Dynamic Aeroelastic Analysis of Wing/Store Configurations

Limit-cycle oscillation, or LCO, is an aeroelastic phenomenon characterized by limited amplitude, self-sustaining oscillations produced by fluid-structure interactions. In order to study this phenomenon, code was developed to interface a modal structural model with a commercial computational fluid dynamics program. LCO was simulated for a rectangular wing, referred to as the Goland+ wing. It was determined that the aerodynamic nonlinearity responsible for LCO in the Goland+ wing was the combination of strong trailing-edge and lambda shocks which periodically appear and disappear. This mechanism limited the flow of energy into the structure which quenched the growth of the flutter, resulting in a steady LCO. Under-wing and tip stores were added to the Goland+ wing to determine how stores affected limit-cycle oscillation. It was found that aerodynamic store shapes affect LCO in two off-setting ways: under-wing stores interfere with the airflow on the lower surface of the wing which decreases LCO amplitudes, whereas, aerodynamic forces on both under-wing and tip stores directly increase LCO amplitudes