Airframe-Noise Reduction by Suppressing Near-Wall Turbulent Structures

2011 ◽  
Author(s):  
Seong Ryong Koh ◽  
Wolfgang Schröder ◽  
Matthias Meinke
Keyword(s):  
Noise Reduction ◽  
Turbulent Structures ◽  
Airframe Noise ◽  
Near Wall

Trailing-edge noise reduction of a wing by a surface modification

2021 ◽  
Vol 263 (3) ◽  
pp. 3194-3201
Author(s):  
Varun Bharadwaj Ananthan ◽  
R.A.D. Akkermans ◽  
Dragan Kozulovic
Keyword(s):  
Noise Reduction ◽  
Stochastic Approach ◽  
Slight Reduction ◽  
Noise Sources ◽  
Trailing Edge ◽  
Sound Sources ◽  
Airframe Noise ◽  
Trailing Edge Noise ◽  
Random Particle ◽  
Noise Production

There is an increased emphasis on reducing airframe noise in the last decades. Airframe noise is sound generated by the interaction of a turbulent flow with the aircraft geometry, and significantly contributes to the overall noise production during the landing phase. One examples of airframe noise is the noise generated at a wing's trailing edge, i.e., trailing-edge noise. In this contribution, we numerically explore the local application of riblets for the purpose of trailing-edge noise reduction. Two configurations are studied: i) a clean NACA0012 wing section as a reference, and ii) the same configuration with riblets installed at the wing's aft part. The numerical investigation follows a hybrid computational aeroacoustics approach, where the time-average flow is studied by means of RANS. Noise sources are generated by means of a stochastic approach called Fast Random Particle Mesh method. The results show a deceleration of the flow behind the riblets. Furthermore, the turbulent kinetic energy indicates increased unsteadiness behind the riblets which is shifted away from the wall due to the presence of the riblets. Lastly, the sound sources are investigated by means of the 3D Lamb-vector, which indicates a slight reduction in magnitude near the trailing edge.

Development and Analysis-Driven Optimization of Superelastic Slat-Cove Fillers for Airframe Noise Reduction

AIAA Journal ◽  
2016 ◽  
Vol 54 (3) ◽  
pp. 1078-1094 ◽  
Author(s):  
William D. Scholten ◽  
Darren J. Hartl ◽  
Travis L. Turner ◽  
Reggie T. Kidd
Keyword(s):  
Noise Reduction ◽  
Airframe Noise

scholarly journals Secondary Flow in Smooth and Rough Turbulent Circular Pipes: Turbulence Kinetic Energy Budgets

Fluids ◽  
2021 ◽  
Vol 6 (12) ◽  
pp. 448
Author(s):  
Paolo Orlandi ◽  
Sergio Pirozzoli
Keyword(s):  
Kinetic Energy ◽  
Flow Direction ◽  
Turbulence Kinetic Energy ◽  
Energy Budgets ◽  
Immersed Boundary ◽  
Wall Region ◽  
Turbulent Structures ◽  
Circular Pipes ◽  
Turbulence Kinetic Energy Budget ◽  
Near Wall

Direct Numerical Simulations have been performed for turbulent flow in circular pipes with smooth and corrugated walls. The numerical method, based on second-order finite discretization together with the immersed boundary technique, was validated and applied to various types of flows. The analysis is focused on the turbulence kinetic energy and its budget. Large differences have been found in the near-wall region at low Reynolds number. The change in the near-wall turbulent structures is responsible for increase of drag and turbulence kinetic energy. To investigatselinae the effects of wall corrugations, the velocity fields have been decomposed so as to isolate coherent and incoherent motions. For corrugated walls, we find that coherent motions are strongest for walls covered with square bars aligned with the flow direction. In particular, the coherent contribution is substantial when the bars are spaced apart by a distance larger than their height. Detailed analysis of the turbulence kinetic energy budget shows for this set-up a very different behavior than for the other types of corrugations.

scholarly journals Design of Shape-Adaptive Deployable Slat-Cove Filler for Airframe Noise Reduction

2021 ◽  
pp. 1-17
Author(s):  
Gaetano Arena ◽  
Rainer M. J. Groh ◽  
Alberto Pirrera ◽  
Travis Turner ◽  
William Scholten ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Airframe Noise

POD Investigation of Near-Wall Turbulent Structures

2002 ◽  
Author(s):  
Gaetano Maria Di Cicca ◽  
Angelo Iollo ◽  
Pier Giorgio Spazzini ◽  
Gaetano Iuso ◽  
Michele Onorato
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Particle Image ◽  
Digital Particle Image Velocimetry ◽  
Orthogonal Decomposition ◽  
Wall Region ◽  
Turbulent Structures ◽  
Image Velocimetry ◽  
Proper Orthogonal ◽  
Near Wall

Experimental data of a turbulent boundary layer developing over a flat plate, obtained by Digital Particle Image Velocimetry (DPIV) technique, are analyzed making use of proper orthogonal decomposition (POD). Different POD definitions have been used in order to check their ability in educing the various structures dominating the near wall region. Results show a specific sensitivity depending on the POD definition adopted.

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