Quadrupole noise generated from a low-speed aerofoil in near- and full-stall conditions

Author:

Turner Jacob M.ORCID,Kim Jae WookORCID

Abstract

In this paper, direct numerical simulations are performed for low-speed flows past a NACA0012 aerofoil at high incidence angles. The aim is to investigate the significance of quadrupole noise generated due to separated shear layers, in comparison to dipole noise emanating from the aerofoil surface. The two different noise components (dipole and quadrupole) are calculated by using the Ffowcs Williams & Hawkings method in two different approaches: one with a solid surface and another with a permeable surface. The quadrupole noise is then estimated approximately by taking the relative difference between the two. The current study provides detailed comparisons between the quadrupole and dipole noise components at various observer locations in a wide range of frequencies. The comparisons are also made in terms of Mach number scaling, which differs significantly from theoretical predictions and changes rapidly with frequency. Additionally, pre-, near- and full-stall conditions are cross-examined, which reveals significant differences in the quadrupole contributions, including changes in the major source locations and frequencies. It is found that the inclusion of the quadrupole sources gives rise to the predicted noise power level at all frequencies (varying between 2 and 10 dB for an observer above the aerofoil) compared to the dipole-only case. The quadrupole contribution is far from negligible even at the low subsonic speeds (Mach 0.3 and 0.4) when aerofoil stall occurs.

Funder

Engineering and Physical Sciences Research Council

Publisher

Cambridge University Press (CUP)

Subject

Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics

Reference31 articles.

1. On the differences in noise predictions based on solid and permeable surface Ffowcs Williams–Hawkings integral solutions

2. Bertagnolio, F. , Aagaard Madsen, H. , Fischer, A. & Bak, C. 2015 Experimental characterization of stall noise toward its modelling. In Proceedings of the 6th International Conference on Wind Turbine Noise. Glasgow, UK.

3. Brooks, T.F. , Pope, D.S. & Marcolini, M.A. 1953 Airfoil self-noise and prediction. NASA reference publication 1218.

4. Generalized Characteristic Boundary Conditions for Computational Aeroacoustics, Part 2

5. On the precise implications of acoustic analogies for aerodynamic noise at low Mach numbers

Cited by 15 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3