Fast Viscous Correction Method for Unsteady Transonic Flow About Airfoils

This study modified the inviscid, small-disturbance, unsteady, transonic code, LTRAN2, to consider the viscous effect. The boundary condition of the vertical surface velocity needs to include an additional term which is derived from the effective displacement thickness of the boundary layer. The effective thickness consists of a viscous wedge to simulate the suddenly thickened boundary layer behind a shock and a displacement thickness obtained from a conventional integral boundary-layer method. Unsteady aerodynamic performances were calculated for several airfoils. Comparisons were made with experimental data of two supercritical airfoils. The viscous solutions gave better agreement with experimental data with practically no increase in computational time