Chemical closure and burning rates in premixed turbulent flames

✍ Scribed by F.C. Gouldin; P.C. Miles

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 712 KB
• Volume: 100
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(94)00121-8

✦ Synopsis

Chemical closure for premixed turbulent flames is considered, and with a small number of assumptions regarding its form, a model expression for the mean rate of product formation is obtained: (w } = C?(c }(1 -(c)) to fourth order in ((c) -1/2), with Cp a proportionality factor. Any model regardless of its physical and chemical basis should give this result if the aforementioned assumptions are satisfied. The burning rate integral, Br, is introduced, and a relationship between B r and Cp is developed: By = C?ln where l B is a measure of the flame thickness. It follows that measurements of Bz can be used to find Cp, and that measurements of this type for a broad range of conditions can provide an empirical closure for (w } good to fourth order in (<c} -1/2). A method for measuring Br based on a control volume analysis and the use of conditional mean velocities is proposed and demonstrated with data from Miles . The model expression for (w) is specialized to the flamelet regime of turbulent combustion, and the result obtained is similar to the Bray, Moss, Champion, and Libby crossing density model expression. A clear physical interpretation for C?, valid for the flamelet regime, is offered.