In the present study, detailed numerical simulations are performed to investigate the primary breakup of a gasoline surrogate jet under non-evaporative "Spray G" operating conditions. The Spray G injector and operating conditions, developed by the Engine Combustion Network (ECN), represent the early phase of spray-guided gasoline injection. To focus the computational resources on resolving the primary breakup, simplifications have been made on the injector geometry. The effect of the internal flow on the primary breakup is modeled by specifying a nonzero injection angle at the inlet. The nonzero injection angle results in an increase of the jet penetration speed and also a deflection of the liquid jet. A parametric study on the injection angle is performed, and the numerical results are compared to the experimental data to identify the injection angle that best represents the Spray G conditions. The nonzero injection angle introduces an azimuthally non-uniform velocity in the liquid jet, which in turn influences the instability development on the jet surfaces and also the deformation and breakup of the jet head. The asymmetric primary breakup dynamics eventually lead to an azimuthal variation of droplet size distributions. The number of droplets varies significantly with the azimuthal angle, but interestingly, the probability density functions (PDF) of droplet size for different azimuthal angles collapse to a self-similar profile. Analysis has also been conducted to estimate the percentage and statistics of the tiny droplets that are under resolved in the present simulation. The PDF of the azimuthal angle is also presented, which is also shown to exhibit a self-similar form that varies little over time. Finally, a model is developed to predict the droplet number as a function of droplet diameter, azimuthal angle where a droplet is located, and time.

中文翻译：

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非蒸发操作条件下汽油替代射流一次破裂的建模和详细数值模拟

在本研究中，进行了详细的数值模拟，以研究在非蒸发“喷雾 G”操作条件下汽油替代射流的初级分解。由发动机燃烧网络 (ECN) 开发的 Spray G 喷射器和操作条件代表了喷雾引导汽油喷射的早期阶段。为了将计算资源集中在解决初级破裂上，对喷射器几何结构进行了简化。通过指定入口处的非零注入角来模拟内部流动对一次破裂的影响。非零喷射角导致射流穿透速度的增加以及液体射流的偏转。对喷射角进行参数研究，并将数值结果与实验数据进行比较，以确定最能代表喷雾 G 条件的喷射角度。非零喷射角会在液体射流中引入方位角非均匀速度，进而影响射流表面的不稳定性发展以及射流头的变形和破碎。不对称的初级破碎动力学最终导致液滴尺寸分布的方位角变化。液滴的数量随方位角而显着变化，但有趣的是，不同方位角的液滴尺寸的概率密度函数 (PDF) 坍塌为自相似的轮廓。还进行了分析以估计当前模拟中未解决的微小液滴的百分比和统计数据。还提供了方位角的 PDF，它也显示出随时间变化很小的自相似形式。最后，开发了一个模型来预测作为液滴直径、液滴所在方位角和时间函数的液滴数量。