Anatomy of Turbulence Effects on the Aerodynamics of an Oscillating Prism

Turbulence-induced changes in aerodynamic force characteristics on an oscillating rectangular prism were investigated in this study. It encompassed examination of aeroelastic quantities, i.e., flutter derivatives, and the buffeting components of the integral forces. A forced-vibration system was employed to extract the aerodynamic characteristics of an oscillating prism using a model instrumented with multiple pressure transducers for synchronous scanning of the pressure field. Chordwise distributions of self-excited pressure amplitudes were measured and associated phases were derived to examine the anatomy of turbulence effects on the aerodynamics of the prism rather than simply discern the influence of turbulence on the integrated forces. The resulting changes in flutter derivatives were traced back to a turbulence-induced upstream shifting of the regions of maximum pressure amplitudes. This upstream shifting was consistent with earlier research showing that turbulence increases the radius of curvature of separated shear layers and moves reattachment upstream. In this study, turbulence was found to have a stabilizing effect on the aerodynamics of the prism. The broad band character of the buffeting forces was found to be quite similar to that of stationary prisms with body motion slightly increasing energy content.