Turbulence and Shear Flow Phenomena -1 First International Symposium

ISBN Print: 1-56700-135-1

TURBULENCE MODIFICATION IN BUBBLE IMPINGING JET

Abstract

The experimental study of local structure of axisymmetric impinging jet has been performed for single-phase and two-phase conditions. On the basis of electrodiffusion measurements of flow characteristics the analysis of jet's turbulent structure was made. The effect of external periodical forcing and gas saturation on the wall shear stress values, coherent and random components of turbulence was studied. The periodical forcing of a jet at the frequencies which lie inside the range of jet's sensitivity leads to the resonant amplification of the large-scale vortex structures in the jet shear layer. The gas saturation results to a significant increase in the average friction at the impingement surface. The coherent structures in the jet shear layer suppress strongly by small gas bubbles and at large void fractions they are not discernible in the spectral distributions.