NUMERICAL INVESTIGATION ON AERODYNAMIC PERFORMANCE OF HOVERING ROTOR IN GROUND EFFECT

As the helicopter hovers near the ground, the interactions among the rotor, the wake, and the ground complicate the flow field, altering the rotor’s aerodynamic forces significantly. To investigate the influence of ground effect on the rotor aerodynamic characteristics, the flow around the rotor in hover is numerically simulated by using the in-house Computational Fluid Dynamics (CFD) codes with a structured dynamic overset grid system. A novel 5th-order WENO-K scheme based on nonlinear reconfiguration is employed for spatial discretization, effectively reducing the numerical dissipation and achieving high-accuracy capture of the tip vortices. In this study, the aerodynamic forces and flow fields of the S-76 rotor in ground effect and out ground effect are compared. The influence and mechanisms of ground effect on rotor aerodynamic characteristics are analyzed in detail. Results show that the ground effect causes a strong upwash flow in the inboard region of the blade and compresses the tip vortices, result in a significant increase in thrust at the blade root and a slight decrease in thrust at the blade tip, respectively.