ACOUSTIC INTERACTION WITH VORTEX STRUCTURES SHED BY AN OBSTACLE IN A CLOSED CAVITY

CERT-DERMES has created an experimental set-up for studying the intera ction between acoustics and coherent structures. The set-up comprises a subsonic diffuser, a rectangular wind tunnel with a square prismatic obstacle placed at an incidence to shed vortices, and a converging-di verging nozzle. The sound waves are observed to be amplified when the acoustic triggering and vortex shedding frequencies are close to one a nother. A numerical simulation using an adapted version of the KIVA co de developed at Los Alamos replicated experimental vortex shedding wit h particle dyes. The experimental and numerical Strouhal numbers for t he vortex shedding behind the obstacle are in good agreement with prev iously published results.