关键词: 旋翼流场, 地面效应, 非结构网格, 嵌套网格, 计算流体力学, 直升机

Abstract: A computational fluid dynamics (CFD) solver based on the unstructured embedded grid technique is developed aiming at simulating the flowfield of a rotor in ground effect (IGE) and analyzing the effect of the ground on rotor aerodynamic characteristics with accuracy. In this solver, the three-dimensional unsteady N-S equations are discretized by a second-order upwind finite-volume scheme and one surface of the background embedded mesh is used to simulate the effect of the ground. By the model developed, the rotor flowfield in the out of ground effect (OGE) condition is first simulated and the calculated results are compared with available experimental data for validation. Then, the location of the bladetip vortex and the rotor thrust increment in the IGE condition are calculated, and the flowfield characteristics and the development of the ground vortex in lowspeed forward flight in the IGE condition are also simulated. Based upon the above simulation results, some meaningful conclusions are drawn.

Key words: rotor flowfield, ground effect, unstructured mesh, embedded grid, computational fluid dynamics, helicopter