The Difference Between Impulse and Reaction Turbine
Turbines are essential energy conversion devices in modern power systems. They are involved in the conversion of high-pressure steam and water to rotational forces to generate electricity. There are two types of turbines: impulse and reaction types. Although both types of turbines are utilized in today’s power systems, they have significant differences in their designs and operation methods. Below are some of the significant differences between impulse and reaction turbine.
What is an Impulse Turbine?
An impulse turbine is a type of turbine that utilizes high-velocity fluid to move a turbine blade on an unpressurized section. The turbine comprises a set of rotating blades positioned inside a stationary nozzle. The fluid flows through the nozzle onto the blade, which converts the kinetic energy of the fluid’s velocity into rotational energy. This means that the impulse turbine operates on the principle of Newton’s third law of motion, which states that for every action, there is an equal and opposite reaction. Impulse turbines are commonly used in hydroelectric power plants.
What is a Reaction Turbine?
A reaction turbine converts pressure energy into kinetic energy and then into rotational energy. In a reaction turbine, the fluid flows continuously over the blade surfaces. The turbine comprises a set of rotating blades attached to a rotor and a fixed guide vanes. The flow of the fluid through the blade causes a change in its direction, causing the rotor to turn. The direction change causes a reaction to the resultant change in fluid momentum. The reaction turbine is commonly used in various industries, including hydroelectric power plants, gas turbines, and steam turbines.
Differences between Impulse and Reaction Turbine
The major differences between impulse and reaction turbines stem from their mode of operation. An impulse turbine converts kinetic energy into rotational energy, while the reaction turbine converts pressure into rotational energy. The following are the differences between impulse and reaction turbine:
1. Design – Impulse turbines have stationary nozzles and free-moving blades, while reaction turbines have fixed guide vanes and moving blades.
2. Blades – Impulse turbine blades are entirely flat, while reaction turbine blades are curved.
3. Pressure – Impulse turbines operate on low-pressure levels, while reaction turbines require high-pressure levels.
4. Efficiency – Impulse turbines are more efficient than reaction turbines, but they require constant flow rates. Reaction turbines are less efficient, but they are not affected by constant flow rates.
5. Application – Impulse turbines find applications in hydroelectric power plants, while reaction turbines are used in gas turbines, steam turbines, and other rotational equipment.
Conclusion
The choice between impulse and reaction turbines is usually determined by the specific application or project requirements. While some projects require high-pressure levels, others require constant flow rates. It is crucial to understand the strengths and weaknesses of each type of turbine to determine which type best suits the project or application’s needs. Regardless of the application, turbines remain the backbone of our energy conversion schemes.
Table difference between impulse and reaction turbine
| Impulse Turbine | Reaction Turbine |
|---|---|
| Works on the principle of impulse | Works on the principle of reaction |
| The steam or fluid is allowed to expand through a nozzle, which generates a high velocity jet. This jet impinges on the blades of the turbine, causing it to rotate. | The steam or fluid flows over the blades of the turbine, causing a reaction force that rotates the blades. |
| Blades of an impulse turbine are usually flat and have a shape of a half-disc, mounted on a flat circular plate. The blades are aligned radially, with the shaft at the center. | Blades of a reaction turbine are usually curved, mounted on a cylindrical rotor. The blades are aligned tangentially to the rotation axis. |
| Impulse turbines are suitable for high-head applications. | Reaction turbines are suitable for low-head, high-flow applications. |
| The efficiency of an impulse turbine decreases with increasing flow rate. | The efficiency of a reaction turbine increases with increasing flow rate. |
| Impulse turbines are simpler in design and construction. | Reaction turbines are more complex in design and construction. |