Difference Between Impulse and Reaction Turbine
Table of Contents
Difference Between Impulse and Reaction Turbine
The key Difference Between Impulse and Reaction Turbine are highlighted in the following table −
| Basis of Difference | Impulse Turbine | Reaction Turbine |
|---|---|---|
| Definition | Impulse turbines are the kind of turbines that rotate solely using the kinetic energy of moving water (impulse force). | The reaction turbine is a type of water turbine that utilizes both the kinetic energy and the pressure energy of the water to turn the turbine. |
| Water flow | In an impulse turbine, water enters a nozzle and strikes the turbine’s blades. | In a reaction turbine, the guide blades (fixed blades) direct the water as it flows over the turbine. |
| Force on blades | In impulse turbine, an impulsive force rotates the turbine. | In reaction turbine, a reaction force on the blades is rotation the turbine. |
| Pressure of water while flowing over moving blades | When water flows over rotating blades in an impulse turbine, the pressure of the water remains constant and equal to atmospheric pressure. | Water pressure in the reaction turbine continuously drops as it passes over the blades. |
| Decrease in pressure of water | Before entering the turbine in an impulse turbine, the water’s pressure is lowered in the nozzle. | Water pressure in a reaction turbine drops as it passes over the blades. |
| Change in pressure of water | All of the water’s pressure is transformed into kinetic energy before striking the turbine blades in an impulse turbine. | The water pressure before it strikes the turbine blades in a reaction turbine is unchanged. |
| Water head | The impulse turbines are most suitable for large water heads. | The reaction turbines are suitable for relatively low water heads. |
| Water flow rate | The impulse turbines are suitable for comparatively low water flow rates. | Reaction turbines are suitable in cases where water flow rates are higher. |
| Necessity of turbine casing | Since an impulse turbine has no hydraulic function, a turbine casing is not required. It is merely offered to stop water splashing. | Because the pressure at the inlet is much higher than the pressure at the outlet, a reaction turbine needs a turbine casing. The casing thus protects it from atmospheric pressure. |
| Blades profile | The blades of an impulse turbine are of symmetrical profile. | The blades of a reaction turbine are asymmetrical, having aerofoil profile. |
| Water discharge | In an impulse turbine, the water is discharged into the tail race directly from the turbine wheel. | In a reaction turbine, the water discharges into a draft tube first and then into the tail race. |
| Turbine size | For the same power output, the size of impulse turbine is smaller. | The reaction turbine have relatively large size for the same power output. |
| Examples | Pelton wheel turbines, Turgo turbines, and cross-flow turbines are three common types of impulse turbines. | Popular examples of reaction turbines are. Francis turbine and Kaplan turbine. |
Conclusion
The main distinction between an impulse turbine and a reaction turbine is that an impulse turbine only rotates its runner using water’s kinetic energy, whereas a reaction turbine rotates its turbine using both pressure and water’s kinetic energy.