A method for shortening ignition delay of hydrocarbon fuel-air mixture

A combination facility,which consists of a shock tunnel and a shock tube,was used for studying ignition and supersonic combustion of premixed hydrocarbon fuel-air mixture.In order to shorten the ignition delay time of hydrocarbon fuel-air mixture,an atomized and vaporized hydrocarbon fuel (gasoline) was preheated by shock reflections between the entrance of nozzle and contact surface,which was located between working gas and driver gas,in the shock tunnel.In addition, a hot, burned gas generated from the shock tube was used as pilot flame for igniting the premixed and preheated supersonic hydrocarbon-air mixture generated in the shock tunnel.A schlieren system was used for flow visualization of the flame propagating in a supersonic,combustible flow.By means of these methods mentioned above, the ignition delay time of the supersonic hydrocarbon-air mixture can be shortened to less than 0.2 ms, and the speed of flame propagation relative to the supersonic,combustible gas was obtained.