Stereoscopic Micro-PIV measurement of the flow dynamics in a spherical dimple

IF 2.3 3区 工程技术 Q2 ENGINEERING, MECHANICAL Experiments in Fluids Pub Date : 2024-08-06 DOI:10.1007/s00348-024-03858-1
Lukas Rohwer, Hannes Deponte, Wolfgang Augustin, Stephan Scholl
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Abstract

One way to increase the thermal efficiency of heat exchangers is to structure the heat transfer surfaces with dimples, resulting in an enlarged surface area and intensified turbulence in the fluid flow. The increased turbulence also causes higher wall shear stress, which potentially suppresses the deposition of particles and supports a self-cleaning of the surface. For a deeper understanding of these phenomena, the flow dynamics inside the dimple were observed experimentally with Stereoscopic Micro-Particle Image Velocimetry (Stereo µPIV). The formation of an unsteady oscillating vortex, which leads to an asymmetric trail downstream of the dimple, is visualized. The significant influence of the dimple geometry on heat transfer enhancement is shown, and the most beneficial geometric ratio of the spherical dimple regarding its ability to increase turbulence is identified. A comparison of the local flow velocities with the results of the numerically and experimentally observed patterns of the deposited particles caused by the dimple’s self-cleaning effect shows a good match.

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对球形凹陷中的流动动力学进行立体微观 PIV 测量
提高热交换器热效率的一种方法是在传热表面设计凹槽,从而扩大表面积,加强流体流动中的湍流。增加的湍流还能提高壁面剪应力,从而抑制颗粒沉积并支持表面自清洁。为了更深入地了解这些现象,我们使用立体微观粒子图像测速仪(Stereo µPIV)对凹陷内部的流动动力学进行了实验观察。结果表明,不稳定振荡漩涡的形成导致了酒窝下游的不对称尾迹。图中显示了凹痕几何形状对热传递增强的重要影响,并确定了球形凹痕在增加湍流能力方面最有利的几何比率。将局部流速与通过数值和实验观察到的由酒窝自清洁效应引起的沉积颗粒形态结果进行比较,结果显示两者非常吻合。
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来源期刊
Experiments in Fluids
Experiments in Fluids 工程技术-工程:机械
CiteScore
5.10
自引率
12.50%
发文量
157
审稿时长
3.8 months
期刊介绍: Experiments in Fluids examines the advancement, extension, and improvement of new techniques of flow measurement. The journal also publishes contributions that employ existing experimental techniques to gain an understanding of the underlying flow physics in the areas of turbulence, aerodynamics, hydrodynamics, convective heat transfer, combustion, turbomachinery, multi-phase flows, and chemical, biological and geological flows. In addition, readers will find papers that report on investigations combining experimental and analytical/numerical approaches.
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