Numerical Research on the Unsteady Evolution Characteristics of Blade Tip Vortex for Helicopter Rotor in Forward Flight

Abstract

A high-resolution numerical method is developed to simulate the generation and evolution progress of the blade tip vortex for helicopter rotor in forward flight. In the current method, the Navier–Stokes equation is adopted as the governing equation. Along with fifth order WENO scheme, the upwind Roe scheme is employed for the calculation of convective flux. A dual time-stepping scheme is utilized for time discretization, and the LU-SGS scheme is used for every pseudo time step. The Spalart–Allmaras model is selected as the turbulence model. To trim the rotor in forward flight, a high-efficiency trim method is introduced to the current solver. Results for cases in different forward flight conditions show that trimming process has a great influence on the evolution characteristics of the rotor tip vortex. Compared with the cases with different Mach numbers, the evolution characteristics of rotor tip vortex have larger difference for cases with different advance ratios.