What is Reaction Turbine ? Parts, Working, Types Explained in detail [Notes & PDF]

what is reaction turbine

A reaction turbine is a type of turbine used in various applications, including power generation and hydroelectric plants. It operates based on the principle of fluid dynamics, specifically the reaction of moving fluid or gas as it passes through the turbine blades.

In a reaction turbine, the fluid (typically steam or water) enters the turbine at high pressure and high velocity. As the fluid flows through the blades, its pressure and velocity gradually decrease, while the turbine’s rotor extracts energy from the fluid to produce mechanical work.

The key characteristic of a reaction turbine is that both pressure and velocity changes occur across the blades. This is in contrast to an impulse turbine, where only velocity changes occur. The pressure drop across the blades in a reaction turbine is accompanied by a reaction force that helps generate torque and drive the rotor.

The design of a reaction turbine typically consists of multiple stages, each comprising rows of fixed and moving blades. The fixed blades, called stator or guide vanes, direct the flow of the fluid and convert its pressure into kinetic energy. The moving blades, called rotor blades, extract energy from the fluid by converting its kinetic energy into rotational motion.

The efficiency of a reaction turbine depends on factors such as the design of the blades, the pressure and velocity of the fluid, and the overall turbine configuration. Reaction turbines are commonly used in power plants where large amounts of energy need to be generated, such as in steam turbines or hydroelectric turbines.

Overall, reaction turbines play a crucial role in converting the energy of fluids into useful mechanical work, making them essential in various industrial and power generation applications.

reaction turbine parts

The following parts of the Reaction turbine are following:

1. Guide Vane: The guide vane, also known as the wicket gate, is an essential stationary component present in reaction turbines. Its primary function is to regulate and control the flow of the incoming fluid or steam towards the runner blades. By strategically positioning the guide vanes, the angle and velocity of the working fluid can be manipulated to optimise the turbine’s performance. The guide vanes are typically adjustable, allowing for precise control over the flow and ensuring that the fluid enters the runner at the most favorable angle for energy conversion. This adjustability enables the turbine to operate efficiently across a range of operating conditions.

2. Draft Tube: The draft tube is a crucial component situated at the exit of the runner in a reaction turbine. Its primary purpose is to convert the kinetic energy of the fluid leaving the runner into pressure energy. The draft tube gradually expands in diameter from the runner outlet to the discharge point, creating a cone-shaped structure. This expansion allows the fluid to decelerate while increasing its pressure, thereby preventing the formation of undesired pressure differences and minimizing energy losses. By efficiently converting kinetic energy to pressure energy, the draft tube helps to improve the overall efficiency and performance of the turbine.

3. Spiral Casing: The spiral casing is a curvilinear casing that surrounds the runner of a reaction turbine. It serves as the outer housing of the turbine and incorporates the guide vanes. The spiral casing is designed to efficiently guide the incoming fluid or steam from the penstock (the pipe that delivers the working fluid to the turbine) towards the guide vanes. Its spiral shape enables a smooth and gradual transition of the fluid from a high-pressure, low-velocity state to a lower-pressure, higher-velocity state as it enters the runner. This gradual transformation minimizes turbulence and associated energy losses, facilitating optimal energy conversion and enhancing the overall efficiency of the turbine.

4. Runner: The runner is the central rotating component in a reaction turbine, often referred to as the “heart” of the turbine. It consists of multiple blades or buckets that are attached to a central hub. The runner is directly driven by the fluid or steam and is responsible for converting the kinetic energy of the working fluid into mechanical energy. As the fluid flows through the runner, it imparts a force on the blades, causing the runner to rotate. The design of the runner blades is optimized to efficiently extract the maximum amount of energy from the fluid. Runners can have different configurations and blade shapes, such as Francis, Kaplan, or Pelton, depending on the specific application and working fluid characteristics.

5. Volute: The volute is a component found in certain types of reaction turbines, particularly in centrifugal or radial flow turbines. It is a spiral-shaped casing that surrounds the runner and aids in the efficient conversion of the fluid’s kinetic energy into pressure energy. The volute serves as a diffuser, gradually expanding in diameter as the fluid flows from the runner outlet to the discharge point. This expansion reduces the fluid’s velocity while increasing its pressure, facilitating a smoother energy conversion process. The volute is designed to minimize turbulence and associated energy losses, thereby promoting optimal efficiency in the turbine and ensuring effective energy extraction from the working fluid.

working principle of reaction turbine

A reaction turbine operates based on the principle of Newton’s third law of motion, which states that for every action, there is an equal and opposite reaction. It utilizes the reaction force created when a high-velocity fluid or steam passes through the turbine blades, resulting in the rotation of the turbine runner.

