What are the types of Reaction Turbines? | An-Overview
A reaction turbine is a type of turbine that develops torque by responding to gas or liquid pressure or mass. The operation of reaction turbines is explained by Newton’s third law of motion (action and reaction equal and opposite).
In a reaction turbine, water enters the wheel under pressure and flows over the van, because the water flows over the van, under pressure, so the wheel of the turbine moves completely and it sinks or sinks under the tires or discharges. Weather.
Types of Reaction turbines
Reaction turbines have the following three major types:
1) FrancisTubine
Francis Turbine Medium head (10–650 m) and reaction turbine used for medium flow. Output power ranges from 10 MW to 750 MW. These turbines are in the category of medium-specific speed turbines. The main components of these turbines are the spiral case, stay vane, guide vane, runners, and draft tubes.
Since the spiral case distributes water around the wheel and its cross-sectional area gradually decreases, it does not allow the water velocity to decrease. The wheel is guided by the flow van. Guide vans are responsible for changes in water direction and speed during changes in flow rate.
Finally, the energy conversion takes place in the runner section. The draft tube also acts as an outlet to raise the net head by raising the exit water level.
The wheels of these turbines are either radial or inward mixed. The higher the specific speed, the closer the wheel is to the mixed flow. The axes of these turbines are made vertically or horizontally; The horizontal type is used for low power and small power plants.
2) Kaplan Turbines
Kaplan turbine is a type of reaction turbine. Kaplan turbines are used for low head and high flow rates. The main components of these turbines are the spiral case, stay vane, wicket gates, runners and draft tubes. Water flows radially into the guide regulator. The spire, blade, and moving van Francis operate similarly to the turbine. Unlike a propeller, the blades are adjustable on the kaplan. Therefore, by adjusting the guide vans and blades, the flow rate can be changed to maintain efficiency.
The Kaplan turbine, whose wheel is axial, is mounted vertically for high power and horizontally for low power and low head.
The specific speed of these turbines is 2 to 3 times higher than that of the Francis and is classified in the category of high specific speed turbines.
The capacity chart of these turbines, unlike Flat and Francis, can sustain its capacity over a wide range of currents.
The number of blades ranged from 3 to 6, much less than Francis’ 11 to 17.
3) Propeller Turbines
A propeller turbine usually has a runner with three to six blades in which water is in constant contact with all blades. Image of a boat propeller running on a pipe. Through the pipe, the pressure is constant; If it is not, the runner becomes out of balance. The pitch of the blade can be fixed or adjusted. Apart from the runner, the main parts are the scroll case, the wicket gate, and the draft tube.
4) Kinetic Turbines
Kinetic energy turbines, also known as free-flow turbines, generate electricity from kinetic energy in running water, rather than from the head. The systems can operate on rivers, man-made routes, tidal water or ocean currents. Kinetic systems use the natural path of water flow. They do not need to divert water through man-made routes, riverbanks, or pipes, although there may be applications in such a canal. Kinetic systems do not require large civic contributions; However, they can use existing structures such as bridges, tailrails, and channels.
