Reaction Turbine: Definition, Types, Component, Working Principle, Application, Advantages, Disadvantages

What is Reaction Turbine?

A reaction turbine is a type of turbine that converts the energy of a fluid into rotational energy by extracting the kinetic energy of the fluid through a series of rotating blades. Unlike impulse turbines, which operate on the principle of the high-velocity impact of a fluid on a set of stationary blades, reaction turbines operate on the principle of the reaction force generated by the fluid as it passes over a set of moving blades.

In a reaction turbine, the fluid enters the turbine through a series of fixed guide vanes, which direct the fluid onto a set of moving blades on the turbine rotor. As the fluid passes over the blades, it creates a force that causes the rotor to rotate. The blades are designed in such a way that they create a pressure difference across them, which causes the fluid to accelerate as it passes over them, thereby increasing the kinetic energy extracted from the fluid.

Reaction turbines are commonly used in hydroelectric power generation, where the energy of falling water is used to rotate the turbine rotor and generate electricity. They are also used in other power generation applications, such as steam turbine power plants, where the energy of high-pressure steam is used to drive the turbine rotor.

Overall, reaction turbines are known for their high efficiency and durability, and are widely used in a variety of power generation applications where a large amount of energy is needed to generate electricity.

Parts of Reaction Turbine

The major parts of a reaction turbine include:

1. Casing: The casing is the outer shell of the turbine that contains the rotor and other internal components. It is designed to withstand the high pressures and temperatures generated by the turbine.
2. Rotor: The rotor is the rotating part of the turbine that contains the blades. It is connected to the generator shaft and rotates at high speeds to generate mechanical energy.
3. Blades: The blades are the curved, airfoil-shaped components that extract energy from the fluid and convert it into rotational energy. They are mounted on the rotor and are designed to create a pressure difference across them to accelerate the fluid and increase the kinetic energy extracted from it.
4. Shaft: The shaft is the component that connects the rotor to the generator and transfers the mechanical energy generated by the turbine to the generator to produce electricity.
5. Bearings: The bearings support the shaft and allow it to rotate freely. They are designed to withstand the high speeds and loads generated by the turbine.
6. Inlet guide vanes: The inlet guide vanes are fixed vanes located at the entrance of the turbine. They direct the fluid onto the blades at the correct angle to maximize energy extraction.
7. Draft tube: The draft tube is a conical-shaped tube located at the exit of the turbine. It helps to reduce the fluid velocity and recover some of the kinetic energy that would otherwise be lost as the fluid exits the turbine.

These are the major parts of a reaction turbine, although there may be other components depending on the specific design and application of the turbine.

Working of Reaction Turbine

The working of a reaction turbine can be explained as follows:

1. The fluid (usually water) enters the turbine casing through an inlet and flows through the fixed guide vanes that direct it onto the moving blades of the rotor.
2. As the fluid passes over the blades, it exerts a force on them, causing the rotor to rotate. The blades are designed such that they create a pressure difference across them, which causes the fluid to accelerate and increase the kinetic energy extracted from it.
3. The fluid then exits the turbine through the draft tube, which helps to reduce the fluid velocity and recover some of the kinetic energy that would otherwise be lost as the fluid exits the turbine.
4. The rotation of the rotor is transmitted to the generator shaft, which generates electricity through electromagnetic induction.
5. The electricity generated is then transmitted to the electrical grid for distribution to consumers.

The efficiency of a reaction turbine depends on various factors, including the fluid flow rate, the design of the turbine blades, the number of stages, and the size of the turbine. Reaction turbines are known for their high efficiency and durability, and are widely used in a variety of power generation applications, such as hydroelectric power plants and steam turbine power plants.

Types of Reaction Turbine

There are several types of reaction turbines, including:

1. Francis turbine: This is the most common type of reaction turbine, and is suitable for medium to high head applications. It has a mixed flow design, with both radial and axial flow of the fluid. The fluid enters the turbine through a spiral casing, and flows over fixed guide vanes and onto the rotating blades of the rotor.
2. Kaplan turbine: This is a propeller-type reaction turbine that is suitable for low head applications. It has adjustable blades that can be adjusted to optimize efficiency over a wide range of operating conditions.
3. Propeller turbine: This is a simple type of reaction turbine that has a fixed pitch propeller as the rotor. It is suitable for low head applications, and has a high flow rate and low efficiency.
4. Bulb turbine: This is a compact type of reaction turbine that is suitable for low head applications. It has a horizontal axis and is mounted directly on the generator, which makes it easy to install and maintain.
5. Tubular turbine: This is a type of reaction turbine that has a vertical axis and is suitable for low head applications. It has a compact design and is often used in small hydroelectric power plants.

