Euler calculations for flowfield of a helicopter rotor in hover

Abstract

Aerodynamic loads on a multibladed helicopter rotor in hovering flight are calculated by solving the threedimensional Euler equations in a rotating coordinate system on body-conforming curvilinear grids around the blades. Euler equations are recast in the absolute flow variables so that the absolute flow in the far field is uniform but the relative flow is nonuniform. Equations are solved for the absolute flow variables employing Jameson's finite-volume explicit Runge-Kutta time-stepping scheme. Rotor-wake effects are modeled in the form of a correction applied to the geometric angle of attack along the blades. This correction is obtained by computing the local induced downwash with a free-wake analysis program. The calculations are performed on a CRAY X/MP-48 for a model helicopter rotor in hover at various collective pitch angles. The results compared with experimental data.