INCREASE OF THE FLAME VELOCITY IN A ROTATING GAS AND THE RENORMALIZATION APPROACH TO TURBULENT BURNING

Abstract

Propagation of a premixed flame in a rotating gas (along the vortex axis) is considered for the cases of both small and realistically large density drop at the flame front. A nonlinear equation for the flame front is derived, which takes into account the centrifugal force of the vortex, the intrinsic Darrieus–Landau instability of the flame front and the finite flame thickness. Influence of the gas rotation on the flame velocity is investigated numerically as a solution to an eigenvalue problem on the basis of the derived equation. In the domain of weak turbulence such a method provides much better accuracy than direct numerical simulations performed earlier for a similar problem. The solution obtained supplies important information for the renormalization theory of turbulent flame velocity. It is found that turbulent vortices parallel to the direction of flame propagation are more important than the perpendicular ones, which were considered traditionally as the main reason for flame wrinkling. As an illustration, velocity of a strongly turbulent flame is calculated and compared to the experimental results.

Keywords:

• Centrifugal force
• Premixed flames
• The Darrieus–Landau instability
• Turbulent burning

This work has been supported in part by the Swedish Research Council (VR) and by the Kempe Foundation.