稀燃CNG发动机燃烧稳定性的数值模拟研究

利用三维燃烧模型对稀燃CNG发动机的燃烧过程进行数值模拟,研究在引入过量空气系数的循环变动情况下,发动机转速对稀燃CNG发动机燃烧循环变动程度的影响。通过对比计算和试验结果,验证了模型的可靠性,并且分析了燃烧过程中不同时刻下的缸内温度分布情况。根据多个循环的计算结果,定量分析了发动机转速对燃烧循环变动的影响,转速的提高将使燃烧循环变动减弱。计算还得出,转速的改变对燃烧循环变动的影响程度大于对燃烧峰值压力均值的影响。

Use of Three-dimension Models to Study the Cyclic Variations in a Lean Burn CNG Engine

In this paper,three-dimension models have been used to simulate the combustion process on a lean burn CNG engine.The effects of engine speed on combustion cyclic variations were analyzed when the cyclic equivalence ratio variations existed.The numerical models were validated by comparison of predicted and experimental in-cylinder mean pressure.Then the in-cylinder temperature distributions in combustion processes were analyzed.According to computed results of the large number of cycles,the effects of engine speed on combustion cyclic variations were discussed.Results showed that the less combustion cyclic variations,the higher engine speeds.Results also indicated that the engine speed had a larger influence on combustion cyclic variations than the peak pressure.