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为了对超声速弱欠膨胀冲击射流的流场结构细节进行研究,使用大涡模拟方法对其进行了数值模拟。利用三阶迎风和四阶对称紧致格式对无量纲化轴对称可压缩滤波N-S方程进行空间离散,时间上推进采用的是三阶精度的TVD型Rugge-kutta法。亚格子尺度模型采用的是修正Sm agorinsky涡粘性模型。通过与经典的冲击射流实验比较,证明了程序的可靠性。数值模拟得到了剪切层以及壁面射流中的涡结构和主射流中的激波结构,并且在此基础上对涡合并和板前激波和涡干扰现象进行了深入研究。发现涡合并现象主要出现在流场的上游,越往下游出现的几率越小;涡和板前激波的相互作用会引起激波位置和强度以及冲击平板上冲击区的压强的显著变化,同时也会导致涡的变形。
In order to study the structural details of the supersonic jet flow with weak expansion and infiltration, a large eddy simulation method was used to simulate the flow field. Third-order upwind and fourth-order symmetric compact formats are used to disperse the non-dimensional axisymmetric and compressible N-S equations in space. The third-order TVD Rugge-kutta method is used in time. The subgrid scale model uses a modified Sm agorinsky eddy viscosity model. By comparing with the classic impact jet experiment, the reliability of the program is proved. The vortex structures in the shear layer and the wall jet and the shock structures in the main jet are obtained by numerical simulation. Based on the above, the phenomena of vortex merger and pre-plate shock and vortex interference are studied in detail. It is found that the vortex merger occurs mainly upstream of the flow field, and the less the downstream occurs, the interaction between the vortex and the pre-plate shock will cause a significant change in the shock position and intensity as well as the pressure in the impact zone on the impact plate, Will lead to the deformation of the vortex.