Abstract How forcing frequency of synthetic jet would affect heat transfer attracts wide attention, however, studies conducted by different authors or the same study but with slightly distinct conditions often led to disparate results. In regard to the forcing frequency-induced intricate phenomena in heat transfer process of synthetic jet, a mechanism analysis focusing on the effect of St is proposed in this work. In the present study, the emphases are to explore the effects of frequency (f = 10–75 Hz) and dimensionless parameters, i.e. Reynolds number (Re = 10,000–20,000) as well as Strouhal number (St = 0.1285–0.4498), on these physical processes of synthetic jet. The results demonstrate that there is an interval of St from 0.24 to 0.48 that corresponds to the highest range of time-area averaged Nusselt number under each Re. Moreover, Re or frequency would largely influence amplitude and variation trend of area averaged Nusselt number with normalized time respectively. However, interestingly, the variation trend of area averaged Nusselt number with respect to normalized time exhibits high similarity under the conditions of the same St even with different Re and frequency. Furthermore, the evolutions of flow field with normalized time are also analogous at the same St, which can lead to the similarity in the variation of heat transfer rate.

中文翻译：

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合成冲击射流传热过程中主要参数的数值分析

摘要 合成射流的强迫频率如何影响传热引起广泛关注，但不同作者或同一研究但条件略有不同的研究往往会导致不同的结果。针对合成射流传热过程中强迫频率引起的复杂现象，本文提出了一种关注St效应的机理分析。在本研究中，重点是探索频率 (f = 10–75 Hz) 和无量纲参数，即雷诺数 (Re = 10,000–20,000) 以及 Strouhal 数 (St = 0.1285–0.4498) 对这些合成射流的物理过程。结果表明，在每个 Re 下，St 的区间为 0.24 到 0.48，对应于时区平均努塞尔数的最高范围。而且，Re或频率分别对归一化时间的面积平均努塞尔数的幅度和变化趋势有很大影响。然而，有趣的是，即使在不同 Re 和频率的情况下，面积平均努塞尔数相对于归一化时间的变化趋势在相同的 St 条件下也表现出高度的相似性。此外，流场随归一化时间的演变也在同一 St 处类似，这可能导致传热速率变化的相似性。