Each type of reaction turbine has its own advantages and disadvantages, and is suitable for different applications depending on the head, flow rate, and other operating conditions of the fluid.

Advantages and Disadvantages of Reaction Turbine

Advantages of Reaction Turbine:

1. High efficiency: Reaction turbines are known for their high efficiency, especially in comparison to other types of turbines.
2. Wide range of applications: Reaction turbines are suitable for a wide range of applications, from low head to high head and from small to large scale.
3. Low maintenance: Reaction turbines have a simple design and are relatively easy to maintain, which makes them cost-effective in the long run.
4. Reliable: Reaction turbines have a proven track record of reliability, which is important for applications where downtime can be costly.

Disadvantages of Reaction Turbine:

1. Complex design: The design of reaction turbines is more complex than that of impulse turbines, which can make them more difficult to manufacture and repair.
2. High cost: Reaction turbines are often more expensive than other types of turbines due to their complex design and high efficiency.
3. Limited control: The performance of a reaction turbine is largely dependent on the flow rate and pressure of the fluid, which can be difficult to control in some applications.
4. Vulnerable to damage: The blades of reaction turbines can be damaged by debris in the fluid, which can result in costly repairs or downtime.

Overall, the advantages of reaction turbines generally outweigh the disadvantages, especially in applications where high efficiency and reliability are important.

Applications of Reaction Turbine

Reaction turbines are commonly used in hydroelectric power plants to generate electricity from the flow of water. They are also used in other industries, such as:

1. Pumps and compressors: Reaction turbines are used in pumps and compressors to convert the energy of the fluid into mechanical energy.
2. Marine propulsion: Reaction turbines are used in marine propulsion systems, where they convert the energy of the fluid into rotational energy to drive the propeller.
3. Gas turbines: Reaction turbines are used in gas turbines to convert the energy of the expanding gas into mechanical energy.
4. Wind turbines: Some types of wind turbines use reaction turbines to convert the energy of the wind into mechanical energy.
5. Paper and pulp industry: Reaction turbines are used in the paper and pulp industry to power the machines that process wood into paper and other products.

The specific application of a reaction turbine depends on the type of turbine, the head and flow rate of the fluid, and other operating conditions.

Difference Between Reaction Turbine and Impulse Turbine

The main difference between a reaction turbine and an impulse turbine is the way they convert the energy of the fluid into mechanical energy.

In an impulse turbine, the fluid is directed onto the blades of the rotor in a series of high velocity jets, which impact the blades and cause them to rotate. The rotor is designed to extract energy from the fluid in the form of kinetic energy, and as a result, the pressure of the fluid decreases as it passes through the turbine.

In a reaction turbine, the fluid is directed onto the blades of the rotor in a way that allows the fluid to flow over the blades and cause them to rotate. The rotor is designed to extract energy from the fluid in the form of both kinetic energy and pressure energy, and as a result, the pressure of the fluid remains relatively constant as it passes through the turbine.

Another key difference between the two types of turbines is their suitability for different applications. Impulse turbines are typically used in high head applications, where the fluid has a high velocity and low flow rate, while reaction turbines are typically used in low head applications, where the fluid has a low velocity and high flow rate.

In summary, impulse turbines extract energy from the fluid in the form of kinetic energy, while reaction turbines extract energy from the fluid in the form of both kinetic energy and pressure energy. The choice between the two types of turbines depends on the specific application and the characteristics of the fluid being used.

Reaction Turbine Example

A Francis turbine is a common example of a reaction turbine. It is widely used in hydropower plants for generating electricity from water. The turbine was invented by American engineer James B. Francis in the mid-1800s.

The Francis turbine has a series of curved blades that are fixed to a rotating shaft. Water enters the turbine through the stationary guide vanes and flows through the runner blades. The shape of the blades causes the water to change direction and accelerate as it passes through the turbine. The pressure drop across the turbine causes the turbine to rotate, which drives a generator to produce electricity.

Francis turbines are known for their efficiency and flexibility, as they can operate over a wide range of flow rates and water head conditions. They are used in a variety of applications, including hydroelectric power plants, irrigation systems, and water treatment facilities.

Read More: Impulse Turbine: Definition, Types, Component, Working Principle, Application, Advantages, Disadvantages