ENHANCEMENT OF MIXING IN HIGH-SPEED HEATED JETS USING A COUNTERFLOWING NOZZLE

An experimental study was conducted to examine the effect of annular c ounterflow on the mixing of high-speed subsonic jets and slightly unde rexpanded supersonic jets. Suction was applied to a collar placed conc entrically about a converging nozzle to create a counterflowing stream around the jet periphery. The primary jet was operated at exit Mach n umbers between 0.4 and 1.2, for stagnation temperatures from 20 to 400 -degrees-C. The results show that moderate levels of counterflow can b e used to enhance the mixing between the jet and surrounding fluid. Fu rthermore, the counterflow control technique becomes more effective as the jet temperature is increased.