Inlet Mode Measurements with an Inflow Control Device Microphone Array

Lan, Justin; Premo, John; Sutliff, Daniel L.

doi:10.2514/6.2002-2563

Cited by 13 publications

(8 citation statements)

References 1 publication

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“…These methods tend to use inverse techniques from the measured sound pressure levels on a three-dimensional surface to compute the in-duct modal content. Multiple microphones located precisely on an inflow control device, 9,10 or repositioning of circular array, 11 are required to acquire the three-dimensional pressure field necessary for the computation of modal structure. These methods require hundreds of microphones or repositioning of the array (also requiring, lengthy, discontinuous time samples) to acquire enough spatial points for the computation.…”

Section: Introductionmentioning

confidence: 99%

Interaction and scattered mode measurement in a mixed bypass/core duct with multiple rotating sources

Sutliff

2017

International Journal of Aeroacoustics

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The rotating rake mode measurement system was developed and implemented at the NASA Glenn Research Center in the 1990s to measure turbofan duct acoustic modes. The system is a radial rake with distributed microphones that is inserted into the duct and continuously rotates about the centerline. The rotating rake mode measurement system provides a complete map of the acoustic duct modes present in a ducted fan and has been used on a variety of test articles: from a low-speed concept test rig to full-scale production turbofan engines. Prior rotating rake mode measurement system measurements have occurred in environments with a single rotating source interacting with a stationary source to produce duct modes at the fan rotor harmonics. A recent test of a scale model high-speed research fan in the NASA 9 Â 15 ft Low Speed Wind Tunnel had two rotating sources, a rotor fan and a booster fan, on the same shaft. The interaction of the two rotating sources generated scattering at the harmonic sum and difference tones, and modal scattering at a given fan harmonic. Rotating rake mode measurement system data were acquired from this high-speed fan model which provided a database to allow for validation of the duct mode analysis technique expansion and experimental evidence of the scattering phenomenon. In this paper, modes from the two different sources and associated stationary surfaces from a sample fan condition were reported and compared to analytical predictions, in order to validate the ability of the rotating rake mode measurement system to measure scattered modes. Sample modal content of the booster fan tone and its harmonics tones are presented as well as the sum and difference interaction between the rotor and booster fans.

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Section: Introductionmentioning

confidence: 99%

Interaction and scattered mode measurement in a mixed bypass/core duct with multiple rotating sources

Sutliff

2017

International Journal of Aeroacoustics

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“…Проблеме идентификации модального состава распространяющегося в канале шума вентилятора посвящено большое число экспериментальных исследований (их крат-кий обзор можно найти, например, в работе [19]). Применяемые в этих исследованиях экс-периментальные методы определения модального состава включают измерения микрофон-ными решетками, установленными внутри канала [20][21][22][23] или вне него [23][24][25][26].…”

Section: Introductionunclassified

Application of Planar Beamforming Method to Identification of Spinning Acoustic Modes

Bersenev¹,

Viskova²,

Belyaev³

et al. 2016

PNRPU MB

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“…Схематичное изображение источников шума турбовентиляторного авиационного двигателя и расположения ЗПК [2] Обзор существующих подходов к измерению модального состава в каналах авиационного двигателя можно найти, например, в работе [4]. Стоит отметить, что в настоящий момент методы измерения амплитуд мод в канале с помощью микрофонных решеток, установленных вне его [4][5][6][7][8][9][10][11], хотя и представляют собой перспективное и многообещающее направление исследований, всё еще находятся в стадии отработки. Соответственно, результаты, полученные с помощью этих методов, нуждаются в валидации по измерениям мод с помощью микрофонов, установленных в канале [12], или с помощью вращающейся решетки микрофонов [13].…”

Section: Introductionunclassified

Identification of Spinning Acoustic Modes in Aeroengine Inlet Duct With Circular Microphone Array

Bersenev¹,

Viskova²,

Belyaev³

et al. 2016

PNRPU Aerospace Engineering Bulletin

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Information on the modal content of the sound field in an aeroengine inlet duct is a prerequisite for development of efficient acoustic liners that ensure maximum attenuation of sound during its propagation along the duct. This paper describes the developed test rig for generation of spinning acoustic modes in the duct and validation of mode measurement techniques in the absence of flow. The test rig consists of the full-scale intake of an aircraft engine and 34 acoustic drivers JBL 2451H. To measure the generated modes, an optimized circular microphone array comprising 100 microphones Bruel & Kjaer 4944 was installed in the duct and the modal content of the sound field was measured. The experiments were carried out in the new anechoic chamber of Perm National Research Polytechnic University. It is shown that the circular microphone array allows correct identification of the azimuthal acoustic modes and their combinations. An analysis of the working region (frequencies and mode number range), where the developed test rig can be applied, is provided As a result, this microphone array has been recommended for installation on the aeroengine intake at the open test bench for full-scale tests.

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Inlet Mode Measurements with an Inflow Control Device Microphone Array

Cited by 13 publications

References 1 publication

Interaction and scattered mode measurement in a mixed bypass/core duct with multiple rotating sources

Interaction and scattered mode measurement in a mixed bypass/core duct with multiple rotating sources

Application of Planar Beamforming Method to Identification of Spinning Acoustic Modes

Identification of Spinning Acoustic Modes in Aeroengine Inlet Duct With Circular Microphone Array

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