亚网格湍动能及湍流弥散效应对燃油喷雾特性的影响

Influences of Subgrid Turbulent Kinetic Energy and Turbulent Dispersion on the Characteristics of Fuel Spray

采用大涡模拟方法和不同的雾化模型对定容弹中燃油喷射和雾化过程进行数值分析.着重探讨亚网格尺度湍动能,特别是燃油喷雾所诱导的亚网格湍能源项对液滴运动和喷雾特性的影响,并进一步探讨了亚网格气相湍动能对液滴弥散速度乃至喷雾场的影响.通过对不同的工况条件的模拟计算对喷雾的影响因素进行了讨论并与相关的实验进行了比较.计算结果表明,KH-RT破碎模型要优于MTAB模型,湍流弥散效应和亚网格湍动能喷雾源项对燃油喷雾有着重要的影响,其作用均是减少喷雾贯穿距,使模拟结果更接近于实验.其中,湍流弥散效应的影响更为显著.

The large eddy simulation approach and different breakup models are used to analyze fuel injection and atomization process in a constant volume combustion bomb. The study is focused on the influences of subgrid turbulent kinetic energy, especially the source term induced by fuel spray, on droplet movement and spray characteristics. The further study is made on the effects of subgrid kinetic energy on turbulent dispersion of droplets and fuel spray. Factors affecting fuel spray are discussed based on numerical computations under various operating conditions and then compared with experimental data. Computational results show that the KH-RT breakup model is superior to the MTAB model, and that both subgrid turbulent energy source/term induced by spray and turbulent dispersion of droplets have great effects on fuel spray, resulting in decreased spray penetration. The effect of turbulent dispersion is more prominent.