Bubble-induced noise and vibration in cylindrical shell filled with liquid nitrogen

Abstract

Bubble-induced vibration is a very crucial aspect in some critical systems like laser interferometer gravitational-wave observatory. Recently, laser interferometer gravitational-wave observatory detected the gravitational wave produced due to the merger of two black holes. To detect the other universe collision event due to other binary pairs like neutron stars, black holes or combination, the sensitivity of the detector should be very high. The sensitivity depends on the reduction of the noise present in the detector system / components. Liquid nitrogen cryopump is also one of the sources for the noise. This noise has been produced due to the bubble structure interaction. The present work analyzes the bubble generated noise spectrum level and its acoustic effect due to induced vibration. The spectrum levels considering force, acceleration, velocity, and displacement effect have been studied in detail for a thin annular fluid (LN2) filled cylindrical shell. It is assumed that the structure of cylindrical shell is homogeneous as well as isotropic. The noise level generated due to radial force excitation resulting from bubble collision has been found to be in the range of −85 dB to −45 dB at a lower resonance frequency.