This paper presents the details of a Computational Fluid Dynamics methodology to accurately model the process of mixture preparation in modern Gasoline Direct Injection engines, with particular emphasis on liquid film as one of the main causes of Particulate Matter formation. The proposed modelling protocol, centred on the Bai-Onera approach of droplets-wall interaction and on multi-component surrogate fuel blend models, is validated against relevant published data and then applied to a modern small-capacity GDI engine, featuring centrally-mounted spray-guided injection system. The work covers a range of part-load, stoichiometric and theoretically-homogeneous operating conditions, for which experimental engine data and engine-out Particle Number measurements were available. The results, based on the parametric variation of start of injection timing and injection pressure, demonstrate how both fuel mal-distribution and liquid film retained at spark timing, may contribute to PN emissions, whilst their relative importance vary depending on operating conditions and engine control strategy. Control of PN emissions and compliance with future, more stringent regulations remain large challenges for the engine industry. Renewed and disruptive approaches, which also consider the sustainability of the sector, appear to be essential. This work, developed using Siemens Simcenter CFD software as part of the Ford-led APC6 DYNAMO project, aims to contribute to the development of a reliable and cost-effective digital toolset, which supports engine development and diagnostics through a more fundamental assessment of engine operation and emissions formation.

本文详细介绍了计算流体动力学方法的详细信息，以准确模拟现代汽油直喷发动机中的混合物制备过程，特别强调液膜是颗粒物形成的主要原因之一。所提出的建模协议以液滴-壁相互作用的 Bai-Onera 方法和多组分替代燃料混合模型为中心，根据相关的已发布数据进行验证，然后应用于具有中央安装喷雾的现代小容量 GDI 发动机-引导注射系统。这项工作涵盖了一系列部分负载、化学计量和理论上均质的操作条件，对于这些操作条件，可以获得实验发动机数据和发动机输出粒子数测量值。结果，基于喷射正时和喷射压力的参数变化，演示燃料分布不均和在火花正时保留的液膜如何导致 PN 排放，而它们的相对重要性因工况和发动机控制策略而异。控制 PN 排放和遵守未来更严格的法规仍然是发动机行业面临的巨大挑战。更新和破坏性的方法，也考虑到该部门的可持续性，似乎是必不可少的。这项工作是使用西门子 Simcenter CFD 软件开发的，作为福特领导的 APC6 DYNAMO 项目的一部分，旨在为开发可靠且具有成本效益的数字工具集做出贡献，