Research on Brownout Characteristics of Helicopter Approach Flight Based on the Unsteady Momentum Source Model Coupled with DEM

다국어 초록 (Multilingual Abstract)

In order to numerically simulate the brownout phenomenon encountered by helicopters in a sandy environment, a new coupled method is established that takes into account the accuracy and efficiency of calculation. In this method, the computational fluid dynamics (CFD) method based on the unsteady momentum source model and the discrete-element method (DEM) based on discrete dynamics are coupled to deal with this two-phase flow problem. In order to verify the validity of the calculation method, the results were compared with available real aircraft brownout flight test results, the results of the RANS method based on overset grids, and the results of the viscous vortex particle method (VVPM). Then, by applying the established method, a numerical simulation of the brownout phenomenon of a typical helicopter approach maneuver was carried out. The results show that after maneuvering descent changes into near-ground forward flight, the sand cloud that is generated is widely distributed and has a lower concentration near the fuselage, and the overall particle saltation characteristics are similar to those at higher forward flight speeds. This means that the phenomenon of brownout is reduced for a certain period of time in the approach chosen in this paper.