Experimental Study on Behavior of a Flame Entering into a Narrow Channel

A behavior of a flame propagating through a narrow channel is of importance, since this phenomenon is concerned with a quenching of the flame when heat losses by convective heat transfer or radiative one to a wall of channel are dominant and temperature behind the flame is not enough to increase that of unburned gases. Since, this phenomenon is also related to a safety-engineering problem where combustible gaseous mixture is handled, a device applying a narrow channel in a pipe might be one of useful technique to prevent the flame from propagating. Experiments were conducted to investigate a behavior of the flame propagating through a narrow channel, which connects two rectangular combustion chambers. The behavior of the flame was visualized using schlieren optical technique with an aid of high-speed video camera. In this study, an equivalence ratio of methane-air mixture, initial pressure and a width of the channel were varied in order to investigate effects of these parameters on characteristics of the flame propagation. As a result, the behavior of the flame entering into the narrow channel was classified into two phenomena, i.e. (i) the flame was quenched inside the narrow channel and combustion wave was not propagated into the downstream chamber, which results in just an emission of burned gaseous jet to the downstream chamber, (ii) the flame was propagated through the channel without quenching, which produced a high-pressure at both chambers