DIRECT NUMERICAL-SIMULATION OF TURBULENT REACTING FLOW USING A REDUCED HYDROGEN-OXYGEN MECHANISM

Results of direct numerical simulations of hydrogen-oxygen combustion using a partial-equilibrium chemistry scheme in three-dimensional, con stant density, decaying, isotropic turbulence are reported. The simula tions qualitatively reproduced many features of experimental results, such as superequilibrium radical species mole fractions, with temperat ure and major species mole fractions closer to chemical equilibrium. A reas of high reaction rate occurred in the simulations in sheetlike zo nes where regions of high scalar dissipation intersected the stoichiom etric surface, as would be expected for near-equilibrium or flamelet c ombustion. Simulation results were compared with predictions of the Co nditional Moment Closure model. This model was found to give good resu lts for all quantities of interest when the conditionally averaged sca lar dissipation was used in the prediction. When the nonconditioned av erage dissipation was used, the predictions compared well with the sim ulations for most of the species and temperature, but not for the reac tion rate. The comparison would be expected to improve for higher Reyn olds number flows, however.