Investigation of the underlying cause of the interaction between acoustic resonance and fluidelastic instability in normal triangular tube arrays

The interaction between fluidelastic instability and acoustic resonance in a normal triangular tube array has been previously quantified, although no physical mechanism was identified. In this study interaction between fluidelastic instability and acoustic resonance is extended to a second array. In addition, to assess the interaction between fluidelastic instability and acoustic resonance two possibilities are examined. The first examines the effect of acoustic resonance on the static fluid forces on a stationary cylinder and the second the effect of acoustic resonance on the time delay between tube motion and the resultant flow reorganisation close to the measurement cylinder. It is found that acoustic resonance did not modify the static fluid force. Acoustic resonance is seen to modify the time delay between tube motion and flow field around the cylinder. It is proposed that acoustic streaming is affecting the time delay process resulting in the drop in fluidelastic vibration amplitude observed.