Computational fluid dynamics analysis of multi-element, high-lift aerofoil sections at transonic manoeuvre conditions

Abstract

The application of a previously developed computational method to the prediction of high-lift performance for multi-element aerofoil sections operating at transonic flow conditions is described. The flows are computed by solving the Reynolds-averaged Navier–Stokes equations, using a full differential Reynolds-stress turbulence model to evaluate the various Reynolds-stress components appearing in the governing mean-flow equations. Algebraic wall functions are used to bridge the molecular viscosity-dominated region immediately adjacent to the aerofoil surfaces. An unstructured grid-based computational fluid dynamics (CFD) methodology is used to deal with the geometric complexity of the multi-element aerofoil configurations. Initial results are presented for the viscous, transonic flow development around the SKF 1.1 supercritical aerofoil section, equipped with either a trailing-edge flap or a leading-edge slat. Predicted surface pressure distributions generally compare well with experimental data for the two high-lift aerofoil geometries considered, at a free-stream Mach number of 0.6 and over a range of incidence angles. There are some discrepancies in the regions immediately downstream of shock wave/boundary layer interactions, possibly resulting from the use of wall-function boundary conditions in the computations. Predicted Mach number contours indicate the complexity of the transonic flow fields for high-lift configurations, with the slat wake passing through an extensive supersonic-flow region, terminated by a normal shock wave, on the main aerofoil upper surface, for example.