How does francis turbine work

To know more about the author check this link. Ltd All Rights Reserved. How does Francis Turbine work? A detailed webpage version of the video is given below. Overview of working of francis turbine Water head and flow rate are the most vital input parameters that govern performance of a hydraulic turbine. Runner — At the heart of the system Most important part of Francis turbine is its runner. Fig: 2 Water flow through francis turbine runner Blades of Francis turbine are specially shaped. Fig: 3 Airfoil cross section shape of francis blades and production of reaction force You can also note one more peculiar thing about the blade.

Fig: 4 Francis turbine derive energy from combined action of reaction and impulse force So Francis turbine is not a pure reaction turbine, a portion of force comes from impulse action also. Use of spiral casing Runner is fitted, inside a spiral casing. Fig: 5 Spiral casing makes sure that flow is entered uniformly along the periphery of runnner Stay vanes and guide vanes are fitted at entrance of runner.

Fig: 6 Stay vanes and guide vanes used in Francis turbine Flow which is coming from the casing, meets stay vanes, they are fixed. Governing of francis turbine Demand for power may vary over time. Fig: 7 First figure shows guide vanes in closed position; In 2nd figure guide vanes in open position Apart from controlling flow rate guide vanes also control flow angle to inlet portion of runner blade.

Living with cavitation Most often local pressure at exit side of runner goes below vapor pressure of water. Figure 3. A three dimensional model of a Francis turbine. Fossil Fuels. Nuclear Fuels. Acid Rain. Climate Change. Climate Feedback. Ocean Acidification. Rising Sea Level. Francis turbine. The chances of eddy formation and pressure loss are reduced as the area of flow becomes gradually convergent.

The runaway speed of the turbine is automatically checked as the centrifugal force acts outwards while the flow is inward. The guide vanes can be located on the outer periphery of the runner, therefore, better regulation is possible. The frictional losses are less as the water velocity over the vanes is reduced.

The inward flow turbine can be used for fairly high heads without increasing the speed of the turbine as the centrifugal head supports a considerable part of the supply head. The velocity triangle at inlet and outlet of the Francis turbine is drawn in the same way as in case of inward flow creation turbine. Vw2 will be zero.

Hence velocity diagram for Francis turbine is shown below. Flow ratio varies from 0. Speed ratio varies between 0. Specific speed Ns : of a turbine is defined as the speed of a geometrically turbine which would develop unit power when working under a unit head. The formation, growth, and collapse of vapor filled cavities or a bubble in a flowing liquid due to local fall in fluid pressure is called cavitation.

The value of critical factor depends upon specific speed of the turbine. Hydraulic efficiency :. It is defined as the ratio of the power produced by the turbine runner and the power supplied by the water at the turbine inlet.

Volumetric efficiency :. Mechanical efficiency :. The power produced by the runner is always greater than the power available at the turbine shaft. This is due to mechanical losses at the bearings, windage losses and other frictional losses. Overall efficiency :. This is the ratio of power output at the shaft and power input by the water at the turbine inlet.

Fluid Mechanics - Notes , articles , Interview Que. Currently, he is working in the sheet metal industry as a designer. Additionally, he has interested in Product Design, Animation, and Project design. He also likes to write articles related to the mechanical engineering field and tries to motivate other mechanical engineering students by his innovative project ideas, design, models and videos.

Hi How are you I am Najeeb from Kerala India I have a project hydro power production from a large over head tank carrying around cbm water silo shaped steel structure stand 30 to 40 meters head. Works Francis turbine generat power. I think it will get necessary pressure because the whole weight ton apply downward. My technologies the discharged water to bring the over head tank. The working principle, main components and its application is discussed in this article.

Fig 1: Components of Francis Turbine. Contents: Main Components of Francis Turbine 1. Spiral Casing 2. Stay Vanes 3. Guide Vanes 4. Runner Blades 5. Applications of Francis Turbine.