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首页> 外文期刊>Journal of Thermophysics and Heat Transfer >Enhancement of Heat Transfer over a Cylinder by Acoustic Excitation
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Enhancement of Heat Transfer over a Cylinder by Acoustic Excitation

机译：通过声激发增强圆柱上的传热

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Experiments were performed to demonstrate enhancement of heat transfer around a horizontal cylinder by the presence of acoustic excitation. The horizontal cylinder was heated uniformly and placed inside a wind tunnel. The wall temperatures around the cylinder were measured and are used to determine the local heat transfer in the circumferential direction. To avoid interference with the flow, the acoustic generator, which was a loud speaker, was placed downstream of the cylinder. The frequency of the sound F_e, was set equal to the natural frequency, F_n, of the shedding vortex in the wake or a multiple of F_n. Therefore, synchronization of vortex shedding with acoustic wave can be expected. The excitation frequencies selected were F_e/F_n = 1, 2, 3, up to 8. Other frequencies at F_e/F_n = 1.5, 2.5, 3.5, up to 7.5 were also selected for comparison. During the experiments, the sound pressure varied from 0 to 100 dB and the Reynolds number varied from 2938 to 8814. The heat transfer around the cylinder was found to be significantly enhanced by the acoustic waves. More detailed measurements for the energy spectrum of the acoustic waves generated by the current speaker were made. This provides a better understanding of the physical process. Flow visualization is also performed to demonstrate synchronization of vortex shedding with acoustic excitation. The effect of sound pressure levels and Reynolds numbers on the wall heat transfer are presented and discussed.
机译：进行实验以证明在存在声激发的情况下围绕水平圆柱体的传热增强。将水平圆筒均匀地加热并放置在风洞内。测量圆柱体周围的壁温，并将其用于确定沿圆周方向的局部传热。为了避免干扰气流，将声音发生器（该扬声器为扬声器）放置在圆柱体的下游。声音的频率F_e设置为等于尾流中脱落涡的固有频率F_n或F_n的倍数。因此，可以预期涡旋脱落与声波的同步。所选的激励频率为F_e / F_n = 1、2、3，最高为8。还选择了F_e / F_n = 1.5、2.5、3.5，最高7.5的其他频率进行比较。在实验过程中，声压从0到100 dB变化，雷诺数从2938到8814变化。发现圆柱周围的传热被声波显着增强。对当前扬声器产生的声波的能量谱进行了更详细的测量。这样可以更好地了解物理过程。还进行流动可视化以证明涡旋脱落与声激发的同步。提出并讨论了声压级和雷诺数对壁传热的影响。

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