Impulse vs Reaction Turbine: Difference and Comparison

Key Takeaways

1. Impulse turbines are hydraulic turbines used to generate mechanical energy from water or steam.
2. Reaction turbines are a class of hydraulic turbines used for converting the potential energy of a fluid into mechanical work.
3. The impulse turbine operates at atmospheric pressure at the exit of the turbine, while the reaction turbine maintains a relatively constant pressure as the fluid flows through the rotor.

What is an Impulse Turbine?

Impulse Turbines are hydraulic turbines that generate mechanical energy from water or steam. They operate on converting the kinetic energy from a high-velocity fluid jet into mechanical work. These are commonly used in hydroelectric power plants and steam turbines for power generation.

Impulse turbines are designed to handle high-speed, high-pressure fluid flows, making them suitable for applications with a high head of water. The main components of an impulse turbine include a set of stationary nozzles or guide vanes and a set of rotating blades or buckets.

One of the distinguishing features of impulse turbines is that they operate at atmospheric pressure at the exit of the turbine. The high-pressure water or steam is directed through a series of nozzles, which increases the fluid’s velocity and reduces its pressure.

What is a Reaction Turbine?

Reaction turbines are a class of hydraulic turbines used for converting the potential energy of a fluid into mechanical work. These turbines are commonly employed in applications with lower heads and are essential components in hydropower plants.

Reaction turbines are designed to work with fluids at a relatively constant pressure as they pass through the turbine. These turbines are distinguished by their enclosed runner design, surrounded by a casing.

One of the primary advantages of reaction turbines is their ability to operate on applications with a wide range of head and flow conditions. The efficiency of reaction turbines is influenced by factors such as the runner blades’ design, the casting’s shape, and the fluid’s flow rate.

Difference Between Impulse and Reaction Turbines

1. Impulse turbines operate on the principle of converting the kinetic energy of high-velocity fluid jets into mechanical energy. In contrast, reaction turbines work by reacting to the pressure and flow of the fluid.
2. The impulse turbine operates at atmospheric pressure at the exit of the turbine, while the reaction turbine maintains a relatively constant pressure as the fluid flows through the rotor.
3. Impulse turbines have open runners with blades not enclosed by a casing, while reaction turbines have held runners surrounded by a casing.
4. Impulse turbine runners feature flat or slightly curved blades that direct the fluid in a specific direction. In contrast, reaction turbine runners have curved blades designed to optimize fluid flow and extract energy from it.
5. Impulse turbines use nozzles to increase the fluid’s velocity before it impacts the blades. In contrast, the reaction turbines do not rely on nozzles to accelerate the fluid as they work by changing its momentum as it flows over the runner blades.

Comparison Between Impulse and Reaction Turbine

Parameters	Impulse Turbine	Reaction Turbine
Working Principle	Converting the kinetic energy of high-velocity fluid jets into mechanical energy	Work by reacting to the pressure and flow of fluid
Pressure Variation	Operates at atmospheric pressure at the exit of the turbine	Maintains a constant pressure as the fluid flows through the rotor
Runner Design	Open runners with blades that are not enclosed by casing	Enclosed runners surrounded by a casing
Runner Shape	Flat or slightly curved blades that direct fluid in a specific direction	Have curved blades designed to optimize the flow of the fluid
Use of nozzles	To increase fluid’s velocity	Do not rely on nozzles to accelerate the fluid

References

1. https://www.sciencedirect.com/science/article/pii/S096014812030968X
2. https://www.sciencedirect.com/science/article/pii/0038092X58900471