Numerical simulation of rotor-airframe aerodynamics using technology of unstructured overset grids

The simulation of the complicated unsteady flow around a rotor-airframe configuration is made by numerically solving 3-D Euler equations based on unstructured dynamic overset grids. For the effective treatment of the flow field involving relative motion between the rotor and the airframe, the computing domain is decomposed into two overlapping subzones, namely, a rotational subzone containing the rotating rotor blades and a stationary subzone containing the airframe. The overlapping area of two subzones is used to couple the flow variables of the two zones. The Taylor series expansion is used to obtain second-order spatial accuracy, and dual-time stepping was adopted to improve the solution accuracy. Validation is made by numerically simulating the flows around the Georgia Tech rotor-airframe configuration and comparing the predicted time-averaged and instantaneous inflow and airframe surface pressure distributions with experimental data. It is shown that the present method is efficient and robust for the prediction of complicated unsteady rotor-airframe aerodynamic interaction phenomena.