Abstract Experiments were conducted in a wind tunnel to investigate the effect of periodic forcing on the wake of a circular cylinder specially designed for independent control of the phase of forcing from slits located on opposite sides. Tests were conducted at Reynolds number (Re) of 12,000, based on diameter (D). Wake was forced at subharmonic and harmonic frequencies at constant blowing coefficient. Measurements consisted of wake pitot surveys, hotwire anemometry, and Particle Image Velocimetry. A 20% reduction in drag was achieved when the two slits operated in-phase at third harmonic. The drag reduction, however, was 18% when the two slits operated in an out-of-phase mode for the same frequency. Wake lock-in was observed for the out-of-phase forcing case. Wake power spectrum indicated the effectiveness of both types of forcing in suppressing the primary instability. This was also evident from the results of the Proper Orthogonal Decomposition of the PIV data and turbulence statistics.

中文翻译：

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受同相和异相周期性强迫的汽缸尾流

摘要 在风洞中进行了实验，以研究周期性强迫对圆柱体尾流的影响，该圆柱体专为独立控制位于相对两侧的狭缝的强迫相位而设计。基于直径 (D)，以 12,000 的雷诺数 (Re) 进行测试。以恒定吹动系数在次谐波和谐波频率下强制唤醒。测量包括尾流皮托管测量、热线风速测量和粒子图像测速。当两个狭缝以三次谐波同相运行时，阻力减少了 20%。然而，当两个狭缝以异相模式在相同频率下运行时，阻力减少了 18%。在异相强迫情况下观察到唤醒锁定。尾流功率谱表明两种类型的强迫在抑制初级不稳定性方面的有效性。从 PIV 数据和湍流统计的适当正交分解的结果中也可以看出这一点。