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Letteratura scientifica selezionata sul tema "NOISE LANDING GEAR"

Autore: Grafiati
Pubblicato: 11 settembre 2023

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Articoli di riviste sul tema "NOISE LANDING GEAR"

1

Mu, Yongfei, Jie Li, Wutao Lei e Daxiong Liao. "The effect of doors and cavity on the aerodynamic noise of fuselage nose landing gear". International Journal of Aeroacoustics 20, n. 3-4 (15 marzo 2021): 345–60. http://dx.doi.org/10.1177/1475472x211003297.

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Abstract (sommario):
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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2

Kopiev, Victor, Ivan Belyaev, Mikhail Zaytsev e Kun Zhao. "An Aeroacoustic Study of Full-Scale and Small-Scale Generic Landing Gear Models with Identical Geometry". Applied Sciences 13, n. 4 (10 febbraio 2023): 2295. http://dx.doi.org/10.3390/app13042295.

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Abstract (sommario):
The paper reports on the results of acoustic measurements of full-scale and small-scale generic landing gear models, which have identical geometry and differ only by their scales. The large-scale landing gear models were simplified and lack small geometric details, which for the first time allows their results to be directly compared with those for the small-scale models of the same geometry. It is shown that after application of the scaling procedure to their noise spectra, the normalized results for broadband noise of the landing gear models of different scales are in good agreement with each other. This result seems to support the feasibility of developing technologies for low-frequency noise reduction of landing gears based on small-scale tests and allowing refinement of semi-empirical models of noise prediction for different landing gear elements.
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3

Yang, Guang Jun, Jian Jun Liu e Jing Sun. "Computational Aeroacoustic Simulation of Landing Gear". Applied Mechanics and Materials 421 (settembre 2013): 110–15. http://dx.doi.org/10.4028/www.scientific.net/amm.421.110.

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Abstract (sommario):
RANS / NLAS numerical simulation method is adopted in this paper to carry out study on the aerodynamic noise analysis of basic landing gear configuration. Reynolds average N-S equation is solved with nonlinear turbulence model to establish the landing gear initial flow field, based on which, the NLAS (nonlinear acoustic solver) processed the turbulence fluctuation reconstruction to obtain the near-field acoustic characteristics of landing gear. Combined with the flow characteristics and the associated noise spectrum analysis, aerodynamic noise characteristics of landing gear are achieved. The work in this paper can provide useful research foundation on the following noise reduction design of landing gear.
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4

TIAN, Siyuan, Peixun YU, Junqiang BAI, Xiaofeng REN, Anyu BAO e Xiao HAN. "Analysis of aerodynamic and aeroacoustics of full scale landing gear". Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 40, n. 5 (ottobre 2022): 953–61. http://dx.doi.org/10.1051/jnwpu/20224050953.

Testo completo
Abstract (sommario):
The aerodynamic noise of a landing gear is an important source of airframe noise. The analysis of its noise characteristics plays an important role in the design of a low-noise landing gear. Based on the FL-52 acoustic wind tunnel test technology, the coupled scale adaptive model and the acoustic disturbance equation, the results on aerodynamic noise of a full-scale landing gear model are analyzed. The high-fidelity model includes transverse strut, torsion arm, piston rod, wheel and other parts. The characteristics of static pressure distribution, power spectrum density of pulsating pressure, aerodynamic noise source distribution and directivity of overall sound pressure level are analyzed. The noise characteristics of the far-field microphone are compared with the local microphone installed in the wheel cavity. In this way, we characterize the directivity of pure tone in the wheel cavity and understand its contribution to the far-field noise. The results show that the aerodynamic noise of the landing gear can be quantified accurately by the hybrid numerical method. The pure tone has two frequencies inside and outside the wheel of the landing gear: 560 Hz and 960 Hz. The peak of the loudest sound pressure level reaches 136 dB, and the pure tone radiates to the surface of the non-separation area of the wheel of the landing gear. However, the wall pressure spectrum of the points located in the turbulence region shows a wide-frequency characteristic, and there is no obvious pure tone. From the point of view of the far-field noise directivity, the forward noise of the landing gear is larger than the rear noise, and there is a small overall sound pressure level area at the points of 65 and 110 degrees respectively. When the monitoring points are far away, the far-field noise of the landing gear shows the characteristics of wide frequency, and no obvious pure tone appears. The method can provide the technical support for predicting the aeroacoustics of a landing gear and designing a low-noise land gear.
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5

