An investigation at free-stream Mach numbers of 0.90 to 1.10 was made to determine (l) the jet boundaries and the flow fields around hot and cold jets, and (2) whether a cold-gas jet could adequately simulate the boundary and flow field of hot-gas jet. Schlieren photographs and static-pressure surveys were taken in the vicinity of a sonic jet which was operated over a range of jet pressure ratios of 1 to 6, specific heat ratios at the nozzle exit of 1.29 and 1.40 and jet temperatures up to 2600° R.nIt was found that the jets induced shock waves in the flow fields at sonic and supersonic stream velocities. Results indicated that the jet boundaries, shock waves, and pressure distributions in the flow field around a hot jet could be duplicated satisfactorily by a cold jet when the specific heat ratio and jet pressure ratio were matched.
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