Abstract
Measurement of the ambient air velocity distributions in and around a D. I. gasoline engine spray was made by combining the laser induced fluorescence technique and the particle image velocimetry (LIF-PIV) technique. The rhodamine and water solution was injected into ambient air by a swirl-type injector to disperse the fine fluorescent liquid particles as tracers for the ambient air motion. A fuel spray was injected into the fluorescent tracer cloud by the D. I. gasoline injector and was illuminated by an Nd : YAG laser light sheet (532nm). The scattered lights from the spray droplets and tracers were cut off by a high-pass filter (>580nm). As the rhodamine absorbs the light of the laser, it fluoresces at a light whose wavelength greater than 600nm. The fluorescence from the tracers, were transmitted through the high-pass filter and the images were captured by using a high-resolution digital CCD camera. The tracer images were analyzed by double frame cross-correlation PIV and the ambient air velocity distribution could be obtained. The ambient air velocity distribution by the rhodamine tracer was compared with the ambient air velocity distribution by the microballoon tracer to validate accuracy of the tests the velocity distribution of the rhodamine tracer was almost the same as that of the microballoon tracer around the spray. Then, this technique was applied to a D. I. gasoline spray. As shown in Fig. A-(a), the ambient air flows up around the spray and enters into the tail of the spray. As shown in Figure A-(b) shows the comparison of the velocities between the spray and ambient air.
