Interaction of a Gaussian acoustic wave with a turbulent premixed flame

We investigate in this paper the interaction of a H-2/O-2/N-2 turbulent premixed flame with a Gaussian acoustic wave (negative pulse) in a 2-D compressible flow using Direct Numerical Simulation. Realistic chemical kinetics and transport properties are taken into account (detailed reaction scheme, multicomponent diffusion velocities, thermal diffusion, and barodiffusion). A new, direct procedure is introduced to obtain a local Rayleigh's criterion. This procedure is applicable for laminar as well as turbulent, premixed or non-premixed flames, and requires no linearization. The situations in which amplification (resp. attenuation) occurs are listed. Calculations of a turbulent flame are then carried out with and without an acoustic wave and results are recorded at the same time. By a simple difference it is possible to obtain the influence of acoustic wave/turbulent flame interaction. It is shown that the wave is wrinkled after its passage through the flame while the flame front is practically not affected. Rayleigh's criterion shows that wave amplification occurs only inside well-located, small zones. (C) 2003 The Combustion Institute. All rights reserved.