A Study of Flow and Mixing in Bubbly Gas-Liquid Pipe Flow Generated by a Grid

Abstract

<span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>The spreading of a tracer in a bubbly two-phase grid-generated turbulent flow system</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>is studied. In this work both particle image velocimetry (PIV) and planer laser-induced</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>fluorescence (PLIF) are used to study the effect of the dispersed phase flow rate on the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>mixing characteristics of the tracer. The turbulent intensity of the continuous phase in</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>the bubbly two-phase grid-generated turbulent flow is close to isotropic, and increasing</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>the gas void fraction reduces the degree of non-isotropicity. The self-similarity of mean</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>and RMS values of the cross-stream concentration distribution is observed. A new</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>mathematical model is suggested to describe the self-similarity of the cross-stream</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>profiles of the mean concentration based on two separate Gaussian curves into the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>central and outer region of the flow. The turbulent diffusivity is calculated using the</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>Taylor hypothesis, which is based on the growth of the variance of the cross-stream</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>profiles of the mean concentration, with a position along the direction of the flow. An</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>increase in the void fraction does not affect the diffusivity of the superimposed</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>distribution of the plume in the central region, however it did increase in the outer</em> <span style="font-size: 10pt; color: #000000; font-style: normal; font-variant: normal;"><em>region.</em> </span></span></span></span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /></span></span>