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Experimental Results on a Gaseous Jet Into a Turbulent Air Crossflow: Effect of the Shape of Injector Inlet on Fuel/Air Mixing

This paper presents experimental results on a gaseous jet into an air crossflow. A plain-orifice type injectors are employed for this research. It is mounted flush with a bottom wall of a test rig with a rectangular cross-section. The main emphasis is to investigate the effect of aspect ratio of the injector on fuel/air mixing. Injector diameter is fixed at 1.59 mm and two injectors with the orifice aspect ratio (1/d) of 1 and 5 are chosen for the purpose. Velocity ratios of a fuel jet to an air crossflow, Vj/Va, are chosen as 3, 5 and 7, and the mean crossflow velocity ranges 2 to 40 m/sec, which results in a wide range of Reynolds numbers for the gaseous jet encompassing laminar to turbulent flow. Acetone planar laser-induced fluorescence measurement is used for the representation of fuel concentration. The decay rate of scalar concentration, fuel jet penetration and cross-sectional distributions of the fuel plume are determined for the two injectors. First, the effect of the aspect ratio of the injector in quiescent surroundings is considerable at low jet velocities, i.e. laminar jet flow, but not at jet velocities corresponding to turbulent jet flow. Second, the influence of the aspect ratio of the injector in the air crossflow is similar to that observed in the free jet. At the laminar jet condition, the difference in the turbulent intensity produced by the aspect ratio of the injector changes the jet core characteristics of each injector and causes a difference in jet penetration. However, in the turbulent jet flow, it is found that the effect of the aspect ratio on the jet penetration is insignificant. Third, for the concentration decay, the concentration decreases with the slope of −7/9 in the laminar jet flow and the concentration decreases with the slope of −5/9 in the turbulent jet flow.