ON THE DISPLACEMENT EFFECTS OF LAMINAR FLAMES

Asymptotic methods for large Reynolds numbers are used to show that through displacement effects the heat release associated with both premixed and nonpremixed laminar flames in laboratory counterflow configurations result in significant alterations of the rate of strain attributed to the flow external to the flame. The analysis involves the classical sequence of calculating the first order inviscid flow, which in the present case yields the currently available expression for the rate of strain, the first order inner flow describing the structure of the flame including the displacement thickness of the flame and finally the second order outer flow yielding the correction to the rate of strain. Comparisons are made with some experimental and fully numerical results to demonstrate the significant alterations in the rate of strain produced by the displacement effects associated with heat release.