Experimental Study on Bubble Acoustic Characteristics of Elliptical Nozzles

Abstract

Bubble acoustic signals were reported experimentally using five different nozzles with the same exit cross-sections. The bubble morphology was captured by a home-made experiment setup, which could synchronously obtain images of two perpendicular directions. Short-Time Fourier Transform and synchronization of video and audio were adopted to analyse the acoustic signal. Results demonstrated that the sound pressure of symmetrical bubble formation was higher than that of asymmetrical bubble formation, while the sound pressure of asymmetrical bubble formation was higher than that of the bubble with an unapparent necking fracture detached from the nozzle of the aspect ratio is 4:1. Furthermore, the last bubble of bubble chains would change the shape and decay rate of the acoustic signal due to the difference in the period of bubble formation. These studies can provide more effective information to predict the leaks from undersea gas pipelines, seabed methane reserves, and carbon capture and storage facilities.