Analysis of radiation patterns of interaction tones generated by inlet rods in the JT15D engine

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

doi:10.2514/6.1979-581

Cited by 18 publications

(5 citation statements)

References 7 publications

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“…Figure 13 shows a comparison of the predicted SPL with the experimental results conducted by Heidmann et al [37] and the computational results computed by Lan et al [34]. The horizontal axis in the figure is the angle from the +𝑥-axial direction.…”

Section: Noise Propagation From the Jt15d Nacellementioning

confidence: 84%

Cartesian Mesh Linearized Euler Equations Solver for Aeroacoustic Problems around Full Aircraft

Fukushima

Sasaki

Nakahashi

2015

International Journal of Aerospace Engineering

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The linearized Euler equations (LEEs) solver for aeroacoustic problems has been developed on block-structured Cartesian mesh to address complex geometry. Taking advantage of the benefits of Cartesian mesh, we employ high-order schemes for spatial derivatives and for time integration. On the other hand, the difficulty of accommodating curved wall boundaries is addressed by the immersed boundary method. The resulting LEEs solver is robust to complex geometry and numerically efficient in a parallel environment. The accuracy and effectiveness of the present solver are validated by one-dimensional and three-dimensional test cases. Acoustic scattering around a sphere and noise propagation from the JT15D nacelle are computed. The results show good agreement with analytical, computational, and experimental results. Finally, noise propagation around fuselage-wing-nacelle configurations is computed as a practical example. The results show that the sound pressure level below the over-the-wing nacelle (OWN) configuration is much lower than that of the conventional DLR-F6 aircraft configuration due to the shielding effect of the OWN configuration.

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Section: Noise Propagation From the Jt15d Nacellementioning

confidence: 84%

Cartesian Mesh Linearized Euler Equations Solver for Aeroacoustic Problems around Full Aircraft

Fukushima

Sasaki

Nakahashi

2015

International Journal of Aerospace Engineering

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“…15 The plane wave mode has a uniform pressure amplitude over the inlet cross section and propagates at all frequencies beaming along the engine axis. 16 With 27 rods, the first-order circumferential spinning modes are generated and the radiation directivity pattern of that mode has a notch along the engine centerline.…”

Section: Active Control Apparatusmentioning

confidence: 99%

Time-averaged active controller for turbofan engine fan noise reduction

Thomas

Burdisso

Lane

1996

Journal of Aircraft

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An active control system has been developed and used experimentally on an operational turbofan engine to reduce inlet tonal noise at the fan blade passage frequency. Both single channel and multichannel systems were tested. The control approach used is the feedforward derivative measurement time-averaged adaptive algorithm. This algorithm is capable of adapting to a nonstationary system, requiring no prior knowledge of the system. A reference sensor mounted in the casing of the fan provides the fan blade passing frequency reference signal to the controller. Microphones with a large sensing area are placed in the acoustic far field of the engine. The control algorithms minimize a cost function, the sum of the error signal mean-square-values, by activating loudspeakers that are mounted around the inlet of the engine. The control signals are obtained by filtering the reference signal with finite impulse response digital filters. The control algorithm finds the optimum filter weights by using statistical estimates of the cost function to be minimized. A single channel control system was tested on an axisymmetric dominant mode case and produced reductions of up to 17 dB at the error microphone. The controller maintained reductions in the fan tone even as the engine speed was increased. In a traverse of the radiated sound field of the engine the fan blade passage tone was reduced over a sector of 30 deg around the error sensor with a considerable spillover increase in the fan tone outside of this sector. Two six-channel control systems were developed and tested on both axisymmetric and spinning mode dominant cases. Reductions of up to 19.7 dB were achieved over large sectors around the error microphones with significantly reduced spillover. Nomenclature C = cost function D = diameter of engine at the fan stage d = disturbance signal = error signal = transfer function = input signal to control sources = adaptive finite impulse response filter coefficients = reference signal = control source output signal = coherence = convergence parameter

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“…For this fan speed, values of rotor tip and duct flow Mach numbers were taken to be 1.00 and 0.25, respectively, based on JT15D data presented in Ref. 12. For a fan speed of 10,500 rpm, the interpretation is not as clear.…”

Section: -1mentioning

confidence: 99%

Turbofan engine blade pressure and acoustic radiation at simulated forward speed

Preisser

Schoenster

Golub

et al. 1983

Journal of Aircraft

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Tests have been conducted on a JT15D-1 turbofan engine both statically and at simulated forward speed in the Ames 12 x 24 m Wind Tunnel. Both far-field acoustic data and unsteady pressure data from transducers mounted on the fan blades were acquired. Results showed a sound power reduction of about 10 dB in the farfield acoustic levels with simulated forward speed over that measured without forward speed. Blade-mounted transducer results showed rotor-turbulence interaction dominated the noise field at very low speeds while an interaction between the rotor and internal struts dominated at higher speeds. Results are presented to show the effects of varying engine revolutions per minute, changing the angle of attack of the engine inlet to tunnel flow, and mounting an aircraft wing to simulate an installation condition on a actual aircraft.

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Analysis of radiation patterns of interaction tones generated by inlet rods in the JT15D engine

Cited by 18 publications

References 7 publications

Cartesian Mesh Linearized Euler Equations Solver for Aeroacoustic Problems around Full Aircraft

Cartesian Mesh Linearized Euler Equations Solver for Aeroacoustic Problems around Full Aircraft

Time-averaged active controller for turbofan engine fan noise reduction

Turbofan engine blade pressure and acoustic radiation at simulated forward speed

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