Numerical simulation of growth of flame formed in a two-dimensional mixing layer (4th report, effects of diffusion flame on mixing properties)

The mixing properties of a two-dimensional reacting shear layer have been studied numerically. Effects of heat release by combustion on the mixing properties have been discussed based on the viewpoint of the transport of vorticity. The numerical simulation is concerned with an unstable, two-dimensional, two-stream, spatially developing, confined reacting shear layer. The numerical method is based on the modified HSMAC method which can handle the change in temperature. The chemical model is a one-step irreversible methane-oxygen reaction with a finite reaction rate defined by the Arrhenius law. The numerical results have revealed that in the reacting mixing layer the vorticity thickness and the carbon element mixing layer thickness defined by the difference in the carbon element mixture fraction of 99% between the fuel and the oxidizer flows, increase in comparison to the cold mixing layer. The baroclinic torque suppresses the vorticity and the viscous term to increase the vorticity thickness.