长碳链脂肪酸甲酯喷雾及着火特性的基础研究

生物柴油简化替代物的合理选择对生物柴油氧化化学动力学机理开发和生物柴油发动机的工作优化有重要意义。直喷压燃式发动机的燃烧过程和排放物生成受到燃料的喷雾和着火过程的耦合影响，因此，对生物柴油替代物的选择和开发应当同时考虑其喷雾和着火特性。作为生物柴油重要组成成分，本项目针对长碳链的大分子脂肪酸甲酯，开展喷雾特性和着火延迟特性的基础研究。揭示变化喷射条件下的不同脂肪酸甲酯喷雾过程的油束宏观参数以及液滴微观特性；探究宽温度、压力、反应物当量比和混合气氧浓度范围内的不同脂肪酸甲酯气相反应的着火延迟时间尺度。最终阐明脂肪酸甲酯的喷射雾化特征以及着火延迟特性随分子碳链长度的变化规律以及影响机制，为生物柴油化学动力学简化替代物的开发以及机理验证提供试验依据，并将最终为生物柴油发动机的燃烧过程和排放物生成的控制和优化提供指导意义。

Reasonable choice of biodiesel surrogate is vital to the development of biodiesel oxidation chemical kinetics and the optimization of biodiesel engine operation. In direct injection compression ignition engine, combustion process and emissions formation are strongly influenced by fuel spray and auto-ignition processes; therefore, the spray and auto-ignition characteristics should be simultaneously considered in the selection and development of biodiesel surrogates. As important compositions in biodiesel fuels, the fundamental spray and ignition delay features of long carbon-chain, large-molecule fatty acid methyl esters are to be investigated in this project. The macroscopic and microscopic features of fuel spray and droplets of different fatty acid methyl esters will be revealed under various injection conditions; meanwhile, ignition delay time scale in gas phase reaction of different fatty acid methyl esters are also to be investigated within a broad range of temperature, pressure, fuel/charge equivalence ratio and charge oxygen concentration. This project aims to illustrate the effects and mechanisms of carbon chain length on spray and auto-ignition characteristics of fatty acid methyl esters, provide experimental database for biodiesel surrogates development and relevant chemical kinetics validation, and finally contribute to the control and optimization for the combustion process and emissions formation in biodiesel engines.