FLOWFIELD OF A LIFTING ROTOR IN HOVER - A NAVIER-STOKES SIMULATION

The viscous, three-dimensional flowfield of a helicopter rotor in hover is calculated by using an implicit, upwind, finite difference numerical method for the solution of thin-layer Navier-Stokes equations. The induced effects of the wake, including the interaction of tip vortices with successive blades, are calculated as a part of the overall flowfield solution without specifying any wake models. Comparison of the numerical results at subsonic and transonic flow conditions show good agreement with the experimental data for the surface pressures and the nearfield vortex trajectory. However, the captured vortex structure is diffused due to the coarse grids, but this appears to have minimal influence on the prediction of surface pressures. The paper also presents limited comparisons of the Navier-Stokes results with Euler results along with some discussion on grid refinement studies.