Study on aerodynamic interference between helicopter hovering rotor and plateau complex terrain

The interference of turbulence induced by valley terrain on helicopter rotors has a profound impact on aerodynamic characteristics and flight safety. In this study, CFD simulations based on the standard k-ω turbulence model were conducted for the pressure-driven atmospheric boundary layer over a plateau valley model with appropriate inlet conditions. The flow fields were coupled with a hovering rotor using the overset mesh method to investigate the aerodynamic interference. Significant acceleration and deceleration phenomena were observed in the valley, and the turbulent kinetic energy diminished gradually with increasing altitude. Typical turbulence characteristics, such as downwind motions, vorticities, and downdrafts, were prevalent in the valley. The upward velocity component of the downwind flow enhanced the rotor's thrust coefficient and hovering efficiency, albeit at the expense of increasing its pitching moment and inducing oscillations. The airflow in the vortex region was disordered, with continuous changes in flow direction, and the aerodynamic forces of hovering rotors at nearby positions varied considerably, indicating potential wind shear. Downdrafts reduced the rotor's thrust coefficient and hovering efficiency, and the high turbulent kinetic energy regions within the downdrafts tended to cause pitching moment oscillations. The research results provide technical support for helicopter flight strategy and safety control in complex terrain environments.