Wake structures and acoustic resonance excitation of a single finned cylinder in cross-flow

Frequency lock-in mechanism in flow-induced acoustic resonance of a cylinder in a flow duct

“…It is obvious that if the flow velocity further goes up, the vortex shedding will be locked onto higher-order acoustic modes. Although the higher-order lock-in phenomenon is not studied in the present work, it has been observed by previous experiment (Arafa & Mohany 2019). It is the lock-in regime that characterizes the acoustic resonance.…”

“…Besides, it should be noted that the flow velocity corresponding to the maximum resonant sound pressure locates neither to where the free vortex shedding frequency is equal to the inherent β-mode frequency (U r ≈ 4.98), nor at the end of the lockin region (U r = 5.72). This phenomenon has been detected in various experimental observations (Mohany & Ziada 2009, 2011Arafa & Mohany 2019), however, there is still a lack of a reasonable explanation to the relevance of the maximum sound pressure and the lock-in behaviour of vortex and resonant sound. Next, we will try to explore and understand the reasons behind the above phenomena, based on the present physical model.…”

“…Extensive experimental results reveal that the acoustic resonance is commonly excited by the vortex shedding with Reynolds numbers ranging from 10 4 to 10 5 (Mohany & Ziada 2009, 2011Arafa & Mohany 2019;Shaaban & Mohany 2019). The wake flow behind the cylinder is essentially three-dimensional (3-D), however, during the acoustic resonance the wake flow becomes predominantly two-dimensional (2-D) as the vortex shedding along the spanwise direction is highly synchronized by the resonant sound (Blevins 1985;Mohany & Ziada 2011).…”