Abstract An experimental study on the flow characteristics of an array of finite-span Synthetic Jets (SJs) issuing at different conditions in a quiescent ambient was carried out by means of hot-wire and phase-locked planar Particle Image Velocimetry measurements. The actuator comprises twelve slots with aspect ratio 15 fed by a common resonant cavity and off-centered from the axis of the cavity. The frequency response indicates that the SJs are formed in the range of Stokes numbers between 4 and 12.5, in which two operating conditions were inspected yielding the SJs issuing either at Reynolds ( Re ) and Strouhal ( St ) numbers of Re = 40 and St = 0.84 or Re = 213 and St = 0.50. It is found that, for the case at Re = 40 and St = 0.84, the flow field undergoes the asymmetries of the actuator. The axis switching persists in the very-near field of the SJ array, while further downstream the spreading of each SJ becomes more pronounced promoting the jet interaction. For the case at Re = 213 and St = 0.50, the main flow direction along the cross-sectional plane tilts of 14.8° towards the side where the cavity extends. The formation of a recirculation region promotes the enhancement of turbulent dissipation mechanisms. The phase-average flow fields reveal that, similarly for both cases, the imprint of the vortical structures exhibits symmetric organization during the ejection phase.

中文翻译：

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静止环境中有限跨距合成射流阵列的流动表征

摘要 通过热线和锁相平面粒子图像测速测量，对在静止环境中不同条件下喷射的有限跨距合成射流（SJ）阵列的流动特性进行了实验研究。致动器包括十二个槽，其纵横比为15，由公共谐振腔馈送并且偏离腔的轴线。频率响应表明 SJ 是在 4 到 12.5 之间的斯托克斯数范围内形成的，其中检查了两种操作条件，产生了在雷诺 ( Re ) 和 Strouhal ( St ) 数 Re = 40 和 St = 0.84 或 Re = 213 且 St = 0.50。发现，对于 Re = 40 和 St = 0.84 的情况，流场经历了执行器的不对称性。轴切换在 SJ 阵列的非常近的场中持续存在，而在更远的下游，每个 SJ 的扩散变得更加明显，促进了射流相互作用。对于 Re = 213 和 St = 0.50 的情况，沿横截面的主要流动方向向空腔延伸的一侧倾斜 14.8°。再循环区域的形成促进了湍流耗散机制的增强。相均流场表明，对于这两种情况，类似地，涡流结构的印记在喷射阶段表现出对称组织。朝向空腔延伸的一侧 8°。再循环区域的形成促进了湍流耗散机制的增强。相均流场表明，对于这两种情况，类似地，涡流结构的印记在喷射阶段表现出对称组织。朝向空腔延伸的一侧 8°。再循环区域的形成促进了湍流耗散机制的增强。相均流场表明，对于这两种情况，类似地，涡流结构的印记在喷射阶段表现出对称组织。