Non -Intrusive Characterization of a Dispersed, Bubbly, Axisymmetric Jet.

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This study investigated the effects of bubble size and phase distribution on the liquid and bubble flow fields in a dispersed, bubbly axisymmetric jet. Of primary interest was the interaction of the bubbles with large-scale structures in the developing region of the jet. Measurements were made non-intrusively via Laser Doppler Velocimetry (LDV), Phase-Doppler Analysis (PDA) and video imaging techniques. Liquid Reynolds' numbers were varied from approximately 6,000 to 18,000 while gas volume fraction ranged from 0 to 3%. Bubble sizes varied from approximately 600 mum to 1500 mum. Axial mean velocities and RMS fluctuations have been reported for the liquid phase. Axial and radial mean velocities and RMS fluctuations have been reported for the bubbles. Measurements have been made along the centerline and radially at downstream locations of x/Djet = 0.08, 4, 8, and 16. The effects of bubble size and phase distribution on the development of the axisymmetric shear layer as well as liquid phase and bubble velocity properties in general have been examined. These data have been put into perspective with respect to traditional two-phase flow parameters as well as previous experimental, analytical and computational works. Bubble/turbulence interaction was examined in the context of the turbulent kinetic energy spectrum and a critical wave number corresponding to bubble diameter was found above which turbulence was enhanced, and below which it was attenuated.