The mechanism of flame propagation affected by flow/shock wave in a confined combustion chamber equipped with a perforated plate

Abstract

The whole evolution of flame propagation in a confined combustion chamber was firstly experimentally observed in a newly designed experimental apparatus equipped with a perforated plate. The effect of the flame-flow/acoustic/shock wave interaction on the flame propagation was studied. The experiment was conducted with a stoichiometric hydrogen-air mixture. According to the flame morphology and the flame tip velocity, the whole evolution of flame propagation in the experimental apparatus was classified into the following three stages: laminar flame, jet flame and turbulent flame. In the present work, different flame propagation modes were obtained in different conditions. Depending on the initial pressure, three different flame propagation modes were observed. At an initial pressure of 1 bar, the flame propagation after perforated plate was mainly controlled by the interactions of the flame and combustion-generated flow ahead of the flame front. As initial pressures went up to 3 bar and 5 bar, shock waves were clearly observed ahead of the flame, which played a significant role on the flame propagation. The flame decelerated sharply and even propagated backwards, induced by the flame-shock wave interactions. Depending on the intensity of the shock wave, the backward-propagation velocity was higher at 5 bar with a stronger shock wave. In addition, the pressure oscillation at different initial pressures was discussed.