抄録
Relations of aerodynamic sound and vortex motions in a flow separated from a sharp edged fence and from fences with vortex generators were discussed by simultaneous measurements of aerodynamic sound and fluctuating static-pressure, flow visualizations with smoke and velocity measurements. Sound source terms of Ribner's Dilatation theory were calculated with measured fluctuating static-pressure, and integral of coherent output power of the sound source term and results of flow visualizations were discussed to determine flow regions and vortex motions contributing to aerodynamic sound generation. As an additional experiment, vortex generators were attached to the fence to introduce three-dimensional perturbations into the separated shear flow and spectrum of aerodynamic sound and velocity fields in the flow were investigated. The results suggest that aerodynamic sound in relatively high frequency band is increased by small scale vortices near the fence and that in relatively low frequency band is related to large scale vortices which are organized via vortex merging.
