切向进气道发动机缸内流场三维瞬态数值模拟

以动态网格技术为基础,采用三维、可压、黏性、湍流模型,应用控制容积法,对切向进气道发动机进气系统三维流场特性进行了瞬态数值研究。研究发现,在进气过程的初始阶段,缸内始终存在一对旋涡,并且沿气缸轴线向下缸内流体出现逐步融合的趋势;随着曲轴转角进一步增大,约在100°CA时缸内靠近活塞的横截面上出现单旋涡;在140°CA时,缸内横截面上大部分都只有单旋涡存在,只在靠近缸盖的横截面上有一个面积较大的主旋涡和一个面积很小的旋涡;当曲轴转角进一步增大,缸内仅存在一个单旋涡,流场压力趋于均匀。采用三维瞬态数值计算可获得稳态计算和试验难以得到的进气系统三维流场流动规律,为进气系统的优化设计提供可靠依据。

3D Transient Numerical Simulation of Flow Field in Cylinder of the Engine with Tangent Intake Duct

Based on the dynamic mesh technique and applying the control volume method,the 3D transient flow field has been investigated at the tangent intake system of engine by using the 3D compressible viscous turbulent flow model.The results show that there are a couple of vortexes trending blend along the axes in the cylinder at the initial phase of intake process.While the crank angle increasing about 100°,there only exists single vortex at the cross section near the piston.When the crank angle reaches 140°,single vortex is dominant at most of cross sections,and both a huge and a tiny vortex exist near the cylinder cover.With increasing crank angle,and moth than 140°,single vortex and uniform pressure field in the cylinder is taken place. Hence,it is clear that the 3D transient simulation can get the law of flow field that is hard to get with the experiment or steady simulation.It is also rather valuable for optimal designing the intake system.