Effects of short splitter plates on vortex shedding and sound generation in flow past two side-by-side square cylinders

Abstract

Effects of short splitter plates on vortex shedding and sound generation in a low subsonic flow past two side-by-side square cylinders were examined experimentally at Reynolds numbers ${{{Re}}} = 1.0 - 3.3 \times 10^4$. The experiment was mainly conducted with the center-to-center distance between the two cylinders of 3.6d (d is the side length of a square cylinder) where vortex shedding from the two cylinders was synchronized with anti-phase relation, generating a quadrupole-like sound source that radiated in-phase sound in the far field. The results showed that the attachment of short splitter plates whose length (c) was ≤0.5d could reduce the sound pressure level of Aeolian tone significantly. Even with the shortest splitter plates of $c{/}d=0.1$, SPL was reduced by 6 dB at Mach number $M_{\infty }=0.15$. This was in contrast to the case of a single square cylinder, for which the attachment of a short splitter plate <0.2d led to no noticeable noise reduction. It was also shown that even when short splitter plates with a spanwise length as long as or less than the correlation length of shed vortices were attached on the two cylinders in a staggered array, the anti-phase vortex shedding and the corresponding in-phase sound radiation were still dominant.