Soot, turbulence, and combustion chemistry interactions occur at small scales, yet Large Eddy Simulation (LES) only resolves the larger, geometry-dependent features of a turbulent flow. Therefore, subfilter models for the soot population, turbulent fluctuations, and thermochemical quantities must be developed based on physically sound principles. Turbulence-chemistry interactions have been modeled previously [Mueller and Pitsch Phys. Fluids 23 (2011)] through a subfilter probability density function (PDF) that joins a PDF of the thermochemical variables with a conditional PDF of the soot scalars on the thermochemical variables. An argument was made that the characteristic time of soot formation is much longer than the time scales of the heat-releasing chemistry, so the conditional PDF can be reduced to a marginal PDF of the soot scalars. Soot-turbulence interactions are then accounted for by incorporating subfilter intermittency in the marginal PDF. However, this approximation fails to account for the rapid oxidation of soot. In this work, the conditional PDF of the soot scalars has been modified to include a dependence on mixture fraction (a thermochemical variable). Predictions of soot evolution in LES using this modified subfilter PDF will be compared to experimental measurements of turbulent nonpremixed ethylene/hydrogen/nitrogen jet flames.
|Original language||English (US)|
|Title of host publication||2016 Spring Technical Meeting of the Eastern States Section of the Combustion Institute, ESSCI 2016|
|Publisher||Eastern States Section of the Combustion Institute|
|State||Published - Jan 1 2016|