TY - JOUR

T1 - Analysis of impinging wall effects on hydrogen non-premixed flame

AU - Dinesh, K. K. J. Ranga

AU - Jiang, X.

AU - van Oijen, J. A.

PY - 2012

Y1 - 2012

N2 - Investigations of the flame-vortex and flame-wall interactions have been performed for hydrogen impinging non-premixed flame at a Reynolds number of 2000 and a nozzle-to-plate distance of 4 jet diameters by direct numerical simulation (DNS) and flamelet generated manifold (FGM) based on detailed chemical kinetics. The results presented in this study were obtained from simulations using a uniform Cartesian grid with 200 x 600 x 600 points. The spatial discretization was carried out using a sixth-order accurate compact finite difference scheme, and the discretized equations were advanced using a third-order accurate fully explicit compact-storage Runge-Kutta scheme. The results show that the inner vortical structures dominate the mixing of the primary jet for the nonbuoyant case, while outer vortical structures dominate over the inner vortical structures in the flow fields of the buoyant cases. The formation of vortical structures due to buoyancy has a direct impact on the flow patterns in both the primary and wall jet streams, which in turn affects the flame temperature and the near-wall heat transfer. It has been found that the buoyancy instability plays a key role in the formation of the much wider and higher value wall heat flux compared with the nonbuoyant case, while external perturbation does not play a significant role. The computational results show an increased wall heat flux with the presence of buoyancy.

AB - Investigations of the flame-vortex and flame-wall interactions have been performed for hydrogen impinging non-premixed flame at a Reynolds number of 2000 and a nozzle-to-plate distance of 4 jet diameters by direct numerical simulation (DNS) and flamelet generated manifold (FGM) based on detailed chemical kinetics. The results presented in this study were obtained from simulations using a uniform Cartesian grid with 200 x 600 x 600 points. The spatial discretization was carried out using a sixth-order accurate compact finite difference scheme, and the discretized equations were advanced using a third-order accurate fully explicit compact-storage Runge-Kutta scheme. The results show that the inner vortical structures dominate the mixing of the primary jet for the nonbuoyant case, while outer vortical structures dominate over the inner vortical structures in the flow fields of the buoyant cases. The formation of vortical structures due to buoyancy has a direct impact on the flow patterns in both the primary and wall jet streams, which in turn affects the flame temperature and the near-wall heat transfer. It has been found that the buoyancy instability plays a key role in the formation of the much wider and higher value wall heat flux compared with the nonbuoyant case, while external perturbation does not play a significant role. The computational results show an increased wall heat flux with the presence of buoyancy.

KW - Buoyancy

KW - DNS

KW - Hydrogen combustion

KW - Impinging jet

KW - Wall heat flux

U2 - 10.1080/00102202.2012.679715

DO - 10.1080/00102202.2012.679715

M3 - Journal article

VL - 184

SP - 1244

EP - 1268

JO - Combustion Science and Technology

JF - Combustion Science and Technology

SN - 0010-2202

IS - 9

ER -