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-   -   Lift generated by rotation (https://www.askmehelpdesk.com/showthread.php?t=11695)

  • Aug 10, 2005, 08:32 AM
    Whuffle
    Lift generated by rotation
    Hi,

    Can anyone tell me how to calculate the lift caused by rotation of a cylinder in a flow of air?

    We could define the cylinder as being 14ft long, 6ft wide and rotating at 10,000rpm

    Airflow could be anything above 10mph
  • Jul 27, 2007, 03:46 PM
    Stratmando
    Is it dimpled like a golf ball or polished smooth?
  • Jul 27, 2007, 03:50 PM
    Capuchin
    Wow, 2 year old post, start, how did you pick up on this one? :)

    I see no reason why the cylinder shoul dbe dimpled.
  • Jul 27, 2007, 04:15 PM
    Stratmando
    In 2 years, no one answered, I was curious. Thinking the surface would have an effect.
    Hope all is well.
  • Jul 27, 2007, 04:19 PM
    Capuchin
    Yes, it does, but we can assume it's smooth, no? :)
  • Jul 27, 2007, 04:28 PM
    Capuchin
    Check out Magnus effect - Wikipedia, the free encyclopedia

    The dimples of a golfball help to enhance this effect. But it still happens for a smooth surface (for exampl, bullets).
  • Jul 27, 2007, 04:40 PM
    Stratmando
    The shadowraph of 308 winchester, looks exactly like a boat and its wake.
    Poster if your out there, here is what you have been waiting for, I hope, Sorry about the wait.
    [edit] Example Equation
    The following equations demonstrate the manipulation of characteristics needed to determine the lift force generated by inducing a mechanical rotation on a ball.


    F = lift force
    ρ = density of the fluid
    V = velocity of the ball
    A = crossectional area of ball
    Cl = lift coefficient
    The lift coefficient is very dependent on the spin ratio ( (angular velocity*diameter)/(2* linear velocity) ) of the ball. Lift coefficient may be determined from graphs of experimental data using Reynolds number and spin ratio. Typical lift coefficients of a smooth ball range from 0.2 to 0.6 for spin ratios ranging from 0.5 to 4.5.

    Is that a wing for an Experimental Aircraft, or you can't tell?
  • Jul 27, 2007, 04:50 PM
    Capuchin
    Strat, I already gave the link the article containing the exact text, why copy paste it while forgetting to copy paste the equation? :rolleyes:

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