A Different Approach to Archimedean Spiral Equation in the Development of a High Frequency Array

Fonseca, William D’Andrea; Ristow, João P.; Sanches, Diogo G.; Gerges, Samir N. Y.

doi:10.4271/2010-36-0541

Cited by 18 publications

(6 citation statements)

References 5 publications

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“…The instrumentation was designed for a flat response from 7 Hz to 40 kHz (1 dB loss) or from 4 Hz to 70 kHz (2 dB loss). The microphone array was designed with a modified spiral geometry 23 to allow measurements at a large frequency band. The 61 microphones were positioned in a 0.8 m × 0.8 m wall as seen in Fig.…”

Section: Phased-array Microphone Measurementsmentioning

confidence: 99%

Improvements of a Hard-Wall Closed Test-Section of a Subsonic Wind Tunnel for Aeroacoustic Testing

Almeida¹,

Catalano²,

Pereira³

2021

The International Journal of Acoustics and Vibration

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For achieving accurate aeroacoustic measurements to the aircraft industry, a low-speed wind tunnel, primarily designed for aerodynamic testing, is modified to provide lower background noise environment. Based on data from single microphone at different wind tunnel locations and microphone phased-array measurements inside the test-section, the main noise sources are identified and feasible alternatives are implemented for reducing the background noise such as new acoustically treated corner-vanes and sidewall lining located upstream the drive system. The acoustically transparent concept for the test-section is also investigated showing promising results for further improvements in the wind tunnel. Results are presented for sound pressure levels from single microphone measurements at different locations in the wind tunnel as well as from the beamforming array inside the test-section. Background noise measurements before and after improvements confirm that the ability of performing aeroacoustic tests has significantly increased with noise reduction of 5 dB inside the test-section.

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Section: Phased-array Microphone Measurementsmentioning

confidence: 99%

Improvements of a Hard-Wall Closed Test-Section of a Subsonic Wind Tunnel for Aeroacoustic Testing

Almeida¹,

Catalano²,

Pereira³

2021

The International Journal of Acoustics and Vibration

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“…A geometria da antena (distribuição dos microfones e abertura) e sua consequente capacidade de supressão de lóbulos laterais (beamwidth e faixa dinâmica), são alvos de intensa pesquisa e inerentes a cada aplicação específica. Um exemplo é a antena utilizada neste trabalho, descrita em Fonseca et al (2010).…”

Section: Técnica De Beamforming E Sua Aplicação Para Caracterização Dunclassified

“…A antena utilizada foi projetada possuindo uma geometria do tipo espiral logarítmica com múltiplos braços, (FONSECA et al, 2010). Sua abertura diametral é de 850 [mm], possuindo 62 microfones distribuídos ao longo de nove braços e sua geometria é otimizada de forma a evitar ao máximo o fenômeno de aliasing espacial (que ocorre quando o comprimento da onda acústica incidente é menor ou igual ao espaçamento regular entre dois microfones da antena).…”

Section: M Munclassified

Efeito aeroacústico de excrescências bidimensionais na cova de um eslate

Amaral¹

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“…The microphone array used consists of 61 G.R.A.S. 46BD microphone sets (which combine a 1/4 in pressure microphone 40BD and a 1/4 in preamplifier 26CB), flush mounted without grid at the test section side-wall, distributed in a modified spiral geometry ( Figure 50) optimized for achieving a high frequency range with minimum beamwidth and side-lobe contamination (FONSECA et al, 2010). Source: Pereira (2018) These microphones have a frequency range of 4 kHz to 70 kHz (±2 dB), a dynamic range of 166 dB, and a calibrated sensitivity of 1.5 to 2.6 mV /P a (obtained with a NC-74 calibrator, which produces a 1.0 kHz, 1.0 P a reference pressure fluctuation).…”

Section: Modelmentioning

confidence: 99%

Dielectric barrier discharge plasma actuators applied to high-lift devices for aerodynamic noise reduction

Silva¹

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scholarships were essential for the realization of this project. To Prof. Dr. Fernando Martini Catalano, for the friendship, support, knowledge and experience shared with me throughout all these years, either as teacher when I was an undergraduate student, either as a supervisor during the execution of the research, or as my supervisor during my teaching internship. To Prof. Dr. José Antônio Garcia Croce, who kindly gave his massive contribution in the implementation and maintenance of the high voltage high frequency AC power supply, without which the experiments of this research could not have been carried out. To the technicians José Claudio Pinto de Azevedo, Mário Sbampato and Osnan Ignacio Faria, for their friendship, solicitude, aid and shared knowledge in the manufacture, assembly, maintenance and operation of the necessary equipment for the experiments. To Gisele Aparecida Poppi Lavadeci, secretary of the Department of Aeronautical Engineering, who was always available to assist me with the bureaucracies, printings or just to talk and take a coffee. To the São Carlos School of Engineering Library staff, for checking the typesetting and the referencing style. To my friends and laboratory colleagues, the engineers

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A Different Approach to Archimedean Spiral Equation in the Development of a High Frequency Array

Cited by 18 publications

References 5 publications

Improvements of a Hard-Wall Closed Test-Section of a Subsonic Wind Tunnel for Aeroacoustic Testing

Improvements of a Hard-Wall Closed Test-Section of a Subsonic Wind Tunnel for Aeroacoustic Testing

Efeito aeroacústico de excrescências bidimensionais na cova de um eslate

Dielectric barrier discharge plasma actuators applied to high-lift devices for aerodynamic noise reduction

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