Skip to main content
×
Home
    • Aa
    • Aa

Aeroacoustic source mechanisms of a wavy leading edge undergoing vortical disturbances

  • Jacob M. Turner (a1) and Jae Wook Kim (a1)
Abstract

High-accuracy numerical simulations are performed to study aeroacoustic source mechanisms of wavy leading edges (WLEs) on a thin aerofoil undergoing vortical disturbances. This canonical study is based on a prescribed spanwise vortex travelling downstream and creating secondary vortices as it passes through the aerofoil’s leading edge. The primary aim of the study is to precisely understand the relationships between the vortex-induced velocity perturbation and the wall pressure fluctuation on the WLE geometry. It is observed that by increasing the size (amplitude) of the WLE the source strength at the peak region is reduced rapidly to a certain point, followed by a saturation stage, while at the root (trough) it remains fairly consistent regardless of the WLE size. This observation is demonstrated to be the consequence of three-dimensional vortex dynamics taking place along the WLE. One of the most profound features is that a system of horseshoe-like secondary vortices are created from the WLE peak region upon the impingement of the prescribed vortex. It is found that the horseshoe vortices produce a significantly non-uniform velocity perturbation in front of the WLE leading to the disparity in the source characteristics between the peak and root. The alterations to the impinging velocity perturbation are carefully analysed and related to the wall pressure fluctuation in this study. In addition, a semi-analytic model based on Biot–Savart’s law is developed to better understand and explain the role of the horseshoe vortex systems and the source mechanisms.

Copyright
Corresponding author
Email address for correspondence: j.w.kim@soton.ac.uk
Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

R. K. Amiet 1975 Acoustic radiation from an airfoil in a turbulent stream. J. Sound Vib. 41, 407420.

L. J. Ayton  & N. Peake 2013 On high-frequency noise scattering by aerofoils in flow. J. Fluid Mech. 734, 144182.

L. J. Ayton  & N. Peake 2015 On high-frequency sound generated by gust-aerofoil interaction in shear flow. J. Fluid Mech. 766, 297325.

V. Clair , C. Polacsek , T. L. Garrec , G. Reboul , M. Gruber  & P. Joseph 2013 Experimental and numerical investigation of turbulence-airfoil noise reduction using wavy edges. AIAA J. 51, 26952713.

W. J. Devenport , J. K. Staubs  & S. A. L. Glegg 2010 Sound radiation from real airfoils in turbulence. J. Sound Vib. 329, 34703483.

I. Evers  & N. Peake 2000 Noise generation by high-frequency gusts interacting with an airfoil in transonic flow. J. Fluid Mech. 411, 91130.

F. E. Fish , L. E. Howle  & M. M. Murray 2008 Hydrodynamic flow control in marine mammals. Integr. Compar. Biol. 48, 788800.

J. Gill , X. Zhang  & P. Joseph 2013 Symmetric airfoil geometry effects on leading edge noise. J. Acoust. Soc. Am. 134, 26692680.

J. Gill , X. Zhang  & P. F. Joseph 2015 Single velocity-component modeling of leading edge turbulence interaction noise. J. Acoust. Soc. Am. 137 (6), 32093220.

M. E. Goldstein 1978 Unsteady vortical and entropic distortions of potential flows around arbitrary obstacles. J. Fluid Mech. 89, 433468.

K. L. Hansen , R. M. Kelso  & B. D. Dally 2011 Performance variations of leading-edge tubercles for distinct airfoil profiles. AIAA J. 49, 185194.

K. L. Hansen , N. Rostamzadeh , R. M. Kelso  & B. B. Dally 2016 Evolution of the streamwise vortices generated between leading edge tubercles. J. Fluid Mech. 788, 730766.

H. Johari , C. Henoch , D. Custodio  & L. Levshin 2007 Effects of leading-edge protuberances on airfoil performance. AIAA J. 45, 26342642.

J. W. Kim 2007 Optimised boundary compact finite difference schemes for computational aeroacoustics. J. Comput. Phys. 225, 9951019.

J. W. Kim 2010 High-order compact filters with variable cut-off wavenumber and stable boundary treatment. Comput. Fluids 39, 11681182.

J. W. Kim 2013 Quasi-disjoint pentadiagonal matrix systems for the parallelization of compact finite-difference schemes and filters. J. Comput. Phys. 241, 168194.

J. W. Kim  & S. Haeri 2015 An advanced synthetic eddy method for the computation of aerofoil-turbulence interaction noise. J. Comput. Phys. 287, 117.

J. W. Kim , S. Haeri  & P. Joseph 2016 On the reduction of aerofoil-turbulence interaction noise associated with wavy leading edges. J. Fluid Mech. 792, 526552.

J. W. Kim , A. S. H. Lau  & N. D. Sandham 2010 Proposed boundary conditions for gust-airfoil interaction noise. AIAA J. 48 (11), 27052710.

J. W. Kim  & D. J. Lee 2000 Generalized characteristic boundary conditions for computational aeroacoustics. AIAA J. 38 (11), 20402049.

J. W. Kim  & D. J. Lee 2004 Generalized characteristic boundary conditions for computational aeroacoustics, part 2. AIAA J. 42 (1), 4755.

J. W. Kim  & P. J. Morris 2002 Computation of subsonic inviscid flow past a cone using high-order schemes. AIAA J. 40 (10), 19611968.

D. Lockard  & P. Morris 1998 Radiated noise from airfoils in realistic mean flows. AIAA J. 36, 907914.

P. Migliore  & S. Oerlemans 2004 Wind tunnel aeroacoustic tests of six airfoils for use on small wind turbines. J. Solar Energy Engng 126, 974985.

D. S. Miklosovic , M. M. Murray , L. E. Howle  & F. E. Fish 2004 Leading-edge tubercles delay stall on humpback whale flippers. Phys. Fluids 16, 3942.

M. R. Myers  & E. J. Kerschen 1995 Influence of incidence angle on sound generation by airfoils interacting with high-frequency gusts. J. Fluid Mech. 292, 271304.

M. R. Myers  & E. J. Kerschen 1997 Influence of camber on sound generation by airfoils interacting with high-frequency gusts. J. Fluid Mech. 353, 221259.

S. Narayanan , P. Chaitanya , S. Haeri , P. Joseph , J. W. Kim  & C. Polacsek 2015 Airfoil noise reductions through leading edge serrations. Phys. Fluids 27, 025109.

D. Rockwell 1998 Vortex-body interactions. Annu. Rev. Fluid Mech. 30, 199229.

M. Roger  & S. Moreau 2010 Extensions and limitations of analytical airfoil broadband noise models. Intl J. Aeroacoust. 9, 273305.

Y. Tsuji , J. H. M. Fransson , P. H. Alfredsson  & A. V. Johansson 2007 Pressure statistics and their scaling in high-Reynolds-number turbulent boundary layers. J. Fluid Mech. 585, 140.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Fluid Mechanics
  • ISSN: 0022-1120
  • EISSN: 1469-7645
  • URL: /core/journals/journal-of-fluid-mechanics
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×
MathJax

Keywords:

Metrics

Full text views

Total number of HTML views: 5
Total number of PDF views: 176 *
Loading metrics...

Abstract views

Total abstract views: 281 *
Loading metrics...

* Views captured on Cambridge Core between 13th December 2016 - 27th June 2017. This data will be updated every 24 hours.