Coaxial atomizing sprays are used in industries from gas turbines to food processing. Spray dynamics depend heavily on the primary breakup (near-field) region. The near-field region is challenging to study because it contains thick liquid that is impenetrable to visible light. However, X-ray radiographs are capable of penetrating the dense liquid region, providing insight that is unavailable from visible light testing methods. This study modifies a method used in previous studies for determining the mass-averaged axial velocity from a narrow-angle, injection spray, into a method for studying the mass-averaged axial velocity from a wide-angle, constant spray. Experiments at the Advanced Photon Source at Argonne National Laboratory provided focused-beam X-ray radiographs along the spray. Results showed that the mass-averaged axial velocity along a coaxial spray increased linearly with axial distance from the nozzle for varying momentum ratios. The slope of the velocity-distance relation also increased linearly when plotted as a function of gas Reynolds number. Spray velocity is often considered for individual droplets or for the centerline, but not as a mass-averaged property. However, these results show that the mass-averaged axial velocity has predictable behavior in the near-field region for the conditions that were tested in this study.

中文翻译：

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通过聚焦X射线照相术确定喷雾轴向速度

同轴雾化喷雾用于从燃气轮机到食品加工的工业。喷雾动力学在很大程度上取决于主要的破裂（近场）区域。近场区域的研究具有挑战性，因为其中包含了无法透过可见光的浓稠液体。但是，X射线照片可以穿透稠密的液体区域，提供可见光测试方法无法提供的见解。本研究将先前研究中用于确定窄角喷射喷雾的质量平均轴向速度的方法修改为研究广角恒定喷雾的质量平均轴向速度的方法。阿贡国家实验室高级光子源的实验在喷雾过程中提供了聚焦束X射线照相。结果表明，在不同的动量比下，沿同轴喷雾的质量平均轴向速度随与喷嘴的轴向距离线性增加。当绘制为气体雷诺数的函数时，速度-距离关系的斜率也线性增加。通常针对单个液滴或中心线考虑喷雾速度，但不考虑其质量平均特性。但是，这些结果表明，对于本研究中测试的条件，质量平均轴向速度在近场区域中具有可预测的行为。但不是质量平均属性。但是，这些结果表明，对于本研究中测试的条件，质量平均轴向速度在近场区域中具有可预测的行为。但不是质量平均属性。但是，这些结果表明，对于本研究中测试的条件，质量平均轴向速度在近场区域中具有可预测的行为。