Direct numerical simulation of triple flames by using 2-D reaction-diffusion manifold tabulation method

Abstract

The characteristics of partially-premixed flames is investigated by simulating a series of triple flames with different variations of chemical equivalent ratio. A 2-D reaction-diffusion manifold chemistry tabulation method is employed in the simulation and the results are compared with the CH4-air 19-step chemical reaction mechanism. The performance of these two mechanisms is then assessed by using direct numerical simulations coupled with GRI3.0 detailed mechanism. It is shown that both 2-D reaction-diffusion manifold table and 19-step simplified mechanism can describe the temperature and main products accurately, however, for some minor intermediary products, predictions from 2-D reaction-diffusion manifold table is observed to be better than 19-step simplified mechanism. Com-pared with the 19-step mechanism, 2-D reaction-diffusion manifold table only needs to solve only the transport equations for CO2 and N2 species, which greatly simplifies the solution process of chemical reaction and provides a reliable solution for the numerical simulation of turbulence with higher accuracy. This work indicates that as a relatively advanced kinetic simplified method, the reaction-diffusion manifold tabulation method can reduce the computational cost and at the same time retain the accuracy effectively.