Steady characteristics of an aerofoil section in a subsonic shear flow.

Abstract

Steady characteristics of an aerofoil in a two-dimensional supersonic shear flow are analyzed by the singularity method. First, on the assumption of small disturbances, a fundamental solution, which represents a supersonic source, is introduced from an equation for perturbed pressures. The solution is composed of two terms; one contains the same Dirac's delta function as in a uniform supersonic flow and the other represents the interference between a source and vorticities in a shear flow. The thin aerofoil theory is applied in order to analyze characteristics of an aerofoil having a thickness distribution. The strength of sources at a point on an upper or lower surface of the aerofoil is determined not only by the gradient of the shape of the aerofoil but also by the interference between sources distributed on the upstream part of the surface from the point and vorticities in a shear flow. In a shear layer, a jet and a wake, lift and drag forces acting on a lens aerofoil and a flat plate are calculated. The results show that a local vorticity at a flat plate are calculated. The results show that a local vorticity at a position of an aerofoil plays an important role for characteristics of the aerofoil.