Numerical Investigation of Bio-Inspired Blade Designs at High Reynolds Numbers for Ultra-Quiet Aircraft and Wind Turbines
Numerical Investigation of Bio-Inspired Blade Designs at High Reynolds Numbers for Ultra-Quiet Aircraft and Wind Turbines
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超静音飞机和风力涡轮机高雷诺数仿生叶片设计的数值研究
DOI：
10.2514/6.2017-3502
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发表时间：
2017
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影响因子：
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通讯作者：
W. Devenport
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作者：
Andrew Bodling;B. Agrawal;Anupam Sharma;I. Clark;W. N. Alexander;W. Devenport
本文介绍了受夜猫子羽绒服启发的机翼几何形状的数值分析。目的是了解在之前的实验中通过此类设计观察到的机翼后缘降噪机制。选择 NACA 0012 翼型作为基准翼型。仿生几何形状由一系列“小翼”组成，这些小翼应用在基线翼型后缘附近，并与流动方向对齐。在基线上进行壁分辨大涡模拟 (LES)，对仿生翼型几何形状以及两种几何形状的空气动力学和气动声学性能进行对比。两个模型均在基于弦的雷诺数 Rec = 5 × 105 、流马赫数 M∞ = 0.2 和攻角 α = 0° 下进行仿真。为了与 Rec 高得多（2 M 量级）的实验进行比较，进行了模拟。脱扣是使用几何解析脱扣线实现的，该脱扣线放置在距离翼型前缘 x/c = 0.05 处。与实验数据的比较表明，基线翼型的气动压力系数 (Cp) 分布具有良好的一致性。还发现表面摩擦系数 (Cf) 和 Cp 分布与通过类似地触发边界层获得的 XFOIL 结果非常吻合。基线与翼型后缘附近的仿生翼型之间的表面压力谱比较表明，高频时小翼的压力谱减少了 3 dB 量级。研究了降噪机制的两种假设：（1）展向相关长度减小，（2）源“散射边缘”分离距离增加。模拟显示两种几何形状之间的展向相干性差异不显着，但清楚地表明小翼将湍流涡流提升远离机翼后缘，从而降低了散射效率。学科空气动力学和流体力学|航空航天工程|结构和材料评论 这是 Andrew Bodling、Bharat R. Agrawal、Anupam Sharma、Ian Clark、William N. Alexander 和 William J. Devenport 出版的会议手稿。 (2017)“超静音飞机和风力涡轮机高雷诺数仿生叶片设计的数值研究”，第 23 届 AIAA/CEAS 气动声学会议，AIAA 航空论坛，(AIAA 2017-3502)。 DOI：10.2514/6.2017-3502。经许可发布。作者：Andrew Bodling、Bharat Raj Agrawal、Anupam Sharma、Ian Clark、W. Nathan Alexander 和 William Devenport 本会议论文集可在爱荷华州立大学数字存储库中获取：https://lib.dr.iastate.edu/aere_conf/41 超静音飞机和风力涡轮机高雷诺数仿生叶片设计的数值研究 Andrew Bodling、Bharat Raj Agrawal, Anupam Sharma Department of Aerospace Engineering, Iowa State University, Ames, IA, USA, 50011。Ian Clark, W. Nathan Alexander, and, William Devenport Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061。本文介绍了受夜猫子羽绒服启发的翼型几何形状的数值分析。目的是了解在之前的实验中通过此类设计观察到的机翼后缘降噪机制。选择 NACA 0012 翼型作为基准翼型。仿生几何形状由一系列“小翼”组成，这些小翼应用在基线翼型后缘附近，并与流动方向对齐。在基线上进行壁分辨大涡模拟 (LES)，对仿生翼型几何形状以及两种几何形状的空气动力学和气动声学性能进行对比。两个模型均在基于弦的雷诺数 Rec = 5 × 10、流马赫数 M∞ = 0.2 和攻角 α = 0° 下进行仿真。为了与 Rec 高得多（2 M 量级）的实验进行比较，进行了模拟。脱扣是使用几何解析脱扣线实现的，该脱扣线放置在距机翼前缘 x/c = 0.05 处。与实验数据的比较表明，基线翼型的气动压力系数 (Cp) 分布具有良好的一致性。还发现表面摩擦系数 (Cf) 和 Cp 分布与通过类似地触发边界层获得的 XFOIL 结果非常吻合。表面压力谱 *研究生，1200 Howe Hall, Ames IA, 50011。abodling@iastate.edu。 AIAA 学生会员 博士学生，地址：1200 Howe Hall, Ames IA, 50011。bharatr@iastate.edu。 AIAA 学生会员。助理教授，2341 Howe Hall，Ames，IA，50011。sharma@iastate.edu。 AIAA高级会员。 §博士学生，clarki91@vt.edu。 AIAA 学生会员。 ¶助理教授，alexande@vt.edu。美国汽车协会会员。教授，McBryde Hall，RM 660E,225 Stanger St., Blacksburg, VA 24061。devenport@vt.edu。 AIAA 副研究员。美国航空航天研究所对基线与翼型后缘附近的仿生翼型进行的 18 项比较中的 1 项显示，尾翼在高频下减少了 3 dB 量级。研究了降噪机制的两种假设：（1）展向相关长度减小，（2）源“散射边缘”分离距离增加。模拟显示两种几何形状之间的展向相干性差异不显着，但清楚地表明小翼将湍流涡流提升远离机翼后缘，从而降低了散射效率。
This paper presents numerical analysis of an airfoil geometry inspired by the down coat of the night owl. The objective is to understand the mechanisms of airfoil trailing edge noise reduction that has been observed with such designs in previous experiments. The NACA 0012 airfoil is selected as the baseline airfoil. The bioinspired geometry consists of an array of “finlets” that are applied near the trailing edge of the baseline airfoil and are aligned with the flow direction. Wall-resolved large eddy simulations (LES) are performed over the baseline and the bioinspired airfoil geometries and the aerodynamic and aeroacoustic performance of the two geometries are contrasted. Both models are simulated at chordbased Reynolds number Rec = 5 × 105 , flow Mach number, M∞ = 0.2, and angle of attack, α = 0◦ . The simulations are tripped in order to compare with experiments that are at much higher Rec (of the order of 2 M). Tripping is achieved using a geometryresolved trip wire, placed at x/c = 0.05 from the airfoil leading edge. Comparisons with experimental data show good agreement for aerodynamic pressure coefficient (Cp) distribution for the baseline airfoil. Skin friction coefficient (Cf ) and Cp distributions are also found to compare well with XFOIL results obtained by similarly tripping the boundary layer. Surface pressure