Spray characterization for engine combustion network Spray G injector using high-fidelity simulation with detailed injector geometry
Spray characterization for engine combustion network Spray G injector using high-fidelity simulation with detailed injector geometry
复制标题
发动机燃烧网络的喷雾表征 Spray G 喷油器使用具有详细喷油器几何形状的高保真仿真
DOI：
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发表时间：
2020
影响因子：
2.5
通讯作者：
S. Som
中科院分区：
文献类型：
--
作者：
Zongyu Yue;M. Battistoni;S. Som
本文介绍了发动机燃烧网络喷雾G的计算流体动力学研究，重点是喷射开始期间喷雾的瞬态特性和来自制造过程的喷嘴几何细节的影响。采用大涡模拟方法结合流体体积法对高速湍流两相流进行数值模拟。采用动针边界条件精确捕捉内流边界条件。在阿贡国家实验室的高级光子源中，使用X射线断层成像以微米级分辨率测量喷射器几何形状，提供详细的加工公差和制造缺陷以及真实的粗糙表面。为了进行比较，在模拟中还使用了标称几何形状和修改后的几何形状，该几何形状包含测量的大尺度几何特征，但没有表面细节。分析了喷雾特性，如质量流量、喷射速度和索特平均直径。使用不同的喷嘴几何形状，这主要是由于现实的表面光洁度和制造缺陷的喷射速度，喷雾形态，和主要的破碎机制方面的显着不同的喷雾特性进行了预测。测量的高分辨率几何预测较低的喷射速度，更广泛的传播喷雾，和一个整体较慢的破碎率与明显的喷嘴尖端润湿相比，理想的光滑喷嘴边界。这一结果意味着，喷油器的制造细节，这通常是被忽略的燃油喷射研究，喷雾发展过程中有显着的影响，并应考虑到设计优化。
This article presents a computational fluid dynamics study of the engine combustion network Spray G, focusing on the transient characteristics of the spray during the start of injection and the impacts of nozzle geometry details derived from the manufacturing process. The large-eddy-simulation method, coupled with the volume-of-fluid method, was used to model the high-speed turbulent two-phase flow. A moving-needle boundary condition was applied to capture the internal flow boundary condition accurately. The injector geometry was measured with micron-level resolution using X-ray tomographic imaging at the Advanced Photon Source at Argonne National Laboratory, providing detailed machining tolerance and defects from manufacturing and a realistic rough surface. For comparison, a nominal geometry and a modified geometry incorporating measured large-scale geometric features but no surface details were also used in the simulations. Spray characteristics such as mass flow rate, injection velocity, and Sauter mean diameter were analyzed. Significantly distinct spray characteristics in terms of injection velocity, spray morphology, and primary breakup mechanism were predicted using different nozzle geometries, which is mainly attributable to the realistic surface finish and manufacturing defects. The measured high-resolution geometry predicts a lower injection velocity, a wider-spreading spray, and an overall slower breakup rate with evident injector tip wetting compared to the ideally smooth nozzle boundary. This result implies that the manufacturing details of the injector, which are usually ignored in fuel injection studies, have a significant impact on the spray development process and should be taken into account for design optimization.