| 圆柱绕流尾迹中涡量与温度标量的相平均分析 |
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| 引用本文： | 曹华丽,陈建钢,周同明,周裕.圆柱绕流尾迹中涡量与温度标量的相平均分析[J].实验流体力学,2015,0(1):15-24. |
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| 作者姓名： | 曹华丽 陈建钢 周同明 周裕 |
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| 作者单位： | 哈尔滨工业大学深圳研究生院 先进制造技术重点实验室,广东 深圳,518055 |
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| 基金项目： | JCYJ20120613134811717 |
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| 摘 要： | 实验研究了圆柱绕流尾迹中的三维涡拓扑结构特性以及湍流动量、热量输运特性。利用8支热线和4支冷线相结合的三维涡量探针分别测量从x/d=10~40的速度和温度脉动,采用相平均方法将圆柱绕流尾迹中的大尺度相干结构提取出来,剩余部分包括中等尺度相干结构和随机结构。结果发现:在x/d=10处ωz 与ωx 的等值线具有很强的相似性;随着流向的发展,ωx 和ωy 两分量受到更多来自两涡之间的流向“肋”结构的影响而呈现相似特征,证明了涡结构的三维特性。由于受到来自展向涡和流向肋结构的共同作用,导致展向热输运w~*~θ*在不同位置表现不一样,正涡中的w~*~θ*受到流向肋的拉伸作用而沿着分形线朝着鞍点偏移;而负涡内的w~*~θ*由于受到展向涡的卷起使得w~*~θ*和~ω*z 形状相似。随着流向的发展,展向热输运移向涡边界处,对卡门涡内净热量传递到周围流体中有贡献。同时还发现相干结构对横向和展向热输运的影响很相似。
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| 关 键 词： | 圆柱绕流尾迹 相干结构 温度标量 相平均 |
Three-dimensional vorticity and heat transport in a circular cylinder wake using phase-averaging method |
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| Cao Huali,Chen Jiangang,Zhou Tongming,Zhou Yu.Three-dimensional vorticity and heat transport in a circular cylinder wake using phase-averaging method[J].Experiments and Measur in Fluid Mechanics,2015,0(1):15-24. |
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| Authors: | Cao Huali Chen Jiangang Zhou Tongming Zhou Yu |
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| Affiliation: | Cao Huali;Chen Jiangang;Zhou Tongming;Zhou Yu;Key Lab of Advanced Manufacturing Technology,Shenzhen Graduate School,Harbin Institute of Technology;School of Civil and Resource Engineering,University of Western Australia; |
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| Abstract: | This work aims to provide insight into the three-dimensional aspects of momentum and heat transport in a turbulent cylinder wake.All three components of the velocity and vorticity vectors, along with the fluctuating temperatures,were simultaneously measured with an 8 hot-wire vorticity probe and four cold-wire probes.Measurement was made at x/d= 10~40 at a Reynolds number of 2540.A phase-averaging technique has been developed to detect reliably the coherent events,thus allo-wing the coherent contributions from various quantities associated with the vectors as well as passive scalar fields to be quantified accurately.The results show that there is a close similarity between the con-tour of spanwise vorticity and that of the streamwise vorticity at x/d= 1 0 ,due to the strong rolling up effect of the spanwise vortex.As x/d increases,the similarity betweenωx andωy contours can still be observed,resulting from the contributions of the rib-like structures.It exhibits significant three-dimensional qualities of the vortex structure in the near wake.While the coherent heat flux is largely as-sociated with the spanwise vortex rolls,the incoherent (or ‘remainder’)heat flux occurs between two successive opposite-signed vortices,rather than in the saddle region.Due to the combined effect of the spanwise vortex and the rib-like structure,the spanwise heat flux behaves quite differently at different locations.The w~*~θ* contour inside the negatively signed vortex is close to the vortex center,while the w~*~θ* inside the positive one is stretched to the saddle point aligning with the diverging separatrix.As x/d increases,the negative w~*~θ* contour becomes dominant and moves towards the vortex border, which contributes to the net heat transport out of the spanwise vortex.In addition,coherent motion con-tributes similarly to the longitudinal and spanwise heat flux components. |
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| Keywords: | near wake of circular cylinder coherent structure passive scalar phase-averaging |
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