Aeroacoustic Computations of a Generic Low Boom Concept in Landing Configuration: Part 2 - Airframe Noise Simulations

The aerodynamic noise of landing gears have been widely studied as an important component of the airframe noise. During take-off and landing, there are doors, cavity and fuselage around the landing gear. The noise caused by these aircraft components will interfere with aerodynamic noise generated by the landing gear itself. Hence, paper proposes an Improved Delayed Detached Eddy Simulation (IDDES) method for the investigation of the flow field around a single fuselage nose landing gear (NLG) model and a fuselage nose landing gear model with doors, cavity and fuselage nose (NLG-DCN) respectively. The difference between the two flow fields were analyzed in detail to better understand the influence of these components around the aircraft’s landing gear, and it was found that there is a serious mixing phenomenon among the separated flow from the front doors, the unstable shear layer falling off the leading edge of the cavity and the wake of the main strut which directly leads to the enhancement of the noise levels. Furthermore, after the noise sound waves are reflected by the doors several times, an interference phenomenon is generated between the doors. This interference may be a reason why the tone excited in the cavity is suppressed.

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Trailing-edge noise reduction of a wing by a surface modification

INTER-NOISE and NOISE-CON Congress and Conference Proceedings ◽

10.3397/in-2021-2326 ◽

2021 ◽

Vol 263 (3) ◽

pp. 3194-3201

Author(s):

Varun Bharadwaj Ananthan ◽

R.A.D. Akkermans ◽

Dragan Kozulovic

Keyword(s):

Noise Reduction ◽

Stochastic Approach ◽

Slight Reduction ◽

Noise Sources ◽

Trailing Edge ◽

Sound Sources ◽

Airframe Noise ◽

Trailing Edge Noise ◽

Random Particle ◽

Noise Production

There is an increased emphasis on reducing airframe noise in the last decades. Airframe noise is sound generated by the interaction of a turbulent flow with the aircraft geometry, and significantly contributes to the overall noise production during the landing phase. One examples of airframe noise is the noise generated at a wing's trailing edge, i.e., trailing-edge noise. In this contribution, we numerically explore the local application of riblets for the purpose of trailing-edge noise reduction. Two configurations are studied: i) a clean NACA0012 wing section as a reference, and ii) the same configuration with riblets installed at the wing's aft part. The numerical investigation follows a hybrid computational aeroacoustics approach, where the time-average flow is studied by means of RANS. Noise sources are generated by means of a stochastic approach called Fast Random Particle Mesh method. The results show a deceleration of the flow behind the riblets. Furthermore, the turbulent kinetic energy indicates increased unsteadiness behind the riblets which is shifted away from the wall due to the presence of the riblets. Lastly, the sound sources are investigated by means of the 3D Lamb-vector, which indicates a slight reduction in magnitude near the trailing edge.

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Evaluation of Airframe Noise Reduction Concepts via Simulations Using a Lattice Boltzmann Approach

21st AIAA/CEAS Aeroacoustics Conference ◽

10.2514/6.2015-2988 ◽

2015 ◽

Cited By ~ 12

Author(s):

Ehab Fares ◽

Damiano Casalino ◽

Mehdi R. Khorrami

Keyword(s):

Noise Reduction ◽

Lattice Boltzmann ◽

Airframe Noise

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A Tailored Nonlinear Slat-Cove Filler for Airframe Noise Reduction

Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation ◽

10.1115/smasis2018-8079 ◽

2018 ◽

Author(s):

Gaetano Arena ◽

Rainer Groh ◽

Alberto Pirrera ◽

William Scholten ◽

Darren Hartl ◽

...

Keyword(s):

High Strain ◽

Interaction Analysis ◽

Effective Means ◽

Leading Edge ◽

Structural Behavior ◽

Deployable Structures ◽

Airframe Noise ◽

Structure Interaction ◽

Slat Noise ◽

Displacement Constraints

Exploiting mechanical instabilities and elastic nonlinearities is an emerging means for designing deployable structures. This methodology is applied here to investigate and tailor a morphing component used to reduce airframe noise, known as a slat-cove filler (SCF). The vortices in the cove between the leading edge slat and the main wing are among the important sources of airframe noise. The concept of an SCF was proposed in previous works as an effective means of mitigating slat noise by directing the airflow along an acoustically favorable path. A desirable SCF configuration is one that minimizes: (i) the energy required for deployment through a snap-through event; (ii) the severity of the snap-through event, as measured by kinetic energy, and (iii) mass. Additionally, the SCF must withstand cyclical fatigue stresses and displacement constraints. Both composite and shape memory alloy (SMA)-based SCFs are considered during approach and landing maneuvers because the deformation incurred in some regions may not demand the high strain recoverable capabilities of SMA materials. Nonlinear structural analyses of the dynamic behavior of a composite SCF are compared with analyses of similarly tailored SMA-based SCF and a reference, uniformly thick superelastic SMA-based SCF. Results show that by exploiting elastic nonlinearities, both the tailored composite and SMA designs decrease the required actuation energy compared to the uniformly thick SMA. Additionally, the choice of composite material facilitates a considerable weight reduction where the deformation requirement permits its use. Finally, the structural behavior of the SCF designs in flow are investigated by means of preliminary fluid-structure interaction analysis.

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