Fluctuation Characteristics of Wavy Vortex Field Within Annular Gap in Taylor-Couette
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摘要:
为研究Taylor-Couette环隙流场波状涡涡间的波动变化情况，采用大涡模拟（LES）方法对Taylor-Couette波状涡流场进行瞬态数值模拟，并从二维和三维的角度对环隙间波状涡流场进行分析. 结果表明：波状涡流场中二维环隙子午面速度矢量场存在周期性波动变化特征，在周期始末时刻速度矢量场基本保持一致；涡交界位置处的轴向速度方向在不断发生周期性变化，径向和切向速度方向保持不变；涡对间各向速度值均大于涡对内的涡间，主流液体传递主要发生在外向流的涡对间；另一方面，三维波状涡流场涡旋周期波动现象明显，也具有周期特征，各工况（10、20、30、40 r/min）的周期分别为12.94、6.80、1.93、1.49 s；随着旋转雷诺数增大，涡旋波动幅度大幅减小，波动周期也缩短；环隙间主流液体在涡间的周期性流动带动流体微团在环隙间绕内筒做螺旋偶合涡旋转运动.
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关键词:
- Taylor-Couette /
- 波状涡 /
- 速度矢量场 /
- 环隙 /
- 波动特征
Abstract:The large eddy simulation (LES) method was applied to transiently simulate the wavy vortex field within the annular gap in Taylor-Couette and investigate the variation of fluctuations between wavy vortices. The wavy vortex field within the annulus gap was investigated from both two-dimensional and three-dimensional perspectives. The results indicate that the velocity vector field on the meridian plane of the two-dimensional wavy vortex field within the annular gap exhibits periodic fluctuation characteristics. The velocity vector field remains essentially the same at the beginning and end moments of the cycle. The axial velocity direction at the vortex junction changes constantly and periodically, while the radial and tangential velocity directions remain constant. The velocity values of the vortex pairs are greater than those of the vortex pairs inside the vortex, and the mainstream liquid transfer mainly occurs between the vortex pairs in the outward flow. Additionally, the fluctuation phenomenon of the three-dimensional wavy vortex field is clearly evident and exhibits periodic characteristics. The cycles for each working condition (10, 20, 30, and 40 r/min) are 12.94 seconds, 6.80 seconds, 1.93 seconds, and 1.49 seconds, respectively. With the increase in rotational Reynolds number, there is a significant decrease in vortex fluctuation amplitude and a reduction in the duration of fluctuations. The periodic flow transport of the mainstream liquid between vortices within the annulus gap propels fluid microclusters to perform a spiral-coupled vortex rotation around the inner cylinder within the annulus gap.
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Key words:
- Taylor-Couette /
- wavy vortex /
- velocity vector field /
- annular gap /
- fluctuation characteristic
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图 1 Taylor-Couette反应器几何模型及网格划分示意
Figure 1. Geometry model and meshing for Taylor-Couette reactor
图 2 大涡模拟与PIV测量环隙子午面速度矢量图对比
Figure 2. Comparison between LES and PIV measurement of velocity vector on meridian plane
图 4 各转速工况下速度矢量图周期变化过程
Figure 4. Periodic variations in velocity vector diagram at different rotational velocities
图 5 各转速工况特征线上一个周期内轴向速度随时间的变化
Figure 5. Variation of axial velocity with time along characteristic line at different rotational velocities within a cycle
图 6 各转速工况特征线上一个周期内径向速度随时间的变化
Figure 6. Variation of radial velocity with time along characteristic line at different rotational velocities within a cycle
图 7 各转速工况特征线上一个周期内切向速度随时间的变化
Figure 7. Variation of tangential velocity with time along characteristic line at different rotational velocities within a cycle
图 8 各工况特征线上各向最大速度对比
Figure 8. Comparison of maximum velocities along characteristic line under various working conditions
图 9 各工况三维涡旋等值面周期内变化
Figure 9. Variation of three-dimensional vortex isosurface within a cycle under various working conditions
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