The working principle of a reaction turbine can be understood based on the following explanation:

In a reaction turbine, the rotor consists of a moving nozzle and high-pressure water or fluid is directed through the nozzle. As the water exits the nozzle, it experiences a reaction force, which in turn causes the rotor to rotate at a high speed. This concept helps us comprehend the working principle of the reaction turbine.

The impeller blades within the turbine also experience reaction forces generated by the fluid passing over them. These reaction forces result in the rotation of the impellers. After interacting with the impeller blades, the fluid flows into the grooves and eventually reaches the draft tube, which leads to the tailrace.

By employing a rotor with a moving nozzle and high-pressure water or fluid, we can better grasp the working principle of a reaction turbine. The nozzle receives a reaction force when the fluid is expelled from it, leading to the rotation of the rotor at a high speed. Similarly, in a reaction turbine, the movement of fluid over the runner blades generates a reaction force. This reaction force causes the runner to rotate. Subsequently, the fluid exits the runner blades and enters the draft tube before finally reaching the tailrace.

In summary, the working principle of a reaction turbine involves the generation of reaction forces by the fluid as it passes through the moving components of the turbine. These reaction forces drive the rotation of the rotor or runner, enabling the conversion of fluid energy into mechanical energy.

How does Reaction Turbine works?

Here’s a step-by-step explanation of how a reaction turbine works:

Overall, a reaction turbine harnesses the energy of a high-velocity fluid or steam by converting its kinetic energy into mechanical energy through the interaction of the fluid with the rotating runner blades. This rotational motion can be utilised to generate electricity, drive machinery, or perform other useful tasks.

Types of Reaction Turbine

There are several types of reaction turbines commonly used in various applications. Here are some of the most prominent types:

These are just a few examples of the various types of reaction turbines used in different settings. The choice of turbine type depends on factors such as head, flow rate, available resources, and specific project requirements. Each type of turbine is designed to optimize energy conversion and performance under specific operating conditions.

applications of reaction turbine

Reaction turbines are widely used in various industries and applications due to their efficient and versatile nature. Here are some common applications of reaction turbines:

These are just a few examples of the many applications of reaction turbines. Their efficiency, reliability, and ability to convert fluid energy into mechanical energy make them invaluable in various industries that require the conversion or transfer of power.

advantages of reaction turbine

Reaction turbines offer several advantages compared to other types of turbines. Here are some key advantages of reaction turbines:

Overall, the high efficiency, compact design, smooth operation, flexibility, and other advantages make reaction turbines a preferred choice in various industries where reliable and efficient power generation or fluid energy conversion is required.

disadvantages of reaction turbine

While reaction turbines offer numerous advantages, they also have a few disadvantages that should be considered. Here are some of the disadvantages of reaction turbines:

It is important to note that the disadvantages mentioned above are general considerations and may vary depending on the specific design, application, and operating conditions of the reaction turbine. Manufacturers and engineers continuously work to address these challenges and improve the performance and reliability of reaction turbines in various industries.

difference between impulse and reaction turbine

Here’s a table outlining the key differences between impulse and reaction turbines:

CriteriaImpulse TurbineReaction Turbine
Working PrincipleUtilizes high-velocity jets of fluid to generate powerHarnesses the reaction force of fluid passing through the blades
Runner DesignPelton wheel or similar designBlades or buckets are fixed on the runner
Flow PathFluid passes through nozzles and strikes bucketsFluid flows over blades or buckets and changes direction
Pressure DropLarge pressure drop across nozzlesModerate pressure drop across the runner
EfficiencyEfficient for high head and low flow rateEfficient for medium to high head and varying flow rate
ApplicationsSuitable for high head applicationsSuitable for a wide range of head and flow rate applications
Example TurbinesPelton turbine, Turgo turbineFrancis turbine, Kaplan turbine, Deriaz turbine, Tubular turbine

It’s important to note that while the table highlights some general differences between impulse and reaction turbines, there may be variations and specific characteristics within each type of turbine depending on design variations and specific applications.

reaction turbine example

1. Francis Turbine: Widely used for medium to high head applications in hydroelectric power plants.

2. Kaplan Turbine: Designed for low head applications with high flow rates, commonly used in river-based or tidal power generation projects.

3. Pelton Turbine: Impulse reaction turbine extracting energy from high-velocity water jets, suitable for high head applications.

4. Deriaz Turbine: Axial flow reaction turbine for low to medium head applications in hydropower projects and industrial applications.

5. Tubular Turbine: Efficient reaction turbine for medium to high head applications, commonly used in large-scale hydropower plants.

Reference : https://www.sciencedirect.com/topics/engineering/reaction-turbine

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