Evaluation of Aerodynamic Characteristics in Oscillatory Coning Using CFD Methods

Abstract

The wind tunnel rotary-balance testing is widely used in aircraft dynamics to characterise aerodynamics at moderate and high angles of attack during stall and spin regimes. In such experiments an aircraft test model is rotated along the wind-tunnel free-stream velocity vector allowing the measurement of aerodynamic characteristics in steady rotational flow conditions with constant angle of attack and sideslip. In modified tests named as oscillatory coning, the rotation vector is tilted from the free-stream velocity vector making flow conditions with periodic variations in angle of attack and sideslip. This allows evaluation of unsteady aerodynamic responses superimposed on steady conical rotation. The use of CFD methods for prediction of aerodynamic characteristics in rotary-balance and oscillatory coning conditions may significantly complement experimental data via extrapolation of data for higher Reynolds numbers, elimination of interference effects from supporting system, extraction of unsteady aerodynamic derivatives affecting aircraft dynamic stability. This paper presents CFD simulation results obtained in rotary-balance and oscillatory coning motions for the NASA Common Research Model (CRM) in its wing-body configuration at moderate $Re=1\times10^6$, low Mach number $M\mbox{=}0.2$ and the use of the obtained unsteady responses in aerodynamic modelling.