基于RCCI燃烧的加氢催化生物柴油/汽油同轴喷射活性分层控制机理

RCCI（reactivity controlled compression ignition）is the most effective combustion mode till now to achieve higher engine thermal efficiency and ultra-low NOx and PM emissions. However, RCCI combustion is facing the biggest challenges of the control of the time and magnitude of HRR (heat release rate), some key fundamental scientific issues such as the reactivity stratified control in combustion under different engine loads. Based on the researches on combustion of NG/Diesel dual fuel coaxial injection mode, an extend RCCI mode is proposed by coaxial injection with high cetane biodiesel and gasoline. This project focuses on the research of ignition and combustion characteristics of such co-injection dual fuel reactivity stratified controlled RCCI. Optical measurements of mixing and combustion of gasoline and second-generation biodiesel co-injection mode in a constant volume bomb will be made to obtain the ignition delay and flame propagation characteristics under different reactivity control. Optical diagnostic of RCCI by such dual fuel co-injection mode in high compression ratio an optical engine to reveal the performance of ignition and HRR as well as soot formation, especially under turbulent. Simulation of RCCI combustion based on the reaction mechanism of gasoline and second-generation will be realized to get the Combustion characteristics and reactivity-controlled strategy. Theoretical supports are provided for this New method for extending RCCI combustion mode based on the above researches.

反应活性控制压燃（RCCI）方式是提高发动机热效率和实现发动机超低排放的最有效途径，然而燃烧放热速率及相位的有效控制是RCCI方式面临的最大挑战，不同燃烧工况下的燃料活性分层控制等关键科学问题亟待解决。在前期对天然气/柴油同轴喷射燃烧研究基础上，结合加氢催化生物柴油的高十六烷值特性，本项目提出采用汽油与加氢催化生物柴油同轴喷射方式实现RCCI活性分层燃烧控制的新方法。针对定容弹内不同条件下加氢催化生物柴油/汽油的同轴喷射混合燃烧过程进行光学测试，获取不同活性分层控制的着火延迟与火焰传播特性；提出基于PLIF的双示踪双波长法，开展光学发动机内双燃料同轴喷射RCCI燃烧过程光学诊断，揭示燃料活性分层控制的着火特征与燃烧放热规律；引入耦合喷嘴内流的初次雾化模型实现RCCI燃烧过程准确模拟；获得多因素作用的同轴喷射方式下燃料活性分层控制燃烧规律与策略，为拓展RCCI燃烧模式提供一种新的方法。

反应活性控制压燃（RCCI）方式是提高发动机热效率和实现超低排放的最有效途径，但燃烧放热率及燃烧相位的有效控制是其面临的最大挑战。基于燃料设计理念，本项目提出了汽油/加氢催化生物柴油双燃料RCCI燃烧特性研究，揭示汽油/加氢催化生物柴油活性分层控制着火燃烧机理，获得汽油/加氢催化生物柴油高效稳定燃烧控制理论。本项目首先在定容燃烧弹上开展了汽油/加氢催化生物柴油喷雾、着火、燃烧及碳烟生成特性光学诊断研究，获得了准稳态条件下汽油/加氢催化生物柴油着火燃烧影响规律；随后在一台高压缩比光学发动机上开展了RCCI模式在不同喷油策略下的着火、燃烧特性光学诊断研究，获得了RCCI模式下着火位置、着火延迟期、燃烧持续期、燃烧相位、火焰发展变化，揭示了不同燃料比例、不同喷射策略下对RCCI燃烧的影响机制；最后，构建了汽油/加氢催化生物柴油的燃烧反应动力学机理，获得了RCCI多维燃烧模型，获得了低负荷稳定燃烧调控理论。