GASOLINE SPRAYS IN UNIFORM CROSSFLOW

Le résumé fourni par la source

Sprays from a gasoline direct injector into a chamber at atmospheric pressure with an injection duration of 3.2 ms and a uniform 11 m/s crossflow have been visualized by a high-resolution CCD camera, and the velocity and droplet characteristics measured with a phase Doppler anemometer. The images show that smaller droplets were displaced in the direction of the crossflow by 5.6, 6.9, and 7.6 mm for injection pressures of 30, 50, and 80 bar, respectively, 1.5 ms after the start of injection. These values increased with time. The crossflow decreased the penetration on the incident side of the cone spray and caused a small increase on the lee side. The local measurements confirm the displacement of droplets of diameter and velocity less than around 27 μm and 22 m/s, respectively, by the crossflow at an injection pressure of 30 bar and the corresponding values at 80 bar were 20 μm and 25 m/s. The radial distributions of droplet mean velocity showed a clear shift of mean velocity profile on the order of 15 mm in the direction of crossflow for 30 and 80 bar injection pressures at axial locations 60 and 80 mm, respectively. The results are directly relevant to gasoline engines with combinations of swirl and tumble and early injection. The spray will be shorter with the higher cylinder pressures of late injection and the ratio of cross-flow to spray momentum will be higher so that the effects will be larger.

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