2008•Ranshao kexue yu jishuRequires access
Conditional Moment Closure Model of Jet Flames
Chonglin Song
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Abstract
Databases generated by direct numerical simulation(DNS) of non-premixed combustion at moderately low Reynolds numbers are used to evaluate the first-conditional moment closure(CMC) models of jet flames.Results show that the singly conditional moment closure model can well describe flame structure at moderately low scalar dissipation rates,but will overpredict flame temperature at rather high scalar dissipation rates,which indicates that the singly conditional moment closure model is unable to describe extinction events.A new conditional moment closure strategy using scalar dissipation rate as a second conditioning variable is able to well describe flame structure at any scalar dissipation rate.It is found that the nonconstant coefficients α0,β0 and γ0 in the doubly conditional moment closure modeling governing equations vary little with time.Furthermore,β0 and γ0 can be ignored compared with α0.