高稀释条件下微火源引燃低温燃烧机理及稳定性调控的基础研究

高稀释低温燃烧是实现高辛烷值燃料高效燃烧的重要途径，是汽油机燃烧的主要发展方向。目前面临的主要难题是：如何解决汽油机缸内受限复杂流场中高稀释条件下燃烧的不稳定性。为此，本申请提出 “微火源引燃燃烧”概念，通过向燃烧室内喷入高可燃性燃料，在流场作用下形成微火源在缸内的空间分布，进而引发缸内稳定的火焰传播和多点自燃。本申请拟从缸内湍流运动与微火源相互作用角度，深入研究高稀释条件下多尺度湍流对聚集型和离散型微火源的的形成、发展、淬灭、引燃及相互作用机理；研究增压、气门运动、燃料喷射策略对缸内流场、组分及温度分布的调控规律，探究微火源引燃燃烧稳定性的调控机制。研究结果对于理解受限条件下湍流对高稀释燃烧的作用机理，探索高稀释燃烧稳定性的调控方法，具有重要的理论价值；其理论体系的建立也会支持汽油机产业技术升级，具有重要的现实意义。

Diluted low temperature combustion is among the major principles in improving the overall efficiency of gasoline engines using high octane-number fuels. In order to overcome the limitations of combustion stability at highly diluted and turbulent conditions within the cylinder, one effective way is through the introduction of micro flame ignition in the means of direct injection of highly auto-ignitable fuels to provide a controllable source of high energy ignition to achieve stable ignition of the fuel-air mixture, optimized flame propagation and multiple auto-ignition. This research is intended to investigate the development of the micro flame ignition, in both the concentrated and scattered modes at highly diluted and turbulent conditions, including its formation, extinction, growth and movement and ignition of the surrounding fuel-air mixture. Aiming at a series of regulation strategies of stable diluted combustion, this research is also focused on the influences of control parameters, including the valve movements, sprays and elevated intake pressures, on the in-cylinder mixture and temperature distribution and the turbulent flow. The research is of theoretical importance in understanding the influences of turbulence on diluted combustion of gasoline engines and approaching regulation strategies of the combustion stability at highly diluted and turbulent conditions. The research also practically supports further development of gasoline engines towards higher overall efficiency by realizing controllable diluted combustion.