Kaplan Turbine Working and Design

Kaplan turbines are suitable for power extraction when water energy is available at low head and high flow rate which means they are suitable for operation when water is stored in big reservoir at relatively shallow altitude In kaplan turbine flow is entered through a spiral casing decreasing area of casing make sure that flow is entered through center portion almost at uniform velocity
throughut the perimeter water after crossing the guide vanes passes over the runner finally it leaves through the draft tube most important part of kaplan turbine is it’s runner cross section of runner blade will have a curve shape when water flows over it it will induce a lift force due to airfoil effect tangential component of lift force will make the runner rotate this rotation is transferred to a generator for electricity production kaplan turbines are axial flow machines where absolute velocity of flow is parallel to axis of turbine water is precisely meet to pass through the runner blades with the help of shroud power demand may fluctuate over time this can meet for varing power demand blades of kaplan turbine are designed to operate under wide range of operating conditions A rotating blade experiences relative velocity of flow the fundamental thing in blade design is relative velocity of fluid flow should be at optimum angle of attack at all cross sections even though absolute velocity is axial relative velocity will be inclined depending upon blade velocity Inclination of relative velocity increases as removed from rotor tip there should be continuous twist in blade from rotor tip so that at every cross section the angle of attack is optimum with varing flow condition relative velocity will change drastically kaplan turbine blades are adjustable when flow rate is high relative velocity of flow will be more axial so blades should pitch vertically If flow rate is low relative velocity of flow is more tangential So blades are pitched in tangential direction in short the pitching action of blade make sure that blade is still in optimum angle of attack even under varying flow apart from controlling the flow rate guide vanes have got one more function they help in controlling swirl of flow if guide vanes will not present the flow would be highly swirling in nature such a flow will reduce performance of turbine drastically due to its poor angle of attack so guide vanes control swirling flow for optimum angle of attack biggest challenge in design of kaplan turbine is how to overcome problem of cavitation which causes material erosion and vibration cavitation is unavoidable in kaplan turbine since in most of the regions pressure goes very low but damage due to cavitation can be reduced by using suitable draft tube which transforms dynamic pressure to static pressure

100 thoughts on “Kaplan Turbine Working and Design

  1. Very informative video, thank you. I'd like to know, if you were given a site that have low head and small flow rate, what type of turbine would you use? (besides waterwheel)

  2. To : @Learn Engineering 
    I hope you will explain about , Cross Flow Turbine , Turgo Impluse Turbine, tubular turbine dan bulb turbine. with your awesome animation 3d like have you upload.

  3. Good job
    I have a case study in river without dam ( conjunction ) h=6.5 m, Q=(45 to 86) cubic metres
    what is the best type of turbine used?

  4. I'm thinking of using a jet ski pump drive, should I introduce the water flow thru the original intake? because the impeller blades pitch is reduced going towards the output, what do you think sir

  5. Very nice presentation , I want to have a similar video on turbine Governing which is a complicated subject.

  6. Aw, this was a really nice post. In idea I wish to put in writing like this moreover – taking time and precise effort to make an excellent video however what can I say I procrastinate alot and under no circumstances appear to get something done.

  7. Well, this isn't a great description how a Kaplan turbine works. The guide vanes for example, are newer pointing to the center, and the main reason with the adjustable blade is to have optimized trailing edge angle so the flow swirl component from the guide vanes are fully absorbed by the turbine.

    Half of the static head is converted to velocity when it passes the wicket gate (guide vane assembly) so the water rotates (swirl) when it enters the turbine, this swirl (contains half of the energy) is absorbed and the flow is leaving the turbine in axial direction.

    The swirl angle changes with the flow rate, so with fixed blade the turbine has a narrow band of best efficiency.

    So the main different between a Francis and a Kaplan is that the Kaplan has a much wider range of best efficiency owing the ability to adjust its blades and thus absorb the swirl, so 50% of head is converted to rotation that the turbine absorb and discharge axial, into the draft tube.

    When a Francis turbine operates at full load (BEP is usually 80% of full load) the swirl after the turbine is rotating the opposite direction and therefore the efficiency goes down.

    I'm an hydropower engineer and have worked many years designing Kaplan turbines at Andritz Hydro.

  8. I'm VERY interested in this topic and am moving to areas with high volume/low head….. BUT I can't stand the robotic computer voice. I'll look for the information elsewhere and I'm blocking this channel.

  9. why we need water at inlet of vanes to be of uniform velocity ?. I know this is the function of spiral casing but if the water strikes the vanes with different velocity the turbine will still work . How will this affect the efficiency ?

  10. Great explanation. But, artificial voice makes irritating. Please edit the dubbing of video with human being voice. If you need assistance , I'd help.

  11. Can someone please explain to me what is the use of the swirl casing for Kaplan turbine. If the end requirements for water entering the runner are to be axial and uniform throughout the perimeter, we can simply put the runner in the pipe from which water is entering the swirl casing. It would reduce pressure loss as well.

  12. I have a doubt here. So, when water comes out from the draft tube into the open atmosphere, what makes sure that the pressure have come down to atmospheric level?? It it the length of the tube or the cross section ? if so then again there is more doubt. The flow rate and flow velocity is variable. If for a certain design, what happens if water enters at high speed (higher than the design speed).

  13. The blades are curved incorrectly for downward flow of water. The way they are shown will not result in lift, only reaction.

  14. Какую чушь несёт этот " физик – механик", но умно так, даже с векторами. Нихрена в турбинах не смыслящий. Турбина в другую сторону крутится, вместе с потоком, который закручивает спиральная камера. А крутящий момент на турбине образуется от разницы давления сверху и снизу лопасти, как у самолёта. Физик – недоучка "механику" прочитал, до гидравлика не добрался.



  16. Where is this rotating turbine to bring us freedoms from the police state and things citizens used to do freely but can't because of fear of them? Just because you don't see it doesn't mean it isn't there. Even in a deep police state there are still loopholes to allow you to shift things in your favor so it seems like your doing something illegal but really aren't. Look at the loopholes in 1984. As secured as their society was it was able to be exploited eventually.

  17. Sir, I have been searching for a youtube channel which will describe the complex functions and geometry of complex machines. Your channel gave me all these information within a short time. Thank you very much. Keep making these kind of videos. God bless you. Love your work.

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