I was thinking and if you were flying a jet with an exhaust pipe and then you fed in extra kero of course there would not be enough oxygen in there to get it to burn again. But if you have a gap in between the pipe and the fuselage (which i assume you should) which would have fresh air flowing through as an insulator could you make some sort of an intake into the pipe after the jet and before where you inject the kerosene? If the oxygen and fuel mixed in the heat of the exhaust also would it auto-ignite? Maybe this could give you a cool flame or afterburner effect or maybe even some extra thrust.