Recent Studies on Aerodynamic Noise Reduction at RTRI

2012 ◽  
pp. 411-418 ◽  
Author(s):  
T. Takaishi ◽  
N. Yamazaki ◽  
T. Sueki ◽  
T. Uda
Keyword(s):  
Noise Reduction ◽  
Aerodynamic Noise

Numerical study on the airfoil self-noise of three owl-based wings with the trailing-edge serrations

2021 ◽  
pp. 095441002098822
Author(s):  
Dian Li ◽  
Xiaomin Liu ◽  
Lei Wang ◽  
Fujia Hu ◽  
Guang Xi
Keyword(s):  
Flow Field ◽  
Noise Reduction ◽  
Numerical Study ◽  
Barn Owl ◽  
Aerodynamic Noise ◽  
Frequency Noise ◽  
Trailing Edge ◽  
Reduction Mechanisms ◽  
Trailing Edge Serrations ◽  
Bionic Airfoil

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.

Aerodynamic noise reduction by pile fabrics

2010 ◽  
Vol 42 (1) ◽  
pp. 015003 ◽  
Author(s):  
Masaharu Nishimura ◽  
Tomonobu Goto
Keyword(s):  
Noise Reduction ◽  
Aerodynamic Noise

scholarly journals 1002 Aerodynamic noise reduction for aircraft landing gear

2009 ◽  
Vol 2009 (0) ◽  
pp. 321-322
Author(s):  
Kazuhide Isotani ◽  
Kenji Hayama ◽  
Akio Ochi ◽  
Toshiyuki Kumada
Keyword(s):  
Noise Reduction ◽  
Landing Gear ◽  
Aerodynamic Noise ◽  
Aircraft Landing ◽  
Aircraft Landing Gear

scholarly journals Aeroacoustics of Silent Owl Flight

2020 ◽  
Vol 52 (1) ◽  
pp. 395-420 ◽  
Author(s):  
Justin W. Jaworski ◽  
N. Peake
Keyword(s):  
Mathematical Modeling ◽  
Noise Reduction ◽  
Current Knowledge ◽  
Foraging Strategies ◽  
Aerodynamic Noise ◽  
Noise Generation ◽  
Reduction Strategies ◽  
Noise Measurements ◽  
Modeling And Experiments ◽  
Review Current

The ability of some species of owl to fly in effective silence is unique among birds and provides a distinct hunting advantage, but it remains a mystery as to exactly what aspects of the owl and its flight are responsible for this dramatic noise reduction. Crucially, this mystery extends to how the flow physics may be leveraged to generate noise-reduction strategies for wider technological application. We review current knowledge of aerodynamic noise from owls, ranging from live owl noise measurements to mathematical modeling and experiments focused on how owls may disrupt the standard routes of noise generation. Specialized adaptations and foraging strategies are not uniform across all owl species: Some species may not have need for silent flight, or their evolutionary adaptations may not be effective for useful noise reduction for certain species. This hypothesis is examined using mathematical models and borne out where possible by noise measurements and morphological observations of owl feathers and wings.

Aerodynamic noise numerical simulation and noise reduction study on automobile alternator

2017 ◽  
Vol 31 (5) ◽  
pp. 2047-2055 ◽  
Author(s):  
Chunrong Hua ◽  
Yadong Zhang ◽  
Dawei Dong ◽  
Bin Yan ◽  
Huajiang Ouyang
Keyword(s):  
Numerical Simulation ◽  
Noise Reduction ◽  
Aerodynamic Noise

Numerical simulation of aerodynamic noise and noise reduction of range hood

2021 ◽  
Vol 175 ◽  
pp. 107806
Author(s):  
Jia-yu Huang ◽  
Kai Zhang ◽  
Hai-yun Li ◽  
An-ran Wang ◽  
Mingyue Yang
Keyword(s):  
Numerical Simulation ◽  
Noise Reduction ◽  
Aerodynamic Noise

scholarly journals Corrigendum to “A Novel Aerodynamic Noise Reduction Method Based on Improving Spanwise Blade Shape for Electric Propeller Aircraft”

2020 ◽  
Vol 2020 ◽  
pp. 1-1
Author(s):  
Yuhang Wu ◽  
Yan-ting Ai ◽  
Wang Ze ◽  
Tian Jing ◽  
Xiang Song ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Reduction Method ◽  
Aerodynamic Noise ◽  
Blade Shape

Aerodynamic Noise Reduction by Use of a Cooling Fan with Winglets

2003 ◽  
Author(s):  
Atsushi Nashimoto ◽  
Tsuneo Akuto ◽  
Yuichi Nagase ◽  
Nobuyuki Fujisawa
Keyword(s):  
Noise Reduction ◽  
Aerodynamic Noise ◽  
Cooling Fan
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