ON THE DYNAMICS OF ANCHORED FLAMES

The dynamic and the shape of an anchored premixed flame are analyzed as the result of the sum of wrinkles convected along the flame and of the wrinkles locally induced by the flow. The linear approximation leads to an interference integral that describes the shape as a function of time. Three applications are given: (1) An homogeneous oscillation of the flow induces a traveling wave propagating inside a stationary envelope. Its main feature is a spatial modulation with bottlenecks (nodes in one case) regularly spaced with a wavelength equal to the convecting velocity times the period of the modulation. Experiments are presented and discussed. (2) The modulation of the flame by a Benard Von Karman street is calculated for small wrinkling and compared to experments. (3) The tuebulent thickness of anchored flames is calculated for homogeneous and isotropic turbulence. The result is given as a function of the R11 space-time correlation function. The conclusion points out the new insight from a physical point of view and the limitation of such an approach. © 1990.