射流火焰淬熄及触发预混合气着火过程基础研究

采用预燃室结构的射流引燃燃烧方式具有拓展火花点火发动机稀燃范围、加快燃烧速度的能力以及主动控制预混合自燃燃烧相位的潜力，但目前其工作过程中的部分微观机理和宏观特性尚不十分明确。本项目通过高温高压定容弹内直接高速摄影、激光诱导荧光法和两色法可视化实验，同时配合化学反应动力学和计算流体力学数值模拟，对火焰淬熄过程发生的条件、淬熄产物、不同引燃模式产生的条件和特性进行研究。通过可视化实验和数值模拟，明确几何条件和热力学条件对典型淬熄产物的影响规律，探明射流火焰淬熄机理；分析不同的引燃模式和活性基成分、浓度对引燃不同温度、压力、浓度和燃料种类的预混合气燃烧过程的影响规律及不同燃烧模式产生的条件；分析触发预混合气多点同时自燃过程的热力学条件和参数敏感度；建立热和活性基共同作用下的预混合燃烧化学反应动力学简化模型并根据实验结果进行标定；丰富内燃机射流引燃燃烧基础理论以指导工程化研发。

Jet ignition combustion system with pre-chambers has the ability of extending lean burn limit, enhancing combustion velocity for spark-ignition engines. Meanwhile, it has the potential ability for actively controlling combustion phasing for premixed auto-ignition combustion. However, some of the microcosmic mechanisms and macroscopic characteristics of its processes are not well understood yet. In this project, with the help of optical experiments of direct high-speed video, PLIF and two-color method in a high-pressure high-temperature constant volume chamber, in collaboration with numerical simulation with chemical kinetics and computational fluid dynamics software, the following scientific issues related with that combustion system will be deeply investigated: geometric and thermo-dynamic conditions for flame quenching, quenched products, and conditions and characteristics for different ignition modes. The purpose of this project is to clarify the following issues: flame quenching mechanism; effect of geometric and thermodynamic conditions on typical quenched products; effect of ignition mode, active radical species and concentration on igniting premixture with different temperature, pressure, concentration and species of fuel; analysis of thermodynamic conditions and their sensitivity on triggering auto-ignition for premixed combustion; establishment and calibration of reduced chemical kinetics model with the co-effect of heat and active radicals for premixed combustion. All those efforts will enrich the fundamental combustion theories on jet ignition for internal combustion engines and offer useful instructions for engineering research and design.