不同亚网格尺度应力模型在燃油喷雾大涡模拟中的应用

Application of Different Sub-Grid Models in the Large Eddy Simulation of Diesel Sprays

亚网格尺度应力模型是影响大涡模拟结果的一个关键因素.在K-方程亚网格湍动能模型的基础上,对其它比较常用的3种代数模型(Smagoringsky模型、动态Smagoringsky模型和WALE模型)在燃油喷雾中的适用性作了探讨.在定容弹中采用3个不同的燃油喷雾试验作为数值模拟的验证对象,分析了喷雾的演变过程.并将其应用于柴油发动机喷雾冷态研究中.结果可知,3个代数亚网格模型在蒸发和非蒸发过程中喷雾的演变过程基本与试验相符,液相贯穿距也与试验接近.K-方程模型较为准确,WALE模型在几种算例中也得到了较好的结果,Smagorinsky模型得到的液相贯穿距要稍长于其它几种模型.

Sub-grid turbulence model is a key factor affecting LES computation results.Besides the one equation sub-grid model（K-equation model）,the applicability of three common algebraic sub-grid mod-els（Smagorinsky model,dynamic Smagorinsky model and WALE model）on fuel spray in IC engines were analyzed.Three different experiments on the evolution process of fuel sprays in constant volume ves-sels were used to validate the numerical simulations.On the basis of this,the four sub-grid turbulent mod-els were applied on fuel spray in a diesel engine without combustion.Results show that the evolution of the liquid and vapor phases in spray predicted by the three sub-grid models are generally in agreement with the experimental data,and the predicted droplet penetrations are close to the measurement.Among these models the K-equation model seems to have the best performance,and WALE model can also provide reasonable results,while the liquid spray penetration predicted by the Smagorinsky model is larger than those by other models.