Numerical study of the effect of jet velocity on methane-oxygen confined inverse diffusion flame in a 4 Lug-Bolt array

The effect of jet injection velocities in a methane-oxygen confined inverse diffusion flame is numerically analyzed. The case study considers a 4 Lug-Bolt array burner where oxygen is injected by one central nozzle and where methane is injected by four peripheral nozzles. The simulations are conducted with the Reynolds-averaged Navier-Stokes technique, and the turbulence effect is modeled with the realizable k-ε model. In addition, the eddy dissipation model is implemented to calculate the effect of the turbulent chemical reaction rate. Results show that the essential mixture mechanisms are the recirculation zone and the central injection velocity, having a relevant participation on perturbations called instabilities. However, the perturbations could interfere with the mixing process on the braid zone through the drag-impulse effect (Re_O2 less than 2500). The instabilities could also affect the flame front far away from the reaction zone at injection velocities of Re_O2 between 2500 and 5000. If Re_O2 is greater than 5000, the reaction layer may induce intense perturbations that affect the combustion ignition zone, and Re_O2 being greater than 10000 might lead to the local quench-flickering discontinuity effect, ripping apart the reaction layer and the complete flame blowout (Re_O2 greater than 15000).