INITIATION OF COMBUSTION IN LEAN MIXTURES BY FLAME JETS

Flame jets produced by Pulsed Combustion Jet (PCJ) systems are particu larly suited for initiating combustion in lean fuel-air mixtures. Pres ented here is a detailed investigation of performance characteristics of a PCJ system. The progress of combustion in the cavity of a generat or was observed by schlieren photography of the events occurring in th e interior of a rectangular cavity simulator fitted with transparent w indows. Electric properties of the jet plume were measured by an elect rostatic probe. Schlieren photographs revealed that products of combus tion are discharged through the orifice before the combustion process can spread throughout the volume of the cavity. Signals of the electro static probe showed that ejection of incomplete combustion products fr om the cavity is principally governed by the duration of spark dischar ge. In the jet, the exothermic process decays at first and then become s reestablished inside large scale vortex structures in the jet plume.