spectra comparisons between the baseline and the bioinspired airfoil near the airfoil trailing edge show reductions with the finlets of the order of 3 dB at high frequencies. Two hypotheses of noise reduction mechanisms are investigated: (1) reduction in spanwise correlation length, and (2) increase in source-’scattering edge’ separation distance. The simulations show insignificant difference in spanwise coherence between the two geometries, but clearly show that the finlets lift turbulence eddies away from the airfoil trailing edge hence reducing scattering efficiency. Disciplines Aerodynamics and Fluid Mechanics | Aerospace Engineering | Structures and Materials Comments This is a manuscript of a proceeding published as Andrew Bodling, Bharat R. Agrawal, Anupam Sharma, Ian Clark, William N. Alexander, and William J. Devenport. (2017) "Numerical Investigation of Bio-Inspired Blade Designs at High Reynolds Numbers for Ultra-Quiet Aircraft and Wind Turbines", 23rd AIAA/CEAS Aeroacoustics Conference, AIAA AVIATION Forum, (AIAA 2017-3502). DOI: 10.2514/6.2017-3502. Posted with permission. Authors Andrew Bodling, Bharat Raj Agrawal, Anupam Sharma, Ian Clark, W. Nathan Alexander, and William Devenport This conference proceeding is available at Iowa State University Digital Repository: https://lib.dr.iastate.edu/aere_conf/41 Numerical Investigation of Bioinspired Blade Designs at High Reynolds Numbers for Ultra-Quiet Aircraft and Wind Turbines Andrew Bodling , Bharat Raj Agrawal, Anupam Sharma Department of Aerospace Engineering, Iowa State University, Ames, IA, USA, 50011. Ian Clark , W. Nathan Alexander, and, William Devenport Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061. This paper presents numerical analysis of an airfoil geometry inspired by the down coat of the night owl. The objective is to understand the mechanisms of airfoil trailing edge noise reduction that has been observed with such designs in previous experiments. The NACA 0012 airfoil is selected as the baseline airfoil. The bioinspired geometry consists of an array of “finlets” that are applied near the trailing edge of the baseline airfoil and are aligned with the flow direction. Wall-resolved large eddy simulations (LES) are performed over the baseline and the bioinspired airfoil geometries and the aerodynamic and aeroacoustic performance of the two geometries are contrasted. Both models are simulated at chordbased Reynolds number Rec = 5 × 10, flow Mach number, M∞ = 0.2, and angle of attack, α = 0◦. The simulations are tripped in order to compare with experiments that are at much higher Rec (of the order of 2 M). Tripping is achieved using a geometry-resolved trip wire, placed at x/c = 0.05 from the airfoil leading edge. Comparisons with experimental data show good agreement for aerodynamic pressure coefficient (Cp) distribution for the baseline airfoil. Skin friction coefficient (Cf) and Cp distributions are also found to compare well with XFOIL results obtained by similarly tripping the boundary layer. Surface pressure spectra *Graduate student, 1200 Howe Hall, Ames IA, 50011. abodling@iastate.edu. AIAA Student Member Ph.D. student, 1200 Howe Hall, Ames IA, 50011. bharatr@iastate.edu. AIAA Student Member. Assistant Professor, 2341 Howe Hall, Ames, IA, 50011. sharma@iastate.edu. AIAA Senior Member. §Ph.D. student, clarki91@vt.edu. AIAA Student Member. ¶Assistant Professor, alexande@vt.edu. AIAA Member. Professor, McBryde Hall, RM 660E,225 Stanger St., Blacksburg, VA 24061. devenport@vt.edu. AIAA Associate Fellow. 1 of 18 American Institute of Aeronautics and Astronautics comparisons between the baseline and the bioinspired airfoil near the airfoil trailing edge show reductions with the finlets of the order of 3 dB at high frequencies. Two hypotheses of noise reduction mechanisms are investigated: (1) reduction in spanwise correlation length, and (2) increase in source-’scattering edge’ separation distance. The simulations show insignificant difference in spanwise coherence between the two geometries, but clearly show that the finlets lift turbulence eddies away from the airfoil trailing edge hence reducing scattering efficiency.