An Experimental Investigation of Chemically-Reacting, Gas-Phase Turbulent Jets
CALIFORNIA INST OF TECH PASADENA GRADUATE AERONAUTICAL LABS
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A new high pressure combustion facility was built to investigate mixing in axisymmetric, turbulent jets exiting into quiescent reservoirs. The facility uses fluorine and nitric oxide, diluted with nitrogen, for chemical product formation that is accompanied by heat release. The average temperature was measured by a set of long, thin, resistance wire thermometers stretched across the jet centerline at 16 downstream locations from xdo 30 to 240. The Reynolds number was varied through density, i.e., pressure, while the jet exit velocity and exit diameter were held constant. The main result of the work is that the flame length, as estimated from the temperature measurements, varies with changes in Reynolds number, suggesting that the mixing process is not Reynolds number independent up to Re 150,000. Additionally, the measurements revealed a mixing virtual origin, defined as the far-field flame length extrapolated to phi 0, that increases with increasing Re for Re 20,000 and then decreases with increasing Re for Re 20,000. The transition of the jet flow from a momentum-dominated to a buoyancy-dominated regime was identified in another set of experiments.