Numerical investigation of unsteady effects on the structure of IC-engine injection jets

内燃机喷射喷嘴结构非定常影响的数值研究

• 批准号: 423137312
• 负责人: Professor Dr. Amsini Sadiki
• 金额: --
• 依托单位: Fachgebiet Energie- und Kraftwerkstechnik
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/423137312?language=en
• 关键词: Numerical; investigation; unsteady; effects; structure

The global objective of this project is to understand the mechanisms that determine thefluctuations of IC engine fuel injection jets. For this purpose, investigations including directnumerical simulations (DNS) will be carried out. These will include cavitation along with phase change processes in the injector internal flow. To assess the cyclic variations of the fuel injection, the jet geometry, droplet sizes and velocities as well as the surrounding gas velocity field will be first examined in a pressure chamber. In addition, the intake flow, fuel injection process, primary fuel disintegration and the first phase of secondary breakup will beinvestigated in detail under cyclic IC engine conditions. To retrieve the impact of these processes and to quantify the evolving cycle-to-cycle variations of the interaction between evaporation, mixture, ignition and flame propagation, the influence of the essential operating parameters on the structure of injection jet and fuel atomization as well as their effect on the in-cylinder flow properties will be analyzed using a hybrid VOF-Lagrange coupling. Such an analysis will be performed for different cavitation numbers, fuel properties (single- or multi-component fuels, such as iso-octane, mixtures or biofuels), injection pressures and realistic injector geometries. The specific operating parameters which are involved in the cycle-to-cycle variation of the interaction injection-evaporation-mixture-ignition-flame-propagation will be defined. The information on droplet properties (size, velocity, etc.) resulting from the spray atomization will be provided as inflow conditions, which will, in turn, deliver surrounding flow and temperature fields in the combustion chamber. Based on the spray visualization data, we will evaluate whether simulations of the near nozzle region, which will be first validated in detail based on data from a constant volume ECN configuration, can alsoprovide accurate predictions under IC engine conditions. Relying on the analysis of the interaction between the inlet flow, injection process, primary jet disintegration and the first phase of secondary breakup with the in-cylinder flow, a collaborative study - based on backward analysis will be performed in order to identify the spray disintegration properties that are responsible for the aforementioned cycle-to-cycle variations in the in-cylinder flow. In this respect, effects of successive injections are also to be analyzed. The required experimental data and the boundary conditions for the selected cycle. The findings regarding spray atomization modeling with respect to sensitivities to cycle-to-cycle variations will beintegrated within the next application period to analyze the influence of cyclic variations on knocking combustion.

该项目的全球目标是了解决定内燃机燃油喷射波动的机制。为此，将进行包括直接数值模拟（DNS）在内的调查。这些将包括空化沿着喷射器内部流中的相变过程。为了评估燃料喷射的周期性变化，首先将在压力室中检查射流几何形状、液滴尺寸和速度以及周围气体速度场。此外，本文还对循环内燃机的进气流动、喷油过程、燃料一次破碎和二次破碎的第一阶段进行了详细的研究。为了检索这些过程的影响，并量化蒸发，混合，点火和火焰传播之间的相互作用的不断发展的循环到循环的变化，喷射射流和燃料雾化的结构上的基本操作参数的影响，以及它们对缸内流动特性的影响将使用混合VOF-Lagrange耦合进行分析。这种分析将针对不同的空化数、燃料特性（单组分或多组分燃料，例如异辛烷、混合物或生物燃料）、喷射压力和实际喷射器几何形状进行。将定义涉及喷射-蒸发-混合物-点火-火焰传播相互作用的循环间变化的具体操作参数。关于液滴特性（尺寸、速度等）的信息由喷雾雾化产生的温度场将被提供为流入条件，这又将传递燃烧室中的周围流场和温度场。根据喷雾可视化数据，我们将评估是否模拟的近喷嘴区域，这将首先详细验证的基础上，从一个恒定的体积ECN配置的数据，也可以提供准确的预测在内燃机条件下。依靠对进气流、喷射过程、主射流解体和第一阶段二次解体与缸内流之间相互作用的分析，将进行基于后向分析的协作研究，以确定导致缸内流中上述循环至循环变化的喷雾解体特性。在这方面，也要分析连续注射的效果。所需的实验数据和所选循环的边界条件。在下一个应用周期内，将结合喷雾雾化模型对循环变化敏感性的研究结果，分析循环变化对爆震燃烧的影响。