Initiation of Combustion in Lean Mixtures by Flame Jets

Abstract

Flame jets produced by Pulsed Combustion Jet (PCJ) systems are particularly suited for initiating combustion in lean fuel-air mixtures. Presented here is a detailed investigation of performance characteristics of a PCJ system. The progress of combustion in the cavity of a generator was observed by schlieren photography of the events occurring in the interior of a rectangular cavity simulator fitted with transparent windows. Electric properties of the jet plume were measured by an electrostatic probe. Schlieren photographs revealed that products of combustion are discharged through the orifice before the combustion process can spread throughout the volume of the cavity. Signals of the electrostatic probe showed that ejection of incomplete combustion products from the cavity is principally governed by the duration of spark discharge. In the jet, the exothermic process decays at first and then becomes reestablished inside large scale vortex structures in the jet plume.