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Francis inlet scroll at the Grand Coulee Dam Side-view cutaway of a vertical Francis turbine. Here water enters horizontally in a spiral-shaped pipe (spiral case) wrapped around the outside of the turbine's rotating runner and exits vertically down through the center of the turbine. The Francis turbine is a type of water turbine.
In this turbine, the working fluid enters around the axis of the wheel and then flows outwards (i.e., towards the outer periphery of the wheel). The guide vane mechanism is typically surrounded by the runner/turbine. In this turbine, the inner diameter of the runner is the inlet and outer diameter is an outlet. [1]
A wicket gate, or guide vane, is a ring of gates (or vanes) surrounding a water turbine which control the flow of water entering it; varying the aperture between them manages the rate of the turbine's spin, and thereby the amount of electricity generated.
Turbines are sometimes differentiated on the basis of the type of inlet flow, whether the inlet velocity is in axial direction, radial direction or a combination of both. . The Francis turbine is a mixed hydraulic turbine (the inlet velocity has Radial and tangential components) while the Kaplan turbine is an axial hydraulic turbine (the inlet velocity has only axial velocity componen
Turbine inlet guide vanes of a turbojet. Velocity triangles can be used to calculate the basic performance of a turbine stage. Gas exits the stationary turbine nozzle guide vanes at absolute velocity V a1. The rotor rotates at velocity U. Relative to the rotor, the velocity of the gas as it impinges on the rotor entrance is V r1.
The two engineers worked on improving the turbine. And in 1848, Francis and Boyden successfully improved the turbine with what is now known as the Francis turbine. Francis's turbine eclipsed the Boyden turbine in power by 90%. In 1855, Francis published these findings in the "Lowell Hydraulic Experiments". [8]
The guide vanes should seal to the edges of the turbine casing so that when the water is low, they can shut off the water supply. The guide vanes therefore act as the valves between the penstock and turbine. Both guide vanes can be set by control levers, to which an automatic or manual control may be connected.
This page was last edited on 29 January 2012, at 10:45 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike License 4.0; additional terms may apply.