The Measurement and Comparison of the Unsteady Aerodynamic Characteristics of a Delta Wing in the Lateral Motions

Abstract

It requests the advanced high agile combat aircrafts to have the abilities to do post-stall maneuvers today. And it is meaningful for the design of aircraft and the control law to investigate the unsteady aerodynamic characteristics of the aircraft during the maneuvers. The present work shows some wind tunnel experiment results of the unsteady aerodynamic characteristic of a delta-wing model in the lateral motions, which were roll oscillation, yaw oscillation and coupled motion( rollyaw motion), at Nanjing University of Aeronautics and Astronautics (NUAA for short). The lateral maneuvers were simulated by a two-degree-offreedom forced oscillation test rig and the unsteady force and pressure of the model were measured in the tests also including the dynamic PIV measurement. The moment results show the hysteresis in the roll and yaw oscillation apparently but not in the coupled motion. The further results of the dynamic pressure and PIV measurements show the structure of the flow field and explain the reasons of the hysteresis of the moment in the roll and yaw oscillation, which is the development of the leading edge vortexes during the oscillations. While either the results of the pressure or the PIV seem to be quasi-steady in the coupled motion. It is much clearer about the unsteady aerodynamic characteristics of the delta wing and it is meaningful to explain the reasons of the hysteresis during the maneuvers for the delta wing.