An experimental investigation of chemically-reacting, gas-phase turbulent jets

Approved for public release; distribution is unlimited 13. ASTRACT (Mamum 200 wov*c A new high pressure combustion facility was built to investigate mixing in axisymmetric, tur-bulent jets exiting into quiescent reservoirs. The faciliti uses fluorine and nitric oxide, diluted with nitrogen, for chemical product formation that is accompanied by heat release. The average tem-perature was measured by a set of long, thin, resistance wire thermometers stretched across the jet centerline at 16 downstream locations from x/do = 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 num-ber independent up to Re = 150,000. Additionally, the measurements revealed a "mixing virtual origin, " defined as the far-field flame length extrapolated to 0 = 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 se