Direct numerical simulation of non-premixed syngas burning with detailed chemistry

Abstract

H2/CO syngas non-premixed impinging jet flames were studied using three-dimensional direct numerical simulation (DNS) and flamelet generated manifolds (FGMs) based on detailed chemical kinetics. The computational domain employed has a size of four jet nozzle diameters in the streamwise direction and 12 jet nozzle diameters in the cross-streamwise direction. The results presented in this study were performed using a uniform Cartesian grid with 200×600×600 points. The Reynolds number used was Re=2000, based on the reference quantities. The spatial discretisation was carried out using a sixth-order accurate compact finite difference scheme and the discretised equations were time-advanced using a third-order accurate fully explicit compact-storage Runge–Kutta scheme. Results show that the ratio of H2 and CO in the syngas mixture significantly affects the flame characteristics including the near-wall flame structure. The high diffusivity of H2-rich syngas flame leads to form weaker vortices and a thicker flame. In contrast, CO-rich syngas flame leads to form a thinner flame with strong wrinkles. Moreover, the DNS results suggest that the preferential diffusion influences the local flame structure for the simulated low Reynolds number H2 flame.