船用低速双燃料发动机重油模型燃料超临界高压微喷引燃多场耦合调控机制研究

预燃室内高压微喷雾化燃烧组织是改善低压天然气喷射模式低速双燃料发动机性能的重要途径。引燃油喷射时缸内或预燃室内的温度压力已超过空气和燃油的临界温度和临界压力，缸内或预燃室内燃油雾化过程已不再是传统的液滴破碎蒸发过程，而是超临界环境下燃料流体的瞬变多相流问题，进而影响燃烧组织与整机性能。本项目针对船用重油碳链长、组分复杂、杂质多等理化特征，以及船用低速机高密度、强涡流的工况条件，获取重油关键组分宽温度宽压力范围下的着火与氧化历程，构建准确且可适应超临界条件的重油模型燃料，揭示不同活性氛围下重油模型燃料超临界高压微喷雾化引燃火焰调控机制，阐明超临界条件下，高压微喷雾化、湍流强度、反应活性氛围三者对引燃火焰发展和预混天然气燃烧影响的耦合作用关系，探索双燃料低速机新型燃烧模式发动机运行边界条件下超临界高压微喷雾化引燃的优化调控方法，为双燃料低速机高效清洁燃烧组织提供基础数据和理论依据。

The strategy of high-pressure micro-pilot spray and combustion in the pre-chamber is an important way to improve the performance of low-speed dual-fuel marine engine. During pilot fuel injection, the average temperature in the cylinder and pre-chamber has exceeded the critical temperature and pressure of fuel mixture. The fuel atomization process in the cylinder and pre-chamber is no longer a traditional droplet crushing and evaporation process, but a transient multiphase flow problem of fuel fluid in a supercritical environment, which in turn affects the combustion organization and overall performance. This project intends to reveal the ignition and oxidation properties of the key components of heavy fuel oil in a wide range of temperature and pressure. Key physical and chemical characteristics of the heavy fuel oil have been focused on, including carbon chain length, fuel components, etc. Besides, the high-density and strong vortex conditions of the low-speed marine engine have also been taken into consideration. Therefore, surrogate for heavy fuel oil can be developed, which is capable of studying the effects of supercritical pressure on spray and combustion, and revealing the mechanism of high-pressure micro-pilot spray combustion in confined spaces under supercritical conditions. The coupling effects of high-pressure micro-pilot spray, turbulence intensity and reactive atmosphere on the development of combustion and flame under supercritical conditions will be clarified. The strategy for the optimization of high-pressure micro-pilot spray and combustion will be explored under certain engine condition boundary. The results of this research could provide significant data and theoretical basis for the development of high-efficiency clean combustion organization and key combustion technology in low-speed dual-fuel engines.