Study on the effect of the boundary layer on the generation of aerodynamic noise and its control method.

边界层对气动噪声产生的影响及其控制方法研究

• 批准号: 09450084
• 负责人: FUJITA Hajime
• 金额: $ 8.64万
• 依托单位: NIHON UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450084/
• 关键词: Aerodynamics Noise; Aeolian Tone; Flow around cylinders; pressure Fluctuation; Karman Vortex; 円柱回り流れ

Experimental investigations were conducted in order to understand the characteristics of the Aeolian tone generated from two-dimensional square and circular cylinders with pressure transducers embedded on the surface. The following conclusions were obtainec.1) Square CylinderThe peak level of the Aeolian tone is maximum when the angle of attack is 0°, or, a flat surface is placed normal to the mean flow. The separated flow from the leading edge corner of the square cylinder reattaches to the side surface for the angle of attack between 10°to 13°. The surface pressure fluctuation becomes minimum at this angle of attack and consequently the Aeolian tone becomes minimum.2) Circular CylinderThe characteristics of the Aeolian tone radiated from a circular cylinder can be divided into three categories in the Reynolds number, Re, I.e. sub-critical (Re<3x10ィイD15ィエD1), super critical (3x10ィイD15ィエD1<Re<10ィイD16ィエD1) and trans-critical (Re>10ィイD16ィエD1) regions. In the sub-critical region, the surf … More ace pressure fluctuation is uniform spanwise and the coherence between the Aeolian tone is high and the Strouhal number is 0.2. In the super-critical region, the Strouhal number jumps up to 0.45 and the peak level of the Aeolian tone decreases sharply. The surface pressure fluctuation shows strong three-dimensionality and only a fractional part in spanwise shows high coherence with the Aeolian ire. In the trans-critical region, the Strouhal number returns to 0.2 and the spectra of the surface pressure fluctuation and the Aeolian tone show somewhat random nature with a blunt peak. The comparison between the measured and predicted Aeolian tone level from the surface pressure fluctuation shows good agreement for the sub- and super-critical regions but the predicted level is approximately 10 dB lower than the measured level for the trans-critical region.3) Reduction of the Aeolian ToneA half rounded square cylinder shows approximately 10 dB lower Aeolian tone level when the rounded part is faced to the mean flow, compared to the circular cylinder with the same diameter. When a wire of diameter d is wound in spiral with a pitch p,around a circular cylinder of diameter D, the Aeolian tone is considerably decreased when d/D>0.2 and p/D=3. Less

进行了实验研究，以了解从二维方形和圆形的圆柱体与压力传感器嵌入在表面上产生的风音的特性。结果表明：（1）方形阻尼器当攻角为0°或垂直于平均流的平面放置时，风成音的峰值水平最大。攻角在10° ~ 13°时，来自方柱前缘拐角的分离流重新附着在侧面。在此攻角下，表面压力脉动最小，从而风振音也最小。2）圆柱辐射风振音的特征按雷诺数Re可分为三类，即亚临界风振音、亚临界风振音和亚临界风振音（Re<3 × 10 - 6D 15 - 6D 1）、超临界（3 × 10 - 6D 15 - 6D 1 <Re<10 - 6D 16 - 6D 1）和跨临界（Re>10 - 6D 16 - 6D 1）区域。在亚临界区， ...更多信息 气压力脉动沿展向均匀，风音相干性高，Strouhal数为0.2。在超临界区，Strouhal数跃变到0.45，风成音峰值急剧下降。表面压力脉动具有很强的三维性，只有一小部分沿展向与风成线有很强的相干性。在跨临界区，Strouhal数返回到0.2，表面压力波动和风音的频谱显示出一定的随机性与钝峰。根据表面压力波动预测的风成音级与实测的风成音级之间的比较表明，在亚临界区和超临界区，预测的风成音级与实测的风成音级之间具有良好的一致性，但在跨临界区，预测的风成音级比实测的风成音级低约10 dB。与相同直径的圆柱体相比。当直径为d的金属丝以螺距p螺旋缠绕在直径为D的圆柱体周围时，当d/D>0.2且p/D=3时，风音显著降低。少

项目成果

H.Fujita: "Experimental investigations and prediction of aerodynamic sound generated from square cylinders"Proceedings of 4^<th> AIAA/CEAS Aeroacoustics Conference. 2. 942-947 (1998)

H.Fujita：“方形圆柱体产生的空气动力学声音的实验研究和预测”第四届 AIAA/CEAS 气动声学会议论文集。

H.Fujita,A.Sagawa et al: "The Aeolian tone characteristics of a circular cylinder in high Reynolds Number flow"Proceedings of the 5th AIAA/CEAS Aeroacoustics Conference. vol1. 305-310 (1999)

H.Fujita、A.Sakawa 等人：“高雷诺数流中圆柱体的风音特征”第五届 AIAA/CEAS 气动声学会议论文集。

Hajime Fujita, Wei Sha, Hiroshi Furutani and Hideaki Suzuki: "Experimental investigations and prediction of aerodynamic sound generated from square cylinders"Proceedings of 4ィイD1thィエD1 AIAA/CEAS Aeroacoustics Conference, AIAA Paper 98-1849. vol.2. 942-947

Hajime Fujita、Wei Sha、Hiroshi Furutani 和 Hideaki Suzuki：“方形圆柱体产生的空气动力学声音的实验研究和预测”第四届 D1 AIAA/CEAS 气动声学会议记录，AIAA 论文 98-1849。

H.Fujita: "The Aeolian tone and the surface pressure fluctuation in high Re flow"Proceedings of 6^<th> AIAA/CEAS Aeroacoustics Conference. (CD-ROM). (2000)

H.Fujita：“高Re流中的风音和表面压力波动”第6届AIAA/CEAS气动声学会议论文集。

H.Fujita: "The Aeolian tone characteristics of a circular cylinder in high Reynolds number flow"Proceedings of 5^<th> AIAA/CEAS Aeroacoustics Conference. 2. 305-310 (1999)

H.Fujita：“高雷诺数流中圆柱体的风音特征”第 5 届 AIAA/CEAS 气动声学会议论文集。