论文标题
电击管的特性在非常高的冲击马赫数下产生的可压缩涡流环
Characteristics of shock tube generated compressible vortex rings at very high shock Mach numbers
论文作者
论文摘要
通常在冲击管的开口端形成的可压量涡旋环在其形成，演变和传播过程中通常会根据冲击马赫数（MS）和出口流条件显示出有趣的现象。到目前为止，文献中研究的可压缩涡流环（MV）的马赫数是亚音速的，因为所考虑的冲击管压力比（PR）相对较低。在这项数值研究中，我们着重于低到高涡流环数（0.31 <mV <1.08）病例，特别关注实验中未报告的非常高的MV病例，因此在实验室中很难获得。首次将氢作为冲击管内的驱动器部分气体，首次获得超音速压缩涡流环（MV> 1）。已经确定，基于SST K-ω的DES湍流模型比在涡环开发的不同阶段的先前发表的结果更好地复制了实验观察。 DES是LES和RANS方法的内置混合物，可以自动切换到LES区域中的子网格尺度（SGS）模型（即具有不同尺度的涡流结构），并在该区域的其余部分（即，在网格间距大于湍流的长度尺度上）。 DES模型可以预测剪切层涡旋的特征以及实验测量中报告的反向旋转环（CRVR）。除了通常的CRVR之外，在不同径向位置的主涡流环后面的多个三重点和相应的滑行剪切层以及相应的滑移剪切层以及相应的剪切层的形成似乎是高马赫数涡流环的独特特征。对于高PR，H2，在编队阶段的情况，形成了反向循环的涡流层（主要涡旋环）（contd ...）
Compressible vortex rings, usually formed at the open end of a shock tube, often show interesting phenomena during their formation, evolution, and propagation depending on the shock Mach number (Ms) and exit flow conditions. The Mach number of the translating compressible vortex rings (Mv) investigated so far in the literature is subsonic as, the shock tube pressure ratio (PR) considered is relatively low. In this numerical study we focus on low to high vortex ring Mach numbers (0.31 < Mv < 1.08) cases with a particular focus on very high Mv cases that are not been reported in experiments as, it is difficult to obtain in laboratory. Using hydrogen as a driver section gas inside the shock tube, a supersonic compressible vortex ring (Mv > 1) is obtained for first time. It is established that the SST k-ω based DES turbulent model replicates the experimental observation better than the previously published results at different stages of development of the vortex ring. DES, which is an inbuilt hybrid of LES and RANS approaches is evoked that can automatically switch to the sub-grid scale (SGS) model in the LES regions (i.e. with different scale vortical structures) and to a RANS model in the rest of the region (i.e. where the grid spacing is greater than the turbulent length scale). The DES model can predict characteristics of the shear layer vortices as well as counter-rotating vortex rings (CRVRs) as reported in the experimental measurements. Formation of multiple triple points and the corresponding slip-stream shear layers and thus multiple CRVRs behind the primary vortex ring at different radial locations, in addition to the usual CRVRs, appears to be a unique characteristic for high Mach number vortex rings. For high PR, H2, case during formation stage, a vortex layer of reverse circulation (that of primary vortex ring) is formed (contd...)
