Large eddy simulation of plasma-assisted ignition and combustion in a coaxial jet combustor

To study the effect of plasma O3 on the combustion-supporting process for a coaxial jet combustor, large eddy simulation (LES)-partially stirred reactor (PaSR) simulation of a methane/air turbulent diffusion combustion was carried out based on OpenFOAM open-source software platform. The prediction of the turbulent diffusion flame was verified, and the results are in good agreement with the experiment data. Then the effect of air discharge product (i.e., O3) on the methane ignition and combustion process was investigated using plasma-assisted combustion model by 341 steps detailed reaction mechanism. The results show that the addition of O3 can increase the speed of flame propagation and accelerate the ignition process of methane combustion. It is also found that the vortex structure with O3 is more continuous in the recirculation zone, and the flame recirculation zone with O3 is closer to the inlet. The effect of O3 on enhanced combustion is more obvious in the low-temperature region, while the axial-velocity ratio with O3 is considerably improved in the high-temperature region. Besides, the plasma O3 will reduce the fluctuation of vx′vx’, especially at the peak point, which will tend to stabilize the recirculation zone. •The flame development with O3 is faster than that without O3.•The vortex structure with O3 is more continuous in the recirculation zone, and the flame recirculation zone moves forward.•The enhanced combustion effect of O3 is more obvious in the low-temperature region.•The plasma O3 will reduce the fluctuation of vx′vx’, especially at the peak point.