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Flow control of wingtip vortices through synthetic jets
Experimental Thermal and Fluid Science ( IF 2.8 ) Pub Date : 2021-07-22 , DOI: 10.1016/j.expthermflusci.2021.110489
Mirko Zaccara 1 , Gerardo Paolillo 1 , Carlo Salvatore Greco 1 , Tommaso Astarita 1 , Gennaro Cardone 1
Affiliation  

The effectiveness of synthetic jet actuation on the wingtip vortices produced by an unswept, low aspect ratio, rectangular wing at a chord Reynolds number of 8.16×104 is experimentally investigated. The synthetic jet is operated at different actuation frequencies and amplitudes in order to investigate five different control cases characterized by different momentum coefficients and dimensionless frequencies, for a comprehensive parametric study. In particular, the instability frequencies (known as Crow and Widnall) characterizing the wingtip vortex dissipation, are chosen among the tested synthetic jet actuation frequencies. A phase-locked stereoscopic particle image velocimetry is employed to analyze the development of the wingtip vortices in the near wake at a distance from the wing trailing edge of 3 chord lengths. The time-averaged results suggest that the synthetic jet actuation greatly affects the wingtip vorticity distribution causing an outward diffusion which increases with the actuation frequency, with a maximum reduction of 46% on the peak value. On the other hand, when the synthetic jet is operated at the Crow instability frequency, the wingtip induced velocity shows its maximum decrease equal to 29% with respect to the baseline case. The phase-averaged analysis reveals a clear relation between the synthetic jet blowing and suction phases and the periodic variation of the vortices features. In correspondence to the blowing phase, the wingtip vortices undergo a huge diffusion and they are characterized by a larger diameter, higher circulation, and lower induced velocity. These findings confirm that this synthetic jet control configuration can represent a useful device to promote the vortex dissipation and reduce the wake vortex hazard.



中文翻译:

通过合成射流控制翼尖涡流

合成射流驱动对由未后掠的低展弦比矩形机翼在弦雷诺数为 1 时产生的翼尖涡流的有效性 8.16×104进行了实验研究。合成射流以不同的驱动频率和振幅运行,以研究以不同动量系数和无量纲频率为特征的五种不同控制情况,以进行全面的参数研究。特别是,表征翼尖涡流耗散的不稳定性频率(称为 Crow 和 Widnall)是在经过测试的合成喷气驱动频率中选择的。采用锁相立体粒子图像测速技术分析了距翼后缘3弦长一段距离的近尾流中翼尖涡旋的发展。时间平均结果表明,合成喷气驱动极大地影响了翼尖涡度分布,导致向外扩散,随着驱动频率的增加而增加,峰值最大减少 46%。另一方面,当合成喷气机在 Crow 不稳定频率下运行时,翼尖诱导速度显示其最大下降等于 29% 相对于基线情况。相位平均分析揭示了合成射流吹气和吸入相位与涡流特征的周期性变化之间的明确关系。与吹气阶段相对应,翼尖涡流经历了巨大的扩散,它们的特点是直径更大,环流更大,诱导速度更低。这些发现证实,这种合成射流控制配置可以代表一种有用的装置,以促进涡流消散和减少尾涡危险。当合成喷气机在 Crow 不稳定性频率下运行时,翼尖诱导速度显示出其最大下降幅度,与基线情况相比下降了 29%。相位平均分析揭示了合成射流吹气和吸入相位与涡流特征的周期性变化之间的明确关系。与吹气阶段相对应,翼尖涡流经历了巨大的扩散,它们的特点是直径更大,环流更大,诱导速度更低。这些发现证实,这种合成射流控制配置可以代表一种有用的装置,以促进涡流消散和减少尾涡危险。当合成喷气机在 Crow 不稳定性频率下运行时,翼尖诱导速度显示出其最大下降幅度,与基线情况相比下降了 29%。相位平均分析揭示了合成射流吹气和吸入相位与涡流特征的周期性变化之间的明确关系。与吹气阶段相对应,翼尖涡流经历了巨大的扩散,它们的特点是直径更大,环流更大,诱导速度更低。这些发现证实,这种合成射流控制配置可以代表一种有用的装置,以促进涡流消散和减少尾涡危险。相位平均分析揭示了合成射流吹气和吸入相位与涡流特征的周期性变化之间的明确关系。与吹气阶段相对应,翼尖涡流经历了巨大的扩散,它们的特点是直径更大,环流更大,诱导速度更低。这些发现证实,这种合成射流控制配置可以代表一种有用的装置,以促进涡流消散和减少尾涡危险。相位平均分析揭示了合成射流吹气和吸入相位与涡流特征的周期性变化之间的明确关系。与吹气阶段相对应,翼尖涡流经历了巨大的扩散,它们的特点是直径更大、环流更大、诱导速度更低。这些发现证实,这种合成射流控制配置可以代表一种有用的装置,以促进涡流消散和减少尾涡危险。

更新日期:2021-08-10
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