Turbulence in air-water systems

The experimental method proposed in this investigation is used for the study of turbulent two phase flow parameters. This method, flash photography used with a back lighting technique, is simple, accurate and most importantly nonintrusive. Its nonintrusive characteristic is attractive since it does not disturb the flow pattern. Thereby assuring that the information acquired is realistic. It can be used with most test section geometries and is not greatly limited by the fluids used in this type of experiment.;Following the development of this method, two categories of experiments were undertaken. The first set of experiments dealt with a stagnant liquid and upwardly flowing gas. It was confirmed that there exists a relationship between the following three plots: the bubble velocity, the lateral deviation, and the bubble oscillation frequency all versus the equivalent bubble diameter. This relationship is believed to be associated with the type of movements the bubble has in turbulent flow. The radial profiles of the bubble velocity and the equivalent diameter exhibited a parabolic behavior. This was an expected result since the very large bubbles, which tend to have a higher bubble velocity, rise in the center of the column. The void fraction profile showed a distinctive center peaking trend. This trend occurs since there are no strong transversal gradients in this experiment.;The second set of experiments concerned two phase flow. The same types of plots were obtained. However it was observed that there was not that strong a correlation between the plots of the bubble velocity, the lateral deviation, and the bubble oscillation frequency all versus the equivalent diameter. This trend could be possibly due to the fact that in two phase flow more dominant forces assume greater importance. The radial profiles of both the bubble velocity and the equivalent diameter revealed a parabolic behavior. The reasoning for this behavior is similar to the earlier experiment. The void fraction radial profile had a definitive wall peaking trend. This trend is attributed to the fact that strong transversal gradients are present which cause a higher concentration of bubbles near the walls of the test section.