高度欠膨胀射流的瞬态近场结构
发布时间：2019-06-13 18:19
【摘要】：为增加对高度欠膨胀射流物理流动规律,特别是对其近场瞬态结构特征的认识,利用基于Open FOAM函数库开发的可压缩流动求解器astro Foam,对喷压比(NPR)分别为5.60,7.47,9.34,11.21,雷诺数Re约105的高度欠膨胀射流进行了三维大涡模拟。首先讨论了射流近场的时均流动特征,发现大涡模拟计算成功捕捉到了高度欠膨胀射流近场的典型结构,并与实验测量和文献结果吻合较好。重点研究了高度欠膨胀射流近场的瞬态非定常特征,给出了实验难以测量的射流近场波系结构的建立过程,发现其主要受初始条件的主导,喷压比的影响较为有限。揭示了马赫桶内精细的小尺度胞格结构,并通过高速脉冲纹影图片予以初步证实。定量地研究了射流马赫盘的振荡特征,发现其具有强瞬态和高非线性的特点,不同喷压比下马赫盘的振荡周期相同,主要受f=5.298k Hz的轴对称模态的主导。
[Abstract]:In order to increase the understanding of the physical flow law of highly underexpanded jet, especially the characteristics of its near-field transient structure, the three-dimensional large vortex simulation of the highly underexpanded jet with injection pressure ratio (NPR) of 5.60, 7.47, 9.34, 11.21 and Reynolds number Re about 105 is carried out by using the compressible flow solver astro Foam, developed based on Open FOAM function library. Firstly, the time-averaged flow characteristics of the jet near the field are discussed, and it is found that the typical structure of the near field of the highly underexpanded jet is successfully captured by the large vortex simulation calculation, and the results are in good agreement with the experimental results and the literature results. The transient unsteady characteristics of the near field of the highly underexpanded jet are studied, and the establishment process of the near field wave system structure of the jet, which is difficult to be measured by experiments, is given. It is found that the structure of the jet near field is mainly dominated by the initial conditions, and the influence of the jet pressure ratio is limited. The fine small scale cell structure in the Mach bucket is revealed and preliminarily confirmed by the high speed pulse schlieren picture. The oscillation characteristics of jet Mach disk are studied quantitatively. It is found that it has the characteristics of strong transient and high nonlinear. The oscillation period of Mach disk is the same under different injection pressure ratios, which is mainly dominated by the axisymmetric mode of f 鈮，
本文编号：2498716
[Abstract]:In order to increase the understanding of the physical flow law of highly underexpanded jet, especially the characteristics of its near-field transient structure, the three-dimensional large vortex simulation of the highly underexpanded jet with injection pressure ratio (NPR) of 5.60, 7.47, 9.34, 11.21 and Reynolds number Re about 105 is carried out by using the compressible flow solver astro Foam, developed based on Open FOAM function library. Firstly, the time-averaged flow characteristics of the jet near the field are discussed, and it is found that the typical structure of the near field of the highly underexpanded jet is successfully captured by the large vortex simulation calculation, and the results are in good agreement with the experimental results and the literature results. The transient unsteady characteristics of the near field of the highly underexpanded jet are studied, and the establishment process of the near field wave system structure of the jet, which is difficult to be measured by experiments, is given. It is found that the structure of the jet near field is mainly dominated by the initial conditions, and the influence of the jet pressure ratio is limited. The fine small scale cell structure in the Mach bucket is revealed and preliminarily confirmed by the high speed pulse schlieren picture. The oscillation characteristics of jet Mach disk are studied quantitatively. It is found that it has the characteristics of strong transient and high nonlinear. The oscillation period of Mach disk is the same under different injection pressure ratios, which is mainly dominated by the axisymmetric mode of f 鈮，
本文编号：2498716
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