超声速气流中液体横向射流雾化的多尺度精细仿真

In a liquid-hydrocarbon-fuelled supersonic combustion ramjet (scramjet) engine, the atomization and mixing of liquid fuel in the supersonic air flow determines the engine ignition reliability and combustion performance. Since the liquid jet atomization process of transverse liquid jet in supersonic crossflow is very complicated, the physical mechanism and determining factors have not been well understood, requiring further research on this subject. This project aims to develop a multiscale Large Eddy Simulation (LES) algorithm for simulation of atomization and spray in supersonic flow, and investigate the physical mechanism of atomization and spray by LES. With the development of the adaptive mesh refinement, the details of the liquid jet breakup process will be resolved in an Eulerian framework using an interface tracking method. The droplet dispersion in the spray region will be solved in a Lagrangian framework using a particle tracking approach. The multiscale simulation of liquid jet atomization and spray in supersonic air crossflow will be carried out, and the simulation results will be compared with the experimental measurements to validate the developed models and numerical methods. For the typical flame-holding cavity configuration of scramjet, detailed LES is used to investigate the influence parameters and physical mechanism of transverse liquid jet atomization in supersonic flow, elucidate the physical mechanism of spray mixing in cavity shear layer, and develop the models of spray distribution inside the cavity and outside the cavity, providing significant data and theoretical support in the design of the fuel injection and mixing scheme in scramjet engines.

在液体碳氢燃料超燃冲压发动机中，液体燃料在超声速气流中的雾化混合决定着发动机点火可靠性和燃烧性能。由于超声速气流中液体横向射流雾化过程极为复杂，物理机理和影响因素尚未明确，有待进一步的深入研究。本项目旨在发展一种用于超声速气流中雾化多尺度仿真的大涡模拟方法，借助精细仿真研究液体横向射流雾化喷雾机理。拟结合自适应网格加密技术，在欧拉框架下采用界面跟踪方法对液体射流变形破碎过程进行精细求解。在拉格朗日框架下采用颗粒轨道模型对喷雾区的液雾扩散过程进行精确求解。本项目拟对超声速气流中液体横向射流雾化喷雾过程开展三维多尺度大涡模拟，通过与试验结果对比验证所发展的数学模型和计算方法。针对超燃冲压发动机典型的稳焰凹腔构型，借助精细数值仿真揭示超声速气流中液体横向射流雾化的物理机理和影响因素，明晰凹腔剪切层对液雾的卷吸机制，掌握凹腔内和凹腔外的喷雾分布规律，为燃料喷注混合设计提供重要的数据支撑和理论基础。

以超过五倍声速速度飞行的高超声速飞行器在国防安全领域有着颠覆性的应用，因此各军事强国将高超声速飞行器的发展列为“最高技术优先级”。超燃冲压发动机具有高比冲，是大气层内高超声速飞行器的最佳推进系统。在液体碳氢燃料超燃冲压发动机中，液体燃料在超声速气流中的雾化混合决定着发动机点火可靠性和燃烧性能。超声速气流中液体横向射流雾化过程极为复杂，导致理论分析和试验观测非常困难。本项目发展了一种用于超声速气流中雾化多尺度仿真的大涡模拟方法，借助精细仿真研究了液体横向射流雾化喷雾机理。在欧拉框架下采用界面跟踪方法对液体射流变形破碎过程进行精细求解。在拉格朗日框架下采用颗粒轨道模型对喷雾区的液雾扩散过程进行精确求解。本项目对超声速气流中液体横向射流雾化喷雾过程开展了三维多尺度大涡模拟，仿真结果与试验结果吻合，从而验证了所发展的数学模型和计算方法。针对超燃冲压发动机典型的稳焰凹腔构型，借助精细数值仿真揭示了超声速气流中液体横向射流雾化的物理机理和影响因素，明晰凹腔剪切层对液雾的卷吸机制。借助数值仿真进一步研究了液体燃料射流喷注角度、喷嘴形状、物理斜坡、气动斜坡及凹腔对射流穿透深度和雾化特性的影响，掌握了喷雾分布规律，为燃料喷注混合设计提供了重要的数据支撑和理论基础。