To progress toward the high efficiency and low emission aviation engine technology, it is mandatory to understand the complex phenomena including kerosene spray atomization, evaporation, turbulent mixing and combustion in the engine combustor. Nowadays with the rapid growth of computational capacity over the world, large-eddy simulation (LES) performs a more and more important role in understanding the complex multi-phase combustion process of kerosene fuels in aviation engine configuration. In the present work, LES is employed to investigate a swirling kerosene spray jet flame in a model combustor, which has been studied experimentally. The turbulent combustion is modeled by the flamelet generated manifold (FGM) approach with a 3-component surrogate kerosene skeletal mechanism. The averaged gas velocity and temperature predicted by LES generally agrees well with the experimental measurements. Local extinction is observed at the inner shear layer of the swirling spray flame, due to droplet-turbulence-flame interactions. A parametric study with 11 cases is then performed to investigate the effects of inlet swirl/Reynolds number and fuel heating value on the kerosene flame. As the swirl number increases, the enhanced turbulent mixing between kerosene fuel and air facilitates the combustion process, but combustion instabilities may occur if the swirl number is too high. A higher Reynolds number can promote the turbulent combustion via a stronger recirculation zone, but it also has strong dilution effects on the combustion field. Variations in the fuel heating value directly impact the temperature field, but the flow field, major species concentrations and droplet phase statistics are only slightly affected. These LES results give clues to achieve optimal combustion performance in realistic aviation engine configurations via better arrangements of fuel and air injections.

中文翻译：

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入口涡流/雷诺数和燃料热值对湍流煤油喷射火焰影响的大涡模拟研究

为了向高效率、低排放航空发动机技术迈进，必须了解发动机燃烧室中煤油喷雾雾化、蒸发、湍流混合和燃烧等复杂现象。如今，随着全球计算能力的快速增长，大涡模拟（LES）在理解航空发动机配置中煤油燃料的复杂多相燃烧过程中发挥着越来越重要的作用。在目前的工作中，LES 用于研究模型燃烧器中的旋转煤油喷射火焰，并已进行了实验研究。湍流燃烧通过火焰生成歧管 (FGM) 方法和 3 组件替代煤油骨架机制进行建模。 LES 预测的平均气体速度和温度总体上与实验测量结果吻合良好。由于液滴-湍流-火焰相互作用，在旋转喷雾火焰的内剪切层观察到局部消光。然后通过11个案例进行参数研究，研究入口涡流/雷诺数和燃料热值对煤油火焰的影响。随着旋流数的增加，煤油燃料和空气之间的湍流混合增强，有利于燃烧过程，但如果旋流数太高，可能会出现燃烧不稳定。较高的雷诺数可以通过较强的再循环区促进湍流燃烧，但对燃烧场也有较强的稀释作用。燃料热值的变化直接影响温度场，但流场、主要物质浓度和液滴相统计仅受到轻微影响。这些 LES 结果为通过更好的燃油和空气喷射安排在实际航空发动机配置中实现最佳燃烧性能提供了线索。