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.

该项目的总体目标是了解决定内燃机燃油喷射喷嘴波动的机制。为此，将进行包括直接数值模拟（DNS）在内的调查。这些将包括空化以及喷射器内部流动中的相变过程。为了评估燃料喷射的循环变化，将首先在压力室中检查喷射几何形状、液滴尺寸和速度以及周围的气体速度场。此外，还将详细研究循环内燃机工况下的进气流量、燃油喷射过程、一次燃油分解和二次分解的第一阶段。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相互作用的不断变化的循环变化、基本操作参数对喷射射流和燃料雾化结构的影响以及它们对缸内流动特性的影响将使用混合 VOF-拉格朗日耦合进行分析。此类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。将定义喷射-蒸发-混合物-点火-火焰传播相互作用的循环变化中涉及的具体操作参数。由喷雾雾化产生的液滴特性（尺寸、速度等）的信息将作为流入条件提供，这反过来又会在燃烧室中传递周围的流场和温度场。基于喷雾可视化数据，我们将评估近喷嘴区域的模拟是否也可以在内燃机条件下提供准确的预测，该模拟将首先根据恒定体积 ECN 配置的数据进行详细验证。依靠对进气流、喷射过程、初级射流崩解和二次破碎第一阶段与缸内流动之间的相互作用的分析，将进行基于逆向分析的协作研究，以识别喷射崩解这些特性是造成上述缸内流量的循环变化的原因。在这方面，连续注射的效果也有待分析。所需的实验数据和所选循环的边界条件。有关喷雾雾化模型对循环变化敏感性的研究结果将在下一个应用周期内进行整合，以分析循环变化对爆震燃烧的影响。