Combustion of Fuel Spray Injected into High Speed Airstream

采用最大气流速度为140m/S(马赫数为0.4)的窗口风洞，对高速气流中液体射流的雾化过程进行了研究。液体(水)从直径为0.9 mm的注射器沿气流注入。通过拍照测量了喷雾的形状。索特平均直径由基于夫琅和费衍射理论的液滴粒度分析仪测量。采用抽样法测量了喷雾的空间分布。用激光薄片层析技术观察液柱的变形和雾化过程。计算了注入液体的空间分布、液滴直径和液滴轨迹。降幅是根据RayleighTaylor分手模型计算的。当风速较高时，液柱的水平截面在高速气流的作用下发生弯曲，在弯曲的柱体两侧产生小液滴。在液柱后面发现了一个没有液滴的空腔。当气流速度和喷射速度较低时，液柱缠绕在气流中，产生较大的液滴。计算结果表明，液滴直径沿喷雾外线迅速减小，而沿喷雾内线几乎没有减小。外线和内线与初始直径分别为900微米和10微米的液滴的轨迹一致。计算的液滴直径的空间分布与远离喷嘴的索特尔平均直径的空间分布相吻合。喷嘴附近液滴直径的计算值与实测值不一致，说明计算中必须考虑液柱的破碎模型。

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.