Abstract: The flame front instability characteristics of the combustion of the methane/air premixed gas in the porous media burner were investigated. The experiment results showed that in a particle bed with the ball diameter of 6mm， the flame front changes from the regular symmetrical flame to the inclined flame gradually and split into two areas finally in a given initial uneven preheated zone when the equivalent ratio is 041， and the flow velocity is 042m/s. When the particle bed was arranged， the balls were tamped down to decrease the uneven distribution of porosity. The initially uneven preheated areas in the even distribution of the porosity caused the flame propagated unstably and misfired in the end. Even though the given initial preheated area was even， the flame front was still somewhat unsymmetrical. The results showed that the uneven structure of the particle bed is the main reason that the flame front inclines in the filtration combustion and the initial uneven factor accelerates the instability of the flame propagation.

Key words: porous media, filtration combustion, combustion propagation, instability, experimental study