瞬态工况天然气发动机燃烧、排放和热力学性能在线检测与量化研究

推广天然气汽车是缓解我国能源危机、减少大气雾霾的有效途径之一。然而，在瞬态工况下天然气发动机容易出现失火、爆震等非正常燃烧现象，严重限制了天然气汽车的节能减排潜力和市场竞争力。本项目围绕影响天然气发动机瞬态性能的几个关键问题开展研究。采用前期自行开发的发动机瞬态性能在线检测技术，在道路循环工况下对天然气发动机工作过程进行在线、连续检测，在此基础上对其瞬态燃烧、排放和热力学性能进行诊断分析和量化研究：1）研究瞬态工况天然气发动机缸内燃烧和热力学过程的特征及其影响机理，得到量化关系；2）针对性能恶化的工作循环开展详细模拟，研究瞬态工况天然气发动机燃烧不稳定的诱因和影响机理；3）探索瞬态工况下天然气发动机主要有害排放物的生成机理。根据本项目研究结果，对天然气发动机瞬态运行或控制参数实时调整和瞬态标定策略提出改进方案。本项目的研究工作为改善天然气发动机瞬态性能提供理论依据和技术支撑。

The application of natural gas vehicle is one of the effective ways to alleviate the energy crisis and reduce the atmospheric haze in China. However, some abnormal combustion phenomena such as combustion deterioration and knock are more likely to occur in natural gas engine especially under transient conditions. Thus, both the potentials of energy saving and emission reduction and the market competitiveness of natural gas vehicle are limited severely. This project is intended to solve the issues which influence the transient performance of natural gas engine. By using the independently developed on-line detection technology for engine transient performance, the on-line and continuous detection for the transient operating process of natural gas engine will be carried out under vehicle driving cycles. On this basis, the diagnostic analysis and quantitative study will be conducted for the transient combustion, emission and thermodynamic performance of natural gas engine, which includes the following parts: 1) The influential mechanisms of in-cylinder combustion and thermodynamic processes of natural gas engine under transient conditions will be researched and the quantitative relations can be obtained. 2) The detailed numerical simulation on the working cycles in which performance deterioration exists will be carried out, and then the causes and influential mechanisms of combustion deterioration and combustion instability under transient conditions will be studied for natural gas engine. 3) The generation mechanisms of main harmful emissions of natural gas engine under transient conditions will be investigated. Based on the above research results, the suggestions for real-time adjusting the operating or control parameters and for improving the transient calibration strategy of natural gas engine will be proposed. The research work will provide the theoretical basis and technical support for improving the transient performance of natural gas engine.