Flamelet based predictions and scaling laws of no-formation in turbulent hydrogen diffusion flames

摘要

the prediction of thermal NO-formation in turbulent hydrogen-air diffusion flames is studied using the laminar flamelet concept. with this concept, which is in principal vaid for fast chemical processes, the mean temperature, density and composition in the turbulent field is obtained by appropriately averaging the scalar versus mixture fraction profiels in laminar counterflowing flames (flamelets). Each of the flamelets is subject to a different fluid dynamic strethc rate, which is characterized by the strain rate. For the NO-mass fraction this averaging procedure is not applicable since the process of NO-formation is a slow process; it is kinetically limited instead of diffusion limited. Therefore, and averaged transport equation for the mean NO-mass fraction Y_NO has to be solved.