We study the process of combustion wave propagation in microchannel. The wave appeared due to ignition of premixed gases which were inputted from the one side of microchannel. It was supposed that the microchannel has constriction. The narrowest part is located in the middle of the tube and its diameter in 2 times less the widest diameter at the ends of microchannel. For this problem experiments were conducted on the sudden converging microchannel. And the simulations for both sudden and smoothly converging microchannels were performed. Numerical simulations were conducted in axisymmetric formulation with respect to horizontal plane. Combustion process flows with heat losses since microchannel walls are considered constant and equal to the ambient temperature. The flow was assumed laminar. Results of this work can be apply, for example, for studying combustion waves in porous media on the assumption of that the porous media is the set of such microchannels.
Gas mixture was inputted with different inlet velocity. It was found out that this velocity plays critical role in further flame propagation. Flame can either pass through the constriction or get extinguish into constriction or get extinguish before it reaches constriction. Both in experiment and numerical simulations the velocity of flame propagation through the microchannel is approximately 0.01 m/s. For higher velocity the flame gets extinguish because of nozzle effect of constriction. Other conditions influencing on flame propagation, for example such as equivalence ratio, were considered. The flame propagation velocity and maximum flame temperature depending on axial distance and time were analyzed as well. Comparison between microchannels with two types of constriction was conducted. In a case of smoothly converging microchannel the flame propagates a longer way before it gets extinguish because combustion wave does not lose its heat and velocity suddenly as it would be if the microchannel walls have a step.