Lift interference effects are discussed based on Bland's integral equation. A mathematical existence theory is utilized for which convergence of the numerical method has been proved for general (square-integrable) downwashes. Airloads are computed using orthogonal airfoil polynomial pairs in conjunction with a collocation method which is numerically equivalent to Galerkin's method and complex least squares. Convergence exhibits exponentially decreasing error with the number n of collocation points for smooth downwashes, whereas errors are proportional to 1/n for discontinuous downwashes. The latter is reduced to 1/nm+1 with mth order extrapolation to the limit (using m = 2 we obtain hundredfold error reductions with only a 13 % increase of computer time). Numerical results are presented showing acoustic resonance, and the effect of Mach number, ventilation, height to chord ratio, and mode shape on wind tunnel interference. Excellent agreement with experiment is obtained in steady flow, and good agreement is obtained for unsteady flow. (DePo)


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    Title :

    Aerodynamic interference effects on oscillating airfoils with controls in ventilated wind tunnels


    Additional title:

    Aerodynamische Interferenzwirkung auf oszillierende Tragfluegel-Messungen im Windkanal


    Contributors:

    Published in:

    AIAA Journal ; 18 , 4 ; 417-426


    Publication date :

    1980


    Size :

    10 Seiten, 10 Bilder, 3 Tabellen, 36 Quellen



    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English