An Experimental Investigation on the Mechanism of Tollmien-Schlichting Waves for a NACA 0012 Aerofoil
An Experimental Investigation on the Mechanism of Tollmien-Schlichting Waves for a NACA 0012 Aerofoil
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NACA 0012 机翼 Tollmien-Schlichting 波机理的实验研究
DOI：
10.2514/6.2019-2609
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
M. Azarpeyvand
中科院分区：
文献类型：
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作者：
B. Zang;Y. Mayer;M. Azarpeyvand
本研究采用高度仪表化的NACA 0012翼型，在中等雷诺数（基于弦长，雷诺数从1.8 × 105到4.6 × 105）下，对Tollmiem-Schlicting（T-S）不稳定性及其相关的翼型噪声的发展进行了实验研究。测量的远场噪声谱清晰地捕获了以主峰为中心的宽带和多个离散音调噪声，与现有文献一致。对近场压力和尾流速度谱的检查表明，主音及其谐波在整个尾流场传播，既向上游延伸到前缘，又向下游延伸到近尾流区域之外，这与Paterson等人提出的涡流噪声特性一致。另一方面，当f = 9时，主音的比例非常好。4 n U 0 . 8在整个范围内的低攻角的低流速，证实了与Tam的反馈回路机制。2来自近场和远场噪声测量的证据促使进一步研究近场压力脉动和尾流速度之间的相关性。结果表明，在翼型后缘附近的近尾迹区，不仅存在与流体动力不稳定性特征相一致的周期性大尺度结构，而且还存在相反转现象。结果表明，由T-S不稳定性引起的翼型噪声是涡扰动和近尾流反馈回路及其动态复杂相互作用的综合结果。
The present study investigates experimentally on the development of Tollmiem-Schlicting (T-S) instabilities and its associated aerofoil noise using a highly instrumented NACA 0012 profile with four angles of attack ( α = 0 ◦ , 2 ◦ , 4 ◦ and 6 ◦ ) at moderate Reynolds numbers, ranging from 1.8 × 10 5 to 4.6 × 10 5 based on the chord length. The measured far-field noise spectra captured clearly both the broadband and multiple discrete tonal noises centred around a dominant peak, consistent with the existing literatures. Examinations on the near-field pressure and wake velocity spectra suggests that the dominant tones and its harmonics propagate over the entire flow field, extending both upstream to the leading-edge as well as downstream beyond the near-wake region, which agrees with the characteristics of vortex noise as proposed by Paterson et al. 1 On the other hand, the dominant tones scale very well with f = 9 . 4 n U 0 . 8 across the entire range of flow velocities at lower angles of attack, corroborating with the feedback loop mechanisms derived by Tam. 2 Evidences from the near-and far-field noise measurements prompt further investigations into the correlations between near-field pressure fluctuations and wake velocity. The results suggest not only the existence of periodic large-scale structures, consistent with the characteristics of hydrodynamic instability, but also a phase reversal in the near-wake region close to the aerofoil trailing-edge. The present results demonstrate that the aerofoil noise stemming from T-S instabilities could be attributed to a combination of the vortex disturbances and near-wake feedback loop and their dynamic and complex interactions.