Predicted and Observed Modal Radiation Patterns from JT15D Engine with Inlet Rods

Heidmann, M. F.; Saule, A. V.; Mcardle, J. G.

doi:10.2514/3.57930

Cited by 7 publications

(10 citation statements)

References 7 publications

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“…6 is the far field distribution for a sharp edged inlet based on Savkar's [15] Wiener-Hopf analytical solution. Savkar's theory was modified for convection effects using a velocity correction factor from reference [16] (equation (8)). As seen in Fig.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…Along the interface separating the interior and exterior regions, the potential in the exterior region g(s) must equal the potential in the interior region. g,(«) = </>/(*) (16) and the impedances at the interface must be equal…”

Section: Fig 5 Theoretical Far Field Spl Directionality Pattern For mentioning

confidence: 99%

“…In this case, the wave equation (4) The previous boundary condition for the external potential gi can be rewritten in terms of <j>* using equation (24). Recall, the potential g, is determined by the finite element solution according to equation (16).…”

Section: Fig 5 Theoretical Far Field Spl Directionality Pattern For mentioning

confidence: 99%

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Finite Element-Integral Acoustic Simulation of JT15D Turbofan Engine

Baumeister

Horowitz

1984

Journal of Vibration and Acoustics

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An .iterative finite element-integral technique is used to predict the sound field radlatedfrom the JTl5D turbofan inlet. The soundfield is divided into two regions: the sound field within and near the inlet which is computed using the finite element method, and the radiation field beyond the inlet which is calculated using an integral solution technique. The velocity potential formulation of the acoustic wave equation was employed in the program. For some single mode JTJ5D datil, the theory and experiment are in good agreement for the far field radiation pattern as well as suppressor attenuation. Also, the computer program is used to simulate flight effects that cannot be performed on a ground static test stand.

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Section: Discussion Of Resultsmentioning

confidence: 99%

Section: Fig 5 Theoretical Far Field Spl Directionality Pattern For mentioning

confidence: 99%

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Finite Element-Integral Acoustic Simulation of JT15D Turbofan Engine

Baumeister

Horowitz

1984

Journal of Vibration and Acoustics

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“…Section 3 reports the results of a series of computer code validation tests. Directivity data from a JT15D engine experiment 1,2 is used for comparison. Section 4 presents computed mean flow data, both with and without forward flight, for the NASA SDT engine inlet.…”

Section: Introductionmentioning

confidence: 99%

“…Acoustic radiation from jet engine inlets has been studied experimentally [1][2][3][4][5][6][7][8][9] , analytically [10][11][12][13] and computationally [14][15][16][17][18][19][20][21][22][23][24][25][26] by a number of investigators in the past. These studies provide a variety of useful and interesting information.…”

Section: Introductionmentioning

confidence: 99%

Physics of Acoustic Radiation from Jet Engine Inlets

Tam

Parrish

Envia

et al. 2012

18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)

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Numerical simulations of acoustic radiation from a jet engine inlet are performed using advanced computational aeroacoustics (CAA) algorithms and high-quality numerical boundary treatments. As a model of modern commercial jet engine inlets, the inlet geometry of the NASA Source Diagnostic Test (SDT) is used. Fan noise consists of tones and broadband sound. This investigation considers the radiation of tones associated with upstream propagating duct modes. The primary objective is to identify the dominant physical processes that determine the directivity of the radiated sound. Two such processes have been identified. They are acoustic diffraction and refraction. Diffraction is the natural tendency for an acoustic wave to follow a curved solid surface as it propagates. Refraction is the turning of the direction of propagation of sound waves by mean flow gradients. Parametric studies on the changes in the directivity of radiated sound due to variations in forward flight Mach number and duct mode frequency, azimuthal mode number, and radial mode number are carried out. It is found there is a significant difference in directivity for the radiation of the same duct mode from an engine inlet when operating in static condition and in forward flight. It will be shown that the large change in directivity is the result of the combined effects of diffraction and refraction.

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Physical processes influencing acoustic radiation from jet engine inlets

et al. 2013

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Numerical simulations of acoustic radiation from a jet engine inlet are performed using advanced computational aeroacoustics algorithms and high-quality numerical boundary treatments. As a model of modern commercial jet engine inlets, the inlet geometry of the NASA Source Diagnostic Test is used. Fan noise consists of tones and broadband sound. This investigation considers the radiation of tones associated with upstream-propagating duct modes. The primary objective is to identify the dominant physical processes that determine the directivity of the radiated sound. Two such processes have been identified. They are acoustic diffraction and refraction. Diffraction is the natural tendency for an acoustic duct mode to follow a curved solid surface as it propagates. Refraction is the turning of the direction of propagation of a duct mode by mean flow gradients. Parametric studies on the changes in the directivity of radiated sound due to variations in forward flight Mach number, duct mode frequency, azimuthal mode number and radial mode number are carried out. It is found there is a significant difference in directivity for the radiation of the same duct mode from an engine inlet when operating in static condition versus one in forward flight. It will be shown that the large change in directivity is the result of the combined effects of diffraction and refraction.

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Predicted and Observed Modal Radiation Patterns from JT15D Engine with Inlet Rods

Cited by 7 publications

References 7 publications

Finite Element-Integral Acoustic Simulation of JT15D Turbofan Engine

Finite Element-Integral Acoustic Simulation of JT15D Turbofan Engine

Physics of Acoustic Radiation from Jet Engine Inlets

Physical processes influencing acoustic radiation from jet engine inlets

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