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    Whuffle's Avatar
    Whuffle Posts: 19, Reputation: 1
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    #1

    Aug 10, 2005, 08:32 AM
    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
    Stratmando's Avatar
    Stratmando Posts: 11,188, Reputation: 508
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    #2

    Jul 27, 2007, 03:46 PM
    Is it dimpled like a golf ball or polished smooth?
    Capuchin's Avatar
    Capuchin Posts: 5,255, Reputation: 656
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    #3

    Jul 27, 2007, 03:50 PM
    Wow, 2 year old post, start, how did you pick up on this one? :)

    I see no reason why the cylinder shoul dbe dimpled.
    Stratmando's Avatar
    Stratmando Posts: 11,188, Reputation: 508
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    #4

    Jul 27, 2007, 04:15 PM
    In 2 years, no one answered, I was curious. Thinking the surface would have an effect.
    Hope all is well.
    Capuchin's Avatar
    Capuchin Posts: 5,255, Reputation: 656
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    #5

    Jul 27, 2007, 04:19 PM
    Yes, it does, but we can assume it's smooth, no? :)
    Capuchin's Avatar
    Capuchin Posts: 5,255, Reputation: 656
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    #6

    Jul 27, 2007, 04:28 PM
    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).
    Stratmando's Avatar
    Stratmando Posts: 11,188, Reputation: 508
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    #7

    Jul 27, 2007, 04:40 PM
    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?
    Capuchin's Avatar
    Capuchin Posts: 5,255, Reputation: 656
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    #8

    Jul 27, 2007, 04:50 PM
    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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