Comparison Between Two Highly Turbulent Flames Having Very Different Laminar Burning Velocities

Stationary jet burners, with Bunsen or V-shaped type flame are widely used for the study of premixed gas combustion. Since they are supposed to be simple configurations, they appear to the modeler scientist as a good test case to validate turbulent combustion equations closure assumptions. Modern diagnostic tools, such as laser Doppler anemometry /1/ or fine wire thermocouple temperature measurements /2/ have pointed out two essential features: a turbulence increase when crossing the combustion region and a counter-gradient diffusion. This helped to build the concept of “flamelet” combustion, where the combustion zone is seen as a region where a moving thin front, more or less corrugated, separates the fresh from burnt gas. To get a better knowledge of this flame front displacement, along with turbulence-combustion interaction, a statistical data processing involving the probability density function of the variables (PDF) was introduced /3,4,5,6/, and taken into account by the models, the most famous being the BLM model /7/.