柴油超临界喷雾大涡数值模拟研究

随着现代内燃机燃烧室内温度和压力的不断提升,液体燃料往往处于超临界状态,与亚临界状态相比,其喷雾射流行为特征发生了很大的变化。本研究采用大涡数值模拟方法对超临界环境下的单组分和多组分柴油表征燃料喷雾射流进行数值计算,对比了不同气体状态方程预测柴油表征燃料超临界射流行为的差异性,发现PR气体状态方程对正庚烷质量分数分布的模拟结果与实验值更接近,相较于其他状态方程表现更好;另外还发现本研究采用的多组分柴油表征燃料(正庚烷质量分数80%、甲苯质量分数10%、环己烷质量分数10%)可较好地反映超临界环境下真实柴油喷雾射流特征。

Study on Large Eddy Simulation of Diesel Supercritical Spray

With the constant increase of temperature and pressure in the combustion chamber of modern internal combustion engines,liquid fuel is often in the supercritical state,and compared with the subcritical state,its spray jet behavior characteristics have undergone great changes.In this study,the large eddy simulation method is used to numerically calculate the single-component and multi-component diesel surrogate fuel spray jets in supercritical environment,and the difference between different gas state equations in predicting the behavior of supercritical fuel injection of diesel fuel is compared.It is found that the simulation results of PR gas state equation on n-heptane mass fraction distribution are closer to the experimental values,with better results than other state equations.It is also found that the multi-component diesel characterized fuel(n-heptane mass fraction 80%,toluene mass fraction 10%,cyclohexane mass fraction 10%)used in this study can better reflect the characteristics of real diesel spray jet in supercritical environment.