Weakly Turbulent, Wrinkled Flames in Premixed Gases

Abstract

The dynamic behaviour of an intrinsically stable premixed flame front, propagating downwards in a weakly turbulent incoming flow is investigated for an arbitrary gas expansion ratio. The complete hydrodynamic problem, in which the flame appears as a free boundary, is solved analytically in the linear approximation. In this case the mutual interaction between combustion and turbulence is fully described theoretically. The response of the flame is found as a function of both the frequency and wave number content of the incoming turbulence. In addition to the gas expansion ratio, only two other parameters appear in the theory, the Markstein number (characterizing the curved flame structure) and the Froude number (based on the flame speed and the flame thickness) Sensitivity of the turbulent flame speed to the characteristics of the incoming flow as well as to these numbers is considered. The theoretical results are illustrated by comparison with some recent laboratory experiments