Effects of fluid-structure interaction on trailing-edge noise

Abstract

This study numerically investigates the effects of fluid-structure interaction (FSI) on the trailing-edge noise, particularly for the cases of wake instability and Karman vortex shedding. The trailing edge is modeled as a flat plate with an elastic cantilever end and its flow-induced vibration is solved by an eigertmode analysis with the Galerkin method. The flow and sound coupled in the FSI analysis are computed on the moving grid by a direct numerical simulation (DNS) procedure. The computed result of wake instability shows that when the first-eigenmode natural frequency ro, of the cantilever is close to be resonant with the wake characteristic frequency oj,, the sound pressure level (SPQ is significantly reduced by 20 dB at omega(n)/omega(c),=0.95, or increased by 15 dB at omega(n)/omega(c)=1.05, for all angles. For the Karman vortex shedding, a similar frequency modulation occurs via FSI, if omega(n) is close to omega c. The flow and acoustic details are somewhat different for this case but a considerable noise reduction was also possible for angles from -120 degrees to +120 degrees.