What is a runner in turbine?
The runner is the heart of the turbine. This is where water power is transformed into the rotational force that drives the generator. Regardless of the runner type, its buckets or blades are responsible for capturing the most possible energy from the water.
What is the order of blades in a Francis turbine runner?
Working mechanism of a Francis turbine: The turbine consists of an outer spiral casing, followed by a set of fixed blades called stay vanes, next comes a set of moving blades called guide vanes, then a set of centrally placed blades called runner and lastly an outgoing duct called draft tube.
Which turbine is Francis turbine?
reaction turbine
The Francis turbine is a reaction turbine, which means that the working fluid changes pressure as it moves through the turbine, giving up its energy. The turbine is located between the high-pressure water source and the low-pressure water exit, usually at the base of a dam.
What is the water flow direction in the runner in a Francis turbine?
What is the water flow direction in the runner in a Francis turbine? Explanation: Francis turbine is radial flow reaction turbine. Though the water enters the turbine tangentially, it enters the runner radially inward and flows outward along the axis of the runner.
Why is Francis turbine used?
Francis turbines are used frequently in hydroelectric power plants. In these plants, high pressure water enters the turbine through the snail-shell casing (the volute). This lowers the pressure as the water curls through the tube, but the speed of the water is maintained.
Which turbine is used for low discharge?
Pelton Turbine Pelton turbines are generally used for very high heads and low flows.
What kind of runner does a Francis turbine have?
Francis turbines are the most well-known type of reaction turbines. This turbine has a radial flow runner or a mixed radial/axial flow runner. Radial water flow to the runner and axial emerge as a result of the runner spinning. Wicket gates and a draft tube are two other main elements of the Francis turbine.
Which is better horizontal or vertical Francis turbine?
Francis turbine can be designed in either vertical or horizontal shaft setup. The main advantage of a horizontal unit with Francis turbine is compact design, competitive price and simple assembly and maintenance. But since such horizontal configuration has a limited capacity and size, the vertical setup is preferred for large units.
How big is the GE Francis hydro turbine?
GE has successfully completed numerous installations of Francis turbines with outputs up to 800 MW, including one of the largest Francis turbines ever made – each with a runner diameter of 10 meters and weighing over 450 tons. Francis turbines are very able to sustain the high mechanical stress resulting from high heads.
How is the exit tube of a Francis turbine shaped?
The turbine’s exit tube is shaped to help decelerate the water flow and recover the pressure. Usually the flow velocity (velocity perpendicular to the tangential direction) remains constant throughout, i.e. Vf1=Vf2 and is equal to that at the inlet to the draft tube.