Computation of the Helicopter Fuselage Wake with the SST, SAS, DES and XLES Models

Abstract

Abstract This paper presents a first industrial attempt at Eurocopter Germany to use DESlike methods to compute the wake behind a helicopter in forward flight. Three codes have been used: TAU (DLR), CFX (Ansys) and HMB (Uni. Liverpool) and four different turbulence models: standard SST and three of its unsteady extensions SAS, DES and XLES. Results for the loads, pressure distribution and skin-friction lines have been compared to each other and against wind tunnel experimental data. These more sophisticated models brought improvements over the base SST but not always markedly and consistently: the drag gets improved although the negative lift on the body departs further form the experimental value. The pressure distribution on the backdoor has been improved by one of the computation. Oil-flow visualisation results show that the mean flow in the region of the backdoor is qualitatively reasonably well captured.