円形閉/開風洞中の翼の誘導抵抗

抄録

The spanwise lift distribution and induced drag of a wing in a circular wind tunnel, with either closed or open working section, are studied. The exact expressions of the spanwise optimum lift distribution and the minimum induced drag are obtained from the TREFFTZ plane Bow field in either case. In the closed tunnel case, as the ratio of wing span to tunnel diameter increases, the lift distribution changes gradually from elliptic to uniform one, and the induced drag also gradually decreases until it becomes zero. In the open tunnel case, the distortion of the lift distribution caused by the presence of the tunnel boundary is rather small, even when the ratio of wing span to tunnel diameter reaches unity. It is seen that the simple ROSENHEAD type of correction based on the elliptic lift distribution is satisfactory for all practical cases in which the lack of uniformity of the airstream or the size of the airfoil chord does not become excessive.