An experimental investigation of the flow-field and thermal characteristics of synthetic jet impingement with different waveforms
An experimental investigation of the flow-field and thermal characteristics of synthetic jet impingement with different waveforms
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DOI：
10.1016/j.ijheatmasstransfer.2022.122534
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发表时间：
2022-05
影响因子：
5.2
通讯作者：
Pushpanjay K. Singh;M. Renganathan;H. Yadav;S. Sahu;P. K. Upadhyay;A. Agrawal
中科院分区：
文献类型：
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作者：
Pushpanjay K. Singh;M. Renganathan;H. Yadav;S. Sahu;P. K. Upadhyay;A. Agrawal
本文报道了正弦和方波电磁驱动圆孔合成射流的流动和热行为。研究了雷诺数(1656-2218)、无量纲轴向距离(1-25)和激励频率(100-175赫兹)对热工性能的影响。采用热线风速仪和粒子图像测速技术，将热行为与流体力学相耦合，对流场进行了研究。表面温度是用红外热像仪测量的。与方波合成射流相比，正弦波形合成射流的平均努塞尔数提高了20.86%。然而，在停滞区，方形波形的换热比正弦波形高18.94%。流动动力学揭示了换热速率变化的底线流动物理。速度等值线呈光滑宽大的正弦波形。然而，在方形波形的情况下，速度分布较窄，这导致环境中的新鲜流体进入射流的卷吸减少。与方波相比，正弦波在其膜片谐振频率(150 GHz)下的质量流量高73.68%。分析了热线测速得到的速度信号的功率谱密度，以了解涡环的形成和传播。建立了正弦波和方波的平均Nusselt数的统一关联式。本实验研究结果对空间受限电子冷却合成射流的有效设计具有重要的指导意义。
Present experimental investigation reports the flow and thermal behavior of electromagnetically actuated circular orifice synthetic jet involving sinusoidal and square waveforms. The effect of Reynolds number (1656–2218), dimensionless axial distance (1–25), and the excitation frequency (100–175 Hz) on the thermal performance is studied here. The flow field is investigated using the hot wire anemometry and particle image velocimetry technique to couple the thermal behavior with fluid dynamics. The surface temperature is measured using an infrared thermal imaging camera. The average Nusselt number for synthetic jet with sinusoidal waveform is found to be 20.86% higher compared to the synthetic jet with square waveform. However, in the stagnation region, the square waveform exhibits 18.94% higher heat transfer compared to the sinusoidal waveform. The flow dynamics reveal the underline flow physics for the variation in the heat transfer rate. The velocity contours show a smooth and wide top hat with the sinusoidal waveform. However, in the case of square waveform, the velocity profile is narrow, which results in a decrease in entrainment of fresh ambient fluid into the jet. The sine wave exhibits 73.68% higher mass flow rate compared to square wave pattern at its diaphragm resonance frequency (150 Hz). The power spectral density of the velocity signal, obtained from the hot wire anemometry, is analyzed to understand the formation and propagation of vortex rings. A unified correlation for average Nusselt number is developed for both sinusoidal and square waveforms. The results obtained from the present experimental investigation provide significant guidance for the efficient design of synthetic jets for space-constrained electronics cooling.