On the linear hydrodynamic stability and response of premixed flames in stagnation-point flows

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Abstract

Using inviscid potential models as computational tool and means to get qualitative insights, we first qualitatively study the linear stability of strained premixed flames held in 2-dimensional stagnation-point flows. We consider three configurations, in which fresh gases respectively impinge: (a) burned ones, (b) a wall, (c) another jet of fresh gas. We analytically suggest that:-if intense enough, flow divergence can stabilize disturbances with wavevector normal to directions of strain-any positive stretch always stabilizes those wrinkles with wavevectors parallel to direction of positive strain, as a result of two purely kinematic effects: wavelength increase due to tangential stretch, and stability to planar disturbances.-the least stable modes of wrinkling are antisymmetric disturbances of twin-fronts (case c) and configuration (b) is the most stable one. Lastly, we qualitatively study the linear response of axisymmetrically stretched flames-which are always linearly stable-to incoming random velocity fluctuations. Ensemble-averaged amplitude of wrinkling are theoretically estimated and we indicate a statistical tendency for twin fronts to avoid one another.

Original languageEnglish
Pages (from-to)37-44
Number of pages8
JournalSymposium (International) on Combustion
Volume24
Issue number1
DOIs
StatePublished - 1992

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