| 邱豪佶,黄云龙,何志霞,等.空气辅助喷射系统喷雾过程与雾化机制的数值模拟[J].内燃机工程,2025,46(3):27-38. |
| 空气辅助喷射系统喷雾过程与雾化机制的数值模拟 |
| Numerical Simulation on the Spray Process and Atomization Mechanism of an Air-Assisted Injection System |
| DOI：10.13949/j.cnki.nrjgc.2025.03.004 |
| 关键词:空气辅助喷射系统 欧拉–拉格朗日法 油膜分离与剥离 涡环 油膜质量 |
| Key Words:air-assisted injection system Eulerian-Lagrangian approach filmseparation and stripping vortex ring film mass |
| 基金项目:国家自然科学基金项目（52376113） |
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| 摘要点击次数: 15 |
| 全文下载次数: 2 |
| 摘要:为深入研究空气辅助喷射系统内外喷雾过程及气液相互作用引起的雾化机制，基于欧拉–拉格朗日法建立了包括完整空气辅助喷油器和定容环境体的数值模型，并提出了更精确且通用的喷雾模型设置。喷雾过程分为油气混合阶段和混合物喷射阶段。研究定性分析了油气混合阶段中燃油射流的表面破碎过程及液滴与壁面的反弹、飞溅和黏滞行为，明确混合腔设计在气液混合效率与进气稳定性中的关键作用。混合物喷射阶段的结果表明，定容环境体内液滴平均直径约为6 μm，拉瓦尔喷嘴出口处存在部分平均直径为20~30 μm的液滴。此外，进一步的雾化机制研究发现，出口区域还存在少量平均直径大于50 μm的液滴，且这些液滴来源于外壁面上油膜的分离。研究还揭示了涡环的形成机制：近场涡环由拉瓦尔喷嘴的几何形状决定，而远场涡环则由高速空气通过黏性力扰动静止环境氮气产生。最后，通过对空气辅助喷油器各壁面油膜质量变化的分析发现，上内壁面存在大量难以剥离的油膜，这可能导致冷起动过程中燃油积聚问题。 |
| Abstract:To deeply study the spray process and atomization mechanisms caused by the gas-liquid interaction in an air-assisted injection system， a numerical model was established based on the Eulerian-Lagrangian approach. The model includes a complete air-assisted injector and a constant-volume environment， with a more precise and universal spray model setup proposed. The spray process is divided into the fuel-air mixing stage and the mixture injection stage. The surface break-up process of the fuel jet in the fuel-air mixing stage， as well as the rebound， splash， and adhesion behaviors of droplets with the wall were qualitatively analyzed. The critical role of the mixing chamber design in the gas-liquid mixing efficiency and intake stability was clarified. The results from the mixture injection stage indicate that the average droplet diameter inside the constant-volume environment is about 6 μm， and droplets with an average diameter of 20~30 μm exist at the Laval nozzle exit. Furthermore， further research on the atomization mechanism reveals that a small number of droplets with diameters greater than 50 μm also exist in the exit region， and these droplets originate from the separation of the film on the outer wall. The formation mechanism of vortex rings was revealed in the study. The near-field vortex ring is determined by the geometry of the Laval nozzle， and the far-field vortex ring is generated by the high-speed air disturbing the stagnant nitrogen gas through viscous forces. Finally， an analysis of the film mass variation on each wall of the air-assisted injector indicates a large amount of film that is difficult to strip from the upper inner wall， which could lead to fuel accumulation issues during cold start. |
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