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 polynominal 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 discontinous downwashes. The latter can be reduced to 1/n(exp(m+1)) with mth order Richardson extrapolation (using m=2 we obtain hundred fold 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 wird tunnel interference. Excellent agreement with experiment is obtained in steady flow, and good agreement is obtained for unsteady flow. (Kursetz)


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    Title :

    Computation of aerodynamic interference effects on oscillating airfoils with controls in ventilated subsonic wind tunnels


    Additional title:

    Vergleich der aerodynamischen Interferenzeinfluesse auf schwingende Tragfluegel mit Kontrolleinrichtung in durchluefteten subsonischen Windtunnels


    Contributors:

    Published in:

    AIAA-Papers ; Jan ; 1-13


    Publication date :

    1979


    Size :

    13 Seiten, 11 Bilder, 4 Tabellen, 37 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English