Numerical study of hydrogen/air flame jet ignition for the dependence of the equivalent ratio

Jet ignition is a phenomenon that flame is ignited to propagate in a deriver chamber (DC) and after it passes through an orifice or nozzle, it may or may not distinguishes once and becomes a stronger jet flame in a receiver chamber (RC). Experimental study of flame jet ignition is performed at many places in Japan and foreign countries to find out that equivalence ratio and orifice diameter influence jet ignition phenomena. However the detailed mechanism of jet ignition has not been clarified well. The present study shows numerically the influence of equivalence ratio of hydrogen/air mixture and orifice diameter between two rooms (DC and RC) on jet ignition using two different combustion chamber models and a commercial code of CFD++. The results show that so called auto ignition, an ignition occurs before flame goes into RC from DC, is not seen in all cases, but usual jet ignition is seen for two equivalence ratios (0.340 and 0.404). The jet ignition is not seen when the orifice size of 14.0mm and the smaller size of RC than DC are used. In the case of jet ignition it is found that the disturbances by unreacted mixture and pressure waves from DC provide the jet ignition atmosphere in RC.