AERODYNAMICS AND ACOUSTICS OF ROTOR BLADE-VORTEX INTERACTIONS

As part of an international cooperative program, several aerodynamic a nd acoustic prediction codes have been recently developed to understan d the rotor blade-vortex interaction (BVI) noise. Furthermore, a joint validation activity of these prediction codes was performed with the blade surface pressure and acoustic data taken in the German-Dutch Win d Tunnel with the 1/7-scale model AH-I Operational Loads Survey blades . Careful attention has been given to the detailed flowfield, especial ly wake structures during BVIs including the miss-distance between vor tex and blade, vortex core size, and tip vortex trajectories. The resu lts of flowfield including wake systems from various prediction codes show some quantitative differences, but the acoustic results using the se calculated airloads as inputs compare reasonably well with test dat a.