COMPUTATION OF ATTACHED FLOW PAST AN AIRFOIL PROFILE AT HIGH REYNOLDS-NUMBERS

A mathematical model of an attached flow of an incompressible fluid past an airfoil profile at high Reynolds numbers is proposed. The model enables one to determine the effect of viscosity on the magnitude of aerodynamic characteristics. Not only is the displacing action of the turbulent boundary layer and wake on the external flow taken into account, but the solution in the neighbourhood of the trailing edge is also studied, and this makes it possible to formulate a more accurate analogue of the Chaplygin-Zhukovskii condition. Comparison of numerical results with experimental data shows that the accuracy of the results is comparable with that of experiment. The flow past a profile is usually computed by solving a sequence of problems arising when the concept of the Prandtl boundary layer is applied regularly. In this approach the external problems describe the flow of an inviscid fluid past modifications of the profile, which take into account the displacement of the boundary layer and distortion of the wake. Their unique solution satisfies the additional demand of regularity. To a first approximation such a demand is represented by the Chaplygin-Zhukovskii condition. To a second approximation the condition is obtained by analysing the solution of the Navier-Stokes equations near the trailing edge of the profile. In the present paper the analysis is carried out for a profile with a sharp trailing edge, in which the angle between the tangents is not zero.