Accelerated method of helicopter brownout with particle-particle collisions

Abstract

A novel background mapping-splitting method is proposed and coupled with an analysis method of helicopter brownout based on a viscous vortex particle method and a discrete element method to improve the efficiency of brownout simulations. In this work, particle-particle collisions are considered and a background mapping method where sand particles are mapped into structured background grids is established to accelerate the simulation. Furthermore, a background splitting method where a structured background grid is divided into several zones is developed to reaccelerate the simulation. The method is then demonstrated for the US Army EH-60L in brownout. The results show that the predicted behavior of brownout agrees well with observations from flight tests of the EH-60L. The CPU time of a direct method in the brownout simulation increases as a parabola, while the CPU time of the present method is a linear growth. Compared with the direct method, the efficiency of the present method is significantly improved, and the computational time is reduced by 70.29% compared with the background mapping method for a 10 million particles case.