梯级引燃HCCI燃烧模式的提出和机理研究

本申请提出了“梯级引燃HCCI燃烧”的新概念：火花先点燃电热塞表面的高温稀薄混合气，形成原始火球，再引燃空间的“冷”稀薄混合气，最终触发HCCI燃烧。该模式集成火花助燃、电热塞助燃的优点，可在宽广的工况范围内实现对稀薄均质混合气燃烧过程的直接控制，优势有：①燃烧相位、燃烧速率独立控制，可实现燃烧过程优化；②有失火倾向的工况，可利用“火热塞”强制引燃并实现稳定燃烧，使工况向小负荷拓展；③有爆震倾向的工况，可通过降低进气温度，增大EGR率等间接手段，推迟HCCI的发生时刻，抑制放热速率，减少爆震倾向，使工况向大负荷拓展。拟采用三维数值模型仿真、解析解模型仿真、示功图分析、高速纹影摄影、色谱分析等手段，检验该燃烧模式的可行性，探究其产生机理和影响因素，确定工况范围，评估经济性、动力性和排放方面的潜力，制定控制参数策略。本研究主要意义在于：在完全继承“均质、低温”特征的前提下，解决了工况拓展难题

This application proposes a new concept of "cascade ignition HCCI combustion": the spark ignites the high temperature lean mixture of a glow plug surface, forms an original fireball, which ignition the space cold lean mixture, and finally triggers HCCI combustion. This combustion mode integrates the advantages of spark assisted HCCI (SACI) and glow plug assisted HCCI(GACI). It can realize the direct control of the combustion process of the lean homogeneous mixture in a wide working condition. The advantages are as follows: (1) Combustion timing and combustion rate are controlled independently to realize the combustion process optimization; ② at misfire tendency conditions, the use of "Spark-Glow Plug" forced ignition and achieve a stable combustion, so that the situation expand to small load; ③ at knock tendency conditions, by reducing the intake air temperature, increase EGR rate and other indirect ways to delay the HCCI combustion time and decrease the combustion rate, reduce the tendency of knock, so that the situation can be expanded to large load. By using three-dimensional digital model simulation, analytic solution model simulation, in-cylinder pressure analysis, high-speed image photography and chromatographic analysis, the feasibility of the combustion mode will be verified, and the mechanism and influencing factors will be studied, the working range and Economic, dynamical and emissions potential will be evaluated, and the control strategy will also be developed. The main significance of this research project is: To achieve the expanding of running condition, while completely inheriting the "homogeneous & low temperature" combustion characteristics.