Large-Eddy Simulation of turbulent, cavitating fuel flow inside a 9-hole Diesel injector including needle movement
Large-Eddy Simulation of turbulent, cavitating fuel flow inside a 9-hole Diesel injector including needle movement
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DOI：
10.1177/1468087416643901
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发表时间：
2017-03
影响因子：
2.5
通讯作者：
F. Örley;S. Hickel;S. Schmidt;N. Adams
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文献类型：
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作者：
F. Örley;S. Hickel;S. Schmidt;N. Adams
本文采用隐式大涡模拟方法研究了ISO4113柴油机在一个全喷油周期内共轨喷油器内的湍流多相流动。模拟包括从一维多域模拟获得的规定的针运动。喷射器的几何形状是由一个保守的切割单元为基础的浸没边界方法与子细胞的分辨率，已开发的应用程序中的空化液体流动的背景下。我们采用正压两相双流体模型，其中所有组分（即空气，液体柴油，气体柴油）由均匀混合物方法表示。空化模型是基于热力学平衡假设。所有相位的可压缩性使得能够完全解析湍流引起的压力波动力学。湍流流场分析表明，开闭阶段主要为小尺度湍流，而主喷射阶段则在喷针内部形成大涡结构并延伸到喷孔内部。在喷嘴孔的关闭阶段和囊孔区域的关闭之后，检测到空化结构的剧烈崩溃事件。与LES的结果与固定的喷射器针在不同的升降机位置的比较显示出良好的协议，大针升降机，而针的运动有显着的影响，在低针升降机的重要流动特征。
We investigate the turbulent multiphase flow inside a nine-hole common rail Diesel injector during a full injection cycle of ISO 4113 diesel fuel into air by implicit large-eddy simulation (LES). The simulation includes a prescribed needle movement obtained from a one-dimensional multi-domain simulation. The injector geometry is represented by a conservative cut-element-based immersed boundary method with subcell resolution, which has been developed for the application in the context of cavitating liquid flows. We employ a barotropic two-phase two-fluid model, where all components (i.e. air, liquid diesel, gaseous diesel) are represented by a homogenous mixture approach. The cavitation model is based on a thermodynamic equilibrium assumption. Compressibility of all phases enables full resolution of collapse-induced pressure wave dynamics. The analysis of the turbulent flow field reveals that the opening and closing phase are dominated by small-scale turbulence, while in the main injection phase large vortical structures are formed in the needle volume and reach into the nozzle holes. Violent collapse events of cavitation structures are detected during the closing phase in the nozzle holes and after closing in the sac hole region. A comparison with LES results with a fixed injector needle at different lift positions shows a good agreement for large needle lifts, while the needle movement has significant effects on important flow features at low needle lifts.