100 thoughts on “Working of Francis Turbine

  1. great, very helpful !! can you make a vido explaining the design of the blades of a compressor wheel please ?

  2. I'm not sure if it was better hearing a computer voice written by an indian, or hearing an indian do it wrong. ffs

  3. we have blades in the turbine rotor/impeller and so why do we need guide vanes. stay vanes are more sufficient isnt it??, to direct the water towards eye of the impeller

  4. I'm a bit confused, even if there was a low pressure on the exit of the turbine, where would cavitation form? Cavitation occurs when at a low pressure, bubbles of gas form, and then when exposed to an increment in pressure the bubbles implode and that is when you have trouble, right? It makes no sense to me to increase the pressure in the exit to "avoid cavitation"

  5. Francis turbines are the most preferred hydraulic turbines. It contributes about 60% of the global hydro power capacity mainly because it can work efficiently under wide range of operation conditions. The most important part of a Francis turbine is its runner. It is fitted with complex shade blades. In the runner, water enters radially and exits axially. During the course of flow, water goes through the runner blades. Francis turbine blades are specially shaped. We can note that blades are having thin airfoil cross section. So, when water flows over it, low pressure will be produced on one site and high pressure in the other site. This will result in a lift force. We can also note one more peculiar thing about the blade. It is having a bucket kind of shape towards the outlet. So, water will hit, and producing impulse force before leaving the runner. Both impulse force and lift force will make the runner rotate. So Francis turbine is not a pure reaction turbine. A portion of force come impulse action also. Thus, when water flows over runner blades, both its kinetic and pressure energy will come down. Since flow is entering radially and leaving axially, they are also called mixed flow turbine. Runner is connected to the generator via shaft for electricity production. This arrangement is fitted in a spiral casing. Flow enters via inlet nozzle. Flow rate of water will get reduced along length of casing, since water is drown into the runner. But decreasing area of spiral casing will make sure that water flow is entered to runner region almost at uniform velocity. Stay vanes and guide vanes are fitted at the entrance of runner. The basic purpose of them is to convert one part of pressure energy to kinetic energy. Flow which is coming from the casing meets stay vanes, they are fixed. Stay vanes steers the flow towards runner section. Thus, it reduces inlet flow. Demand for power changes over time. The guide vane mechanism is used to control flow rate and make sure that power production is synchronized with power demand. Apart from controlling flow rate, guide vanes also control flow angle to inlet portion of runner blade. Thus, guide vanes make sure inlet flow angle is the optimum angle of attack for maximum power extraction from fluid. Low pressure at the outlet of the turbine may cause serious problems of cavitation. So, a special draft tube is designed is fitted at exit site to discharge the fluid out. Draft tube will transform velocity head to static head due its increasing area that will reduce effect of cavitation.

  6. No.

    Some popular science explanation is need..

    The draft tube gradually widens in area and slows the fluid down before it exits. Slower speed means something has to hold the horses back and the only way that could happen is a pressure gradient. Each tiny flow element will have to feel an external net force reducing its speed.

    The only way to have a net force that affects speed is to feel more pressure on your face than on your back. As the first guy exiting the draft tube enters free air with his "face pressure" only defined by the water depth of exit, the gradual pressure forces will pile up like in a battery stack and you will have the minus pole of the pressure gradient sum at the inlet of the draft tube.

    So the draft tube is a pressure battery stack driven by kinetic energy and introduces much wanted reduced pressure at the turbine exit. A side effect is any factor of cavitation will increase.

    If the design is subject to cavitation you can add static pressure to the turbine by placing it as low as practically possible, sometimes located far below the water level of the exit.

  7. The problem is that what so called Guide Vanes will also reduces the velocity of the flow due to the friction and change in the direction of the flow. So the gain in energy relating to that could be small or nothing.

  8. Man, can you imagine being the native English speaker who was forced to read this shitty google translate script? He probably was told if he didn’t read the shit Chinese or whatever translation, he wouldn’t be hired.

  9. very helpfuuuul thank youuuuuuuu❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️

  10. I just want to say that I find the dropped articles very annoying. For instance, you say "thus it reduces [the] swirl of [the] inlet flow" without the bracketed the's. Excellent video though!

  11. As a hydro power engineer your video was very useful for me. Because my first project was a vertical Francis turbine.

  12. Lift force with no compressible fluid? Is that correct?
    I tought it was just impulse force
    Is lift force really relevant against impulse force?
    Could anyone tell the % of each one?

  13. Thanks . Now I now how it works .I see some improvements can be made . But for now in 2019 it will be fine .

  14. This channel is amazing! Keep up the good work! Very helpful for learning about other engineering topics, as a materials engineer

  15. I was wondering if you could use big enough turbine to with hydraulic fluid to power something like lawn mower XD. Might sound stupid, but why not? And if needed there could be torque converter too. because if it would work, there could be small engine spinning pump that would move the fluid. That way lawn mowers could have smaller engine than needed.

    edit: Also i forgot that isn't this how some lawn mowers already move?

  16. Isn't the draft tube used to lower the pressure on the downside of the turbine to increase the pressure drop over the runner? From what i've learned the draft tube is actually causing more cavitation but there are ways to counter this.

  17. Super explaination but I need to know in deep and very keen information from point to point how turbine is been prepared and which type of material is been used

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