Aerodynamic Noise Reduction for High-Lift Devices on a Swept Wing Model

Previous publications have summarized that three special morphological structures of owl wing could reduce aerodynamic noise under low Reynolds number flows effectively. However, the coupling noise-reduction mechanism of bionic airfoil with trailing-edge serrations is poorly understood. Furthermore, while the bionic airfoil extracted from natural owl wing shows remarkable noise-reduction characteristics, the shape of the owl-based airfoils reconstructed by different researchers has some differences, which leads to diversity in the potential noise-reduction mechanisms. In this article, three kinds of owl-based airfoils with trailing-edge serrations are investigated to reveal the potential noise-reduction mechanisms, and a clean airfoil based on barn owl is utilized as a reference to make a comparison. The instantaneous flow field and sound field around the three-dimensional serrated airfoils are simulated by using incompressible large eddy simulation coupled with the FW-H equation. The results of unsteady flow field show that the flow field of Owl B exhibits stronger and wider-scale turbulent velocity fluctuation than that of other airfoils, which may be the potential reason for the greater noise generation of Owl B. The scale and magnitude of alternating mean convective velocity distribution dominates the noise-reduction effect of trailing-edge serrations. The noise-reduction characteristic of Owl C outperforms that of Barn owl, which suggests that the trailing-edge serrations can suppress vortex shedding noise of flow field effectively. The trailing-edge serrations mainly suppress the low-frequency noise of the airfoil. The trailing-edge serration can suppress turbulent noise by weakening pressure fluctuation.

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Aerodynamic noise reduction by pile fabrics

Fluid Dynamics Research ◽

10.1088/0169-5983/42/1/015003 ◽

2010 ◽

Vol 42 (1) ◽

pp. 015003 ◽

Cited By ~ 5

Author(s):

Masaharu Nishimura ◽

Tomonobu Goto

Keyword(s):

Noise Reduction ◽

Aerodynamic Noise

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Experimental and Theoretical Investigation of the Supersonic Boundary Layer Stability on the Swept Wing

Siberian Journal of Physics ◽

10.54362/1818-7919-2008-3-3-34-38 ◽

2008 ◽

Vol 3 (3) ◽

pp. 34-38

Author(s):

Sergey A. Gaponov ◽

Yuri G. Yermolaev ◽

Aleksandr D. Kosinov ◽

Nikolay V. Semionov ◽

Boris V. Smorodsky

Keyword(s):

Boundary Layer ◽

Three Dimensional ◽

Leading Edge ◽

Supersonic Boundary Layer ◽

Mean Flow ◽

Swept Wing ◽

Wing Model ◽

Dimensional Boundary ◽

The Stability ◽

Good Agreement

Theoretical and an experimental research results of the disturbances development in a swept wing boundary layer are presented at Mach number М = 2. In experiments development of natural and small amplitude controllable disturbances downstream was studied. Experiments were carried out on a swept wing model with a lenticular profile at a zero attack angle. The swept angle of a leading edge was 40°. Wave parameters of moving disturbances were determined. In frames of the linear theory and an approach of the local self-similar mean flow the stability of a compressible three-dimensional boundary layer is studied. Good agreement of the theory with experimental results for transversal scales of unstable vertices of the secondary flow was obtained. However the calculated amplification rates differ from measured values considerably. This disagreement is explained by the nonlinear processes observed in experiment

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