Numerical simulation of helicopter aeromechanics in slow descent flight

Abstract

In this paper we present numerical simulation results for a generic helicopter configuration in slow descent flight. The well known HART-II test case has been chosen as the experimental reference, especially the baseline case. This test case is characterized by the occurrence of Blade-Vortex Interactions (BVI) and can thus be considered as very ambitious with respect to the aerodynamic simulation. The HART-II test case has been subject to previous investigations at the Institute. A local mesh refinement technique using tube-shaped vortex-adapted Chimera grids was developed in order to improve the vortex conservation in the numerical simulation and thus to allow for the quantitative reproduction of BVI induced airloads. In contrast to earlier results, the vortex grids are extended to fill the entire rotor disk and the trim including the fuselage is run to convergence. A comparison of the numerical simulations with wind tunnel experiments shows the improvement in the prediction of the aeromechanics of the helicopter. The numerical simulations incorporating the enhancements mentioned above were run on the vector computer NEC SX-8 located at the high performance computing center Stuttgart.