Euler calculation of rotor-airframe interaction based on unstructured overset grids

The rotor-airframe unsteady interaction aerodynamic, simulated by solving the three-dimensional unsteady Euler equations based on the unstructured overset grids was investigated. The method of unstructured mesh could easily handle the complex geometries, and the overset grids could treat the relative motion of helicopter rotor-airframe interaction effectively by dividing the flowfield into two overset subzones. The dual-time-stepping method was adopted to advance the time-accuracy solution. The mean pressure distribution was obtained by averaging the instantaneous pressure over a complete cycle of revolution of the rotor. The effect of the blade passage was well predicted, with a high pressure rise at the nose region of the airframe at zero blade azimuth angles. The formation of the trailing tip vortex, its migration to the downstream of the rotor, and the impingement of the tip vortex on the fuselage were observed in the resultant figure.