Flame Dynamics Maps for Lean Hydrogen-Air Combustion in a Heated Micro channel

In the present work, flame dynamics are extracted for lean hydrogen-air premixed combustion in a heated microchannel using numerical simulation. In order to simulate the combustion phenomenon at this scale, Navier-Stokes equations along with energy and species conservation equations are considered by formulation of a low Mach number and taking account of detail chemical kinetics. In the present work, three flame dynamics including repetitive ignition-extinction flame, steady symmetric flame and asymmetric steady flame are observed. Effects of inlet flow velocity, equivalence ratio, and channel width on the flame dynamics are investigated. Repetitive ignition-extinction flame is observed at low inlet velocities close to the lower flammability limit. By increasing the inlet flow velocity and creating a balance between the reaction time and fluid residence time in the channel, a steady symmetric flame is shown in the channel. In this situation, the maximum temperature and mass fraction of species are located on the symmetry line of the channel. By increasing the inlet flow velocity in a same channel width, the flame moves toward downstream at the symmetry line of channel and stretches near the wall.Hence, the surface of the flame front is susceptible to instability and becomes unstable due to flow perturbations. The flame dynamics maps in the small scales are presented for the hydrogen-air mixture based on three parameters of inlet flow velocity, equivalence ratio and channel width in the microchannel.