ASA 125th Meeting Ottawa 1993 May

2aUW15. Acoustic characterization of a bubble injected into a fully developed turbulent flow field.

Ali R. Kolaini

Ken Markewicz

Veera Rajendran

Natl. Ctr. for Phys. Acoust., Univ. of Mississippi, Oxford, MS 38677

An experiment was designed to investigate the characteristics of sound produced by the turbulent excitation of bubbles. By injecting a bubble into a fully developed turbulent flow, generated by a submerged axisymmetric horizontal water jet, the excitation of bubbles and shear-induced fission/fusion may occur. In the case of shear-induced bubble distortion by a turbulent jet, nonlinear coupling between volume pulsation and surface oscillations occur at exactly the same frequency as the radial breathing mode of the bubble. Particle tracking velocimetry (PTV) is used to characterize the turbulent flow field. Two high-speed Kodak Ekta-Pro video cameras are used to capture, simultaneously, several 180-x180-x10-mm illuminated regions along the jet. An 8-W argon ion laser is utilized for illumination. The method provides not only a visualization of the various patterns and structures of the turbulent flow, but also yields quantitative instantaneous velocity data of the flow containing the bubble. The role of the turbulent flow characteristics in determining the acoustical bubble response is discussed. [Work supported by ONR.]