Author:
NAGATA KOUJI,KOMORI SATORU
Abstract
The effects of unstable thermal stratification and mean shear on chemical reaction and
turbulent mixing were experimentally investigated in reacting and non-reacting liquid
mixing-layer flows downstream of a turbulence-generating grid. Experiments were
carried out under three conditions: unsheared neutrally stratified, unsheared unstably
stratified and sheared neutrally stratified. Instantaneous velocity and concentration
were simultaneously measured using the combination of a laser-Doppler velocimeter
and a laser-induced fluorescence technique. The results show that the turbulent mixing
is enhanced at both large and small scales by buoyancy under unstably stratified
conditions and therefore the chemical reaction is strongly promoted. The mean shear
acts to enhance the turbulent mixing mainly at large scales. However, the chemical
reaction rate in the sheared flow is not as large as in the unstably stratified case with
the same turbulence level, since the mixing at small scales in the sheared neutrally
stratified flow is weaker than that in the unsheared unstably stratified flow. The
unstable stratification is regarded as a better tool to attain unsheared mixing since
the shearing stress acting on the fluid is much weaker in the unstably stratified flow
than in the sheared flow.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Cited by
26 articles.
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