Experiments and analyses were performed to contribute to a basic understanding of the holding of flame in a stream of a combustible gas mixture by a small gas jet directed upstream. The main stream, a mixture of natural gas and air, entered a cylindrical transparent test section at uniform velocity. A flame-holding jet of air was directed counter to the stream along the axis of the test section. Observations of the flow field and flame behavior were made by means of time-exposure photographs, high-speed motion pictures, and spark shadow¬graphs. A pilot flame was delineated, and its significant time-averaged dimensions were noted as a function of jet and main-stream velocities. New evidence was obtained indicating the occurrence of recirculation. Transmission of flame from the pilot to the main stream is accomplished through a mixture continuously shedding from the pilot flame. Rough burning near the rich stability limit occurs when significant portions of the shedding mixture are not flammable. The influence of nonuniform fuel concentration patterns in the main stream, on flame .stability limits was also investigated. Interpretation of the data leads to conclusions which conflict with a currently held mechanism for reversed-jet flame stabilization. A mechanism is proposed which is plausible in the light of current observations. Further research would be desirable.to broaden. the basic understanding of the stabilization process.;". .nAn analytical comparison was made of the relative performance of jet and conventional flame holders in the afterburner of a turbojet aircraft. A representative set of flight and basic engine performance"'' characteristics was assumed, together with a- range of afterburner operating parameters. For some combinations of parameters, the fuel consumption of the conventional afterburner exceeded that of the jet type over three percent; An operational trial of the jet flame holder after-burner is recommended.
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