic energy.
- The water flows through the nozzles and impings on the buckets which are fixed to the outer periphery of the wheel.
- The water strikes on the buckets with kinetic energy.
- The pressure of the flowing water does not change. It is equal to the atmospheric pressure.
- It is not essential that the wheel should run full. There should be free access of air between vanes and the wheel.
- The water must be admitted over a part of circumference or the over the whole circumference of the wheel.
- It is possible to regulate the flow without loss.
- The work is done by the change in kinetic energy of the jet.
- In reaction turbine, the available energy of water is not converted into one form to another.
- The water is guide by the guided blades to flow over the moving vanes.
- The water move smoothly over the moving vanes with pressure energy.
- The pressure of the flowing water is reduced after moving smoothly over the vanes.
- It is necessary that wheel should always run full, and kept full of water.
- The water must be admitted over the whole circumference of the wheel.
- It is not possible to regulate the flow without loss.
- The work is done partly by the change in velocity head. But almost all work is done by the change in pressure head.
A textbook of hydraulics, fluid mechanics and hydraulic machines by R.S. Khurmi