Combustion of Fuel Spray Injected into High Speed Airstream

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The atomization process of a liquid jet in a high speed airstream was investigated by using the window tunnel whose maximum airstream velocity was 140 m/s(Mach number is 0.4). The liquid(water)was injected across the airstream from the injector with an niner diameter of 0.9 mm. The shape of the spray was measured by taking photograph. Sauter mean diameter was measured by a drop size analyzer based on tlie Fraunhofer diffraction theory. Spatial distribution of a spray was measured by a sampling method. Deformation and atomization processes of a liquid column observed by means of laser sheet tomography. Calculation of spatial distribution of injected liquid, drop diameter and drop trajectory. The drop was calculated based on the RayleighTaylor breakup model. When the air velocity was high, the holizontal section of the liquid column was bowed by the high speed airstream and small drops were produced at both sides of the bowed column. A cavity with no drops was found behind the liquid column. When the airstream velocity and the injection velocity were low, the liquid column wound across the airstream, and then relatively large drops were produced. The calculation showed that the drop diameter decreased rapidly along the outer line of the spray, but it scarcely decreased along the inner line of the spray. The outer and inner lines agreed with the trajectories of a drops whose initial diameter were 900 mum and 10 mum, respectively. The spatial distribution of the calculated drop diameter agreed with the spatial distribution of the measured Sauter mean diameter away from the injector. Disagreement of the drop diameter near the injector between the calculation and the measurement suggested that the breakup model of the liquid column had to be incorpolated into the calcultion.