Control of vortex shedding and acoustic resonance of a circular cylinder in cross-flow

Abstract

This study experimentally investigates the effectiveness of a control rod in suppressing self-excited acoustic resonance within a range of Reynolds numbers (Re) spanning from $2.1$ × $10^4$ to $1.6$ × $10^5$. The investigation focuses on specific parameters, including diameter ratio ($d/D$) values of 0.1, 0.2, and 0.3; gap ratio ($G/D$) values of 0.05, 0.1, and 0.2; and angular positions ($\theta$) ranging from 0 to 180 degrees. Comparative analyses are conducted between cases featuring the control rod and a reference case (base case) without it. The near-wake flow field is characterized using Particle Image Velocimetry (PIV), and aeroacoustic response measurements are employed to quantify the aeroacoustic noise emission, particularly during self-excited acoustic resonance. Simultaneous measurements of fluctuating lift force and aeroacoustic response measurements, facilitate the quantification of energy transfer from the flow field to the acoustic field during self-excited acoustic resonance. The results reveal that the control rod’s placement significantly impacts the Strouhal periodicity, with outcomes heavily dependent on the rod’s angular orientation. At certain angular positions, the control rod reduces the sound pressure level (SPL) generated during acoustic resonance excitation. However, at different angular positions, the rod exacerbates resonance excitation. This variability is attributed to the control rod’s profound influence on the vortex core formation and the energy transfer mechanism during acoustic resonance.