A Study of Instabilities in Hydrogen-air Impinging Jet Flames Using Two and Three Dimensional Direct Numerical Simulations

Two and three dimensional Direct Numerical Simulations have been performed respectively to gain the insight of structure and instability of hydrogen-air impinging flames. Considering the effects of hydrogen-air chemistry, fluid convection and thermal conduction, a parametric study of buoyancy and disturbance has been studied. Results show that buoyancy is the prominent factor for flow instabilities associated with outer vortices, which dominate the flow field. The generation and propagation of a much thicker flame surface are shown in non-buoyant case. These results are prominent in two-dimensional simulations due to some assumptions. Besides, the inlet disturbance accounts for the formation of inner vortices, the asymmetric behavior of flame structure and the shear instability, as shown in detailed three-dimensional cases. It is easier to provide a better understanding by the combined approach, which can complement each other with their respective advantages in the identifications of flame structure and instability.