In the present work, the effects of two synthetic jet orientations on the Nusselt number during combined convection heat transfer are investigated. The experimental study was conducted using two synthetic jet orientations−horizontal and vertical, and eight different Reynolds numbers, ranging from 0 to 1440. The temperatures were measured by using five thermocouples positioned at different locations, including heat sink surfaces and a heater. A pneumatic cylinder was employed to supply a low-velocity synthetic jet to a heat sink surface. According to the results, the local heat transfer coefficient decreases with increasing heat transfer length. The heat sink in the horizontal arrangement has a higher average heat transfer coefficient, by up to 12.9%, than that in the vertical arrangement. At the Reynolds number of 1440, the synthetic jet in the horizontal orientation produces a Nusselt number 2.2 times higher than natural convection alone. According to the developed empirical correlation, the combined convection Nusselt number is proportional to the Reynolds number and to the Prandtl number. The forced convection performance during combined convection heat transfer depends on free convection and the average Grashof number. The gradient of the combined convection Nusselt number F is linearly proportional to the Grashof number.

中文翻译：

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对流传热综合射流性能的实验研究

在目前的工作中，研究了在对流传热过程中两个合成射流方向对努塞尔数的影响。实验研究使用水平和垂直两个合成射流方向以及从0到1440的八个不同的雷诺数进行。通过使用五个位于不同位置（包括散热片表面和加热器）的热电偶来测量温度。采用气压缸向散热器表面供应低速合成射流。根据结果​​，局部传热系数随着传热长度的增加而减小。水平布置的散热器比垂直布置的散热器具有更高的平均传热系数，最高可达12.9％。雷诺数为1440时，水平方向的合成射流产生的努塞尔数比仅自然对流高2.2倍。根据发达的经验相关性，对流努塞尔特数与雷诺数和普朗特数成正比。组合对流传热过程中的强制对流性能取决于自由对流和平均Grashof数。对流努塞尔特数F的梯度与Grashof数成线性比例关系。组合对流传热过程中的强制对流性能取决于自由对流和平均Grashof数。对流努塞尔特数F的梯度与Grashof数成线性比例关系。组合对流传热过程中的强制对流性能取决于自由对流和平均Grashof数。对流努塞尔特数F的梯度与Grashof数成线性比例关系。