A compact inflow control device for simulating flight fan noise

Homyak, L.; Mcardle, J. G.; Heidelberg, Laurence J.

doi:10.2514/6.1983-680

Cited by 16 publications

(5 citation statements)

References 2 publications

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“…Acoustic and aerodynamic investigations of these structures showed a significant reduction of inflow turbulence intensities and therefore lowered BPF amplitudes and peak widths (especially at subsonic operating conditions) while broadband noise levels stayed nearly unchanged 1 Accepted manuscript, ?? [3,9,10,8,11,12,13,14,15,16]. This allows to simulate in-flight noise radiation on static test beds which is much less cost intensive than acoustic characterization in fly-over tests.…”

Section: Introductionmentioning

confidence: 99%

Influence of a Turbulence Control Screen on the Aerodynamic and Aeroelastic Behavior of a UHBR Fan

Schneider

Paoletti

Ottavy

et al. 2022

Volume 8A: Structures and Dynamics — Aerodynamics Excitation and Damping; Bearing and Seal Dynamics; Emerging Methods in Engine

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A composite fan stage representative of a modern Ultra High Bypass Ratio (UHBR) architecture has been investigated experimentally on a novel test facility at Ecole Centrale de Lyon. For these experiments, a turbulence control screen (TCS), a hemisphere, consisting of honeycomb and wiremesh panels, was installed in front of the rig in order to ensure homogeneous, disturbance-free inflow conditions. This kind of screen was developed in the early 1970 years to investigate flight-noise on static test beds. Today, they are commonly used in aero-engine and fan tests, because they improve the accuracy of acoustic measurements and provide more reproducible performance tests. However, the influence of such screens has been investigated only from an acoustic point of view in the past. This study presents a back-to-back comparison of measurements with and without the TCS, which allows a characterization of the effects on aerodynamic and aeroelastic behavior of the fan stage. The investigation was carried out for multiple stable operating points on two different speed lines to obtain a global image of the influence at part and design speed. The utilization of steady and unsteady instrumentation in different axial and circumferential duct positions allows a detailed analysis of similarities and differences of the configuration without and with the TCS and provides insight into underlying physical mechanisms.

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Section: Introductionmentioning

confidence: 99%

Influence of a Turbulence Control Screen on the Aerodynamic and Aeroelastic Behavior of a UHBR Fan

Schneider

Paoletti

Ottavy

et al. 2022

Volume 8A: Structures and Dynamics — Aerodynamics Excitation and Damping; Bearing and Seal Dynamics; Emerging Methods in Engine

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“…The ICD was modeled after the NASA Lewis design for a compact ICD. 7 A schematic of the fan and ICD installation is shown in Figure 1. covered with wedges which are 3 feet thick and yields an adsorption coefficient above 99 percent above a frequency of 100 Hz.…”

Section: Fan Modelmentioning

confidence: 99%

Azimuthal patterns of the radiated sound field from a turbofan model

Thomas¹,

Farassat

Clark

et al. 1997

3rd AIAA/CEAS Aeroacoustics Conference

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“…The update equation is (14) where matrix [H] consists of only the diagonal elements of the Hessian matrix [//]. The assumption in this approximation is that the off-diagonal elements are negligible for a quadratic cost function.…”

Section: Pnta Algorithmmentioning

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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A compact inflow control device for simulating flight fan noise

Cited by 16 publications

References 2 publications

Influence of a Turbulence Control Screen on the Aerodynamic and Aeroelastic Behavior of a UHBR Fan

Influence of a Turbulence Control Screen on the Aerodynamic and Aeroelastic Behavior of a UHBR Fan

Azimuthal patterns of the radiated sound field from a turbofan model

Time-averaged active controller for turbofan engine fan noise reduction

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