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为了突破柴油机“NOx-Soot”折中曲线的束缚,提出基于O2/CO2环境的柴油机燃烧新模式,运用AVL-FIRE软件对发动机缸内压力、温度场分布及整机动力性能进行数值模拟,分析不同参数对柴油机燃烧特性的影响,从而获得最佳的O2/CO2摩尔百分比,最后在光学发动机上对典型曲轴转角时刻缸内燃烧过程进行了可视化研究。仿真结果表明,当供油提前角不变时,O2低于50%时,缸内柴油无法着火燃烧;O2为65%、CO2为35%是该方案中的最佳参数组合;当改变供油提前角时,O2为50%、CO2为50%是该方案中的最佳参数组合。光学可视化试验表明,O2/CO2环境的最大压力升高率时刻、最大放热率时刻缸内平均温度均低于正常空气时,而最大爆发压力时刻的缸内平均温度略高于正常空气时;和正常空气相比,O2/CO2环境的主燃烧期扩散燃烧速率提高约37.6%。
In order to break the shackles of the “NOx-Soot” compromise curve of diesel engine, a new diesel combustion mode based on O2 / CO2 environment is proposed. AVL-FIRE software is used to simulate the pressure and temperature distribution in the engine cylinder and the whole dynamic performance The influence of different parameters on the combustion characteristics of the diesel engine was analyzed to obtain the optimal molar percentage of O2 / CO2. Finally, the visualization of the combustion process in a cylinder with a typical crank angle was carried out on an optical engine. The simulation results show that the cylinder diesel can not ignite when O2 is lower than 50% when the advance angle of oil supply is constant. O2 is 65% and CO2 is 35%, which is the best combination of parameters in the scheme. When changing the oil supply In the advance angle, O2 is 50% and CO2 is 50%, which is the best combination of parameters in this solution. The optical visualization test showed that the average cylinder temperature in the maximum pressure rise time and the maximum heat release time in O2 / CO2 environment are lower than those in normal air, while the average cylinder temperature in the maximum explosion pressure time is slightly higher than that in normal air. Compared with normal air, the diffusion combustion rate of main combustion period in O2 / CO2 environment increased by about 37.6%.