EVALUATION OF A NAVIER-STOKES ANALYSIS METHOD FOR HOVER PERFORMANCE PREDICTION

The TURNS Navier-Stokes analysis was applied in hover to the Black Haw k and 3-to-1 tapered-tip model rotors to evaluate its ability for hove r performance prediction, This analysis utilizes a low-dissipative thi rd-order accurate upwinded scheme and a blade-to-blade periodic grid t o capture the rotor wake, Calculations were made for two rotors over a wide range of thrust coefficients, The elastic twist and coning measu red by experiment were included in the model, Comparisons with experim ental torque and Figure of Merit were made, and the flowfield was exam ined in detail, The correlation with experimental Figure of Merit, usi ng meshes with 380,000 to 950,000 grid points, was considered to be fa ir for design purposes, The discrepancies with experimental performanc e data are believed to be due to an inaccurate prediction of the tip-v ortex position and strength, resulting in poor loading predictions ove r the outer span of the blade, The finest grid calculations improved t he results, indicating that the results may be improved by more grid r efinement and improved meshing, Continued research in the area of grid adaptation and higher-order schemes is necessary to improve the resol ution of the tip vortex for the hovering rotor.