Scout‐Vehicle Aerodynamic‐Noise Measurements

David A. Hilton

doi:10.1121/1.2142454

EXPERIMENTAL INVESTIGATION OF TURBULENCE EFFECTS ON AERODYNAMICS NOISE OF CHANNELED NACA 0012 AIRFOIL

Journal of Solar Energy Engineering ◽

10.1115/1.4051409 ◽

2021 ◽

pp. 1-6

Author(s):

Hussein Mohammad ◽

Latif Ibraheem ◽

Viktor Kilchyk ◽

S. O. Bade Shrestha

Keyword(s):

Wind Turbines ◽

Low Frequency ◽

Clean Energy ◽

Low Noise ◽

Aerodynamic Noise ◽

Continuous Exposure ◽

Residential Housing ◽

Technology Advancement ◽

Turbulence Effects ◽

Noise Measurements

Abstract Wind power is rapidly growing worldwide as a renewable and clean energy of choice due to its competitiveness in cost and technology advancement. However, as the wind turbines grow, the aerodynamic noise generated from the rotating blades is becoming a major concern that limits the use of wind turbines, especially near residential housing areas. A significant low sleep quality has been reported within 2km of wind turbines locations that is becoming a problem for wider use of wind energy. [1]. Generally, continuous exposure to 85-90 dBA noise causes permanent hearing loss to human [2]. To reduce the aerodynamic noise, channeled blades were implemented in this work to damp the airflow turbulence that causes the aerodynamic noise. Samples of different diameter sizes and angle of inclinations with respect to the cord have been tested and compared to a regular unchanneled blade. Noise measurements have been carried out using low-frequency microphones with frequencies ranging between 0-10000 Hz. While turbulence measurements were performed using a hot-wire anemometer. The measured noise around the blades ranged between 20-70 dB up to 600 Hz has proven to be directly related to turbulence intensity. The best low noise blade design was recommended based on noise measurement.

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Aeroacoustics of Silent Owl Flight

Annual Review of Fluid Mechanics ◽

10.1146/annurev-fluid-010518-040436 ◽

2020 ◽

Vol 52 (1) ◽

pp. 395-420 ◽

Cited By ~ 13

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.

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Possible Effect of Vehicle Aerodynamic Noise on SAE J57a Passby Noise Measurements

10.4271/762019 ◽

1976 ◽

Cited By ~ 1

Author(s):

L. J. Oswald ◽

R. Hickling

Keyword(s):

Aerodynamic Noise ◽

Noise Measurements

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Scout‐Vehicle Aerodynamic‐Noise Measurements

Sound Its Uses and Control ◽

10.1121/1.2369618 ◽

1963 ◽

Vol 2 (5) ◽

pp. 28-31

Author(s):

David A. Hilton

Keyword(s):

Aerodynamic Noise ◽

Noise Measurements

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Bio-Inspired Aerodynamic Noise Control: A Bibliographic Review

Applied Sciences ◽

10.3390/app9112224 ◽

2019 ◽

Vol 9 (11) ◽

pp. 2224 ◽

Cited By ~ 11

Author(s):

Yong Wang ◽

Kun Zhao ◽

Xiang-Yu Lu ◽

Yu-Bao Song ◽

Gareth J. Bennett

Keyword(s):

Noise Reduction ◽

Noise Control ◽

Experimental Studies ◽

Morphological Characteristics ◽

Leading Edge ◽

Aerodynamic Noise ◽

Trailing Edge ◽

Reduction Techniques ◽

Noise Measurements ◽

Underlying Mechanisms

It is well-known that many species of owl have the unique ability to fly silently, which can be attributed to their distinctive and special feather adaptations. Inspired by the owls, researchers attempted to reduce the aerodynamic noise of aircraft and other structures by learning their noise reduction features from different viewpoints and then using the gained knowledge to develop a number of innovative noise reduction solutions. Although fruitful results have been achieved in the bio-inspired aerodynamic noise control, as far as the authors know, comparatively little work has been done to summarize the main findings and progresses in this area. In this bibliographic survey, we systematically review the progresses and trends of the bio-inspired aerodynamic noise control, including the macroscopic and microscopic morphological characteristics of the owl wing feathers, the noise measurements on both flying birds in the field and prepared wings in the wind tunnel, as well as theoretical, numerical and experimental studies that explored the feasibility, parameter influence, aerodynamic effects and underlying mechanisms of the four main bio-inspired noise reduction techniques, i.e., leading edge serrations, trailing edge serrations, fringe-type trailing edge extensions and porous material inspired noise reduction. Finally, we also give some suggestions for future work.

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