Young J. Moon
The Journal of Mechanical Science and Technology, vol. 22, no. 7, pp.1426-1435, 2008

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 eigenmode 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 ωn of the cantilever is close to be resonant with the wake characteristic frequency ωc, the sound pressure level (SPL) is significantly reduced by 20 dB at ωn/ωc=0.95, or increased by 15 dB at ωn/ωc=1.05, for all angles. For the Karman vortex shedding, a similar frequency modulation occurs via FSI, if ωn is close to ωc. The flow and acoustic details are somewhat different for this case but a considerable noise reduction was also possible for angles from -120º to +120º.

Keyword : Trailing-edge noise reduction; Fluid-structure interaction; Frequency modulation; Wake instability; Karman vortex shedding