Hu, Ning, Xuan Hao, Cheng Su, Wei Min Zhang e Han Dong Ma. "Near-Field Noise Prediction for Landing Gear Based on Detached Eddy Simulations". Applied Mechanics and Materials 472 (gennaio 2014): 105–10. http://dx.doi.org/10.4028/www.scientific.net/amm.472.105.

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Abstract (sommario):
A four-wheel rudimentary landing gear is studied numerically by detached eddy simulation (DES) based on the Spalart-Allmaras turbulence model. The surface sound pressure level and sound pressure spectra are calculated using the obtained unsteady flow field. The investigation shows that DES can describe the steady and unsteady properties in the flow around rudimentary landing gear. It can give reasonable results since the flow around the landing gear is a massive separated flow. The results prove the feasibility of DES type methods in massive separated unsteady flow field and aerodynamic noise prediction for landing gear, and can be used in the study of landing gear noise reduction.
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6

Merino-Martínez, Roberto, Eleonora Neri, Mirjam Snellen, John Kennedy, Dick G. Simons e Gareth J. Bennett. "Multi-Approach Study of Nose Landing Gear Noise". Journal of Aircraft 57, n. 3 (maggio 2020): 517–33. http://dx.doi.org/10.2514/1.c035655.

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7

Liang, Yong, Kun Zhao, Yingchun Chen, Longjun Zhang e Gareth J. Bennett. "An Experimental Characterization on the Acoustic Performance of Forward/Rearward Retraction of a Nose Landing Gear". International Journal of Aerospace Engineering 2019 (4 luglio 2019): 1–11. http://dx.doi.org/10.1155/2019/4135094.

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Abstract (sommario):
The modern undercarriage system of a large aircraft normally requires the landing gear to be retractable. The nose landing gear, installed in the front of the fuselage, is retracted either forward or rearward. In the forward/rearward retraction system, the landing gear is normally installed to the trailing/leading side of the bay. When the incoming flow passes the landing gear as well as the bay, the installation that corresponds to the forward/rearward retraction system has a significant impact on the coupling flow and the associated noise of the landing gear and the bay. In this paper, acoustic performance of the forward/rearward retraction of the nose landing gear was discussed based on experiment. The landing gear bay was simplified as a rectangular cavity, and tests were conducted in an aeroacoustics wind tunnel. The cavity oscillation was first analyzed with different incoming speeds. Then, the landing gear model was installed close to the trailing and the leading side of the cavity, respectively. It was observed that installation close to the leading side can help disturb the shear layer so as to suppress the oscillation, while the trailing one can make the landing gear itself produce lower noise. Accordingly, conclusions on the acoustic performance of the forward/rearward retraction of the nose landing gear are made.
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8

Long, Shuang Li, Hong Nie e Xin Xu. "Aeroacoustic Study on a Simplified Nose Landing Gear". Applied Mechanics and Materials 184-185 (giugno 2012): 18–23. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.18.

Testo completo
Abstract (sommario):
Simulation analysis and experiment research are performed on the aeroacoustic noise of a landing gear component in this paper. Detached Eddy Simulation (DES) is used to produce the flow field of the model. The Ffowcs-Williams/Hawkings (FW-H) equation is used to calculate the acoustic field. The sound field radiated from the model is measured in the acoustic wind tunnel. A comparison shows that the simulation results agree well with the experiment results under the acoustic far field condition. The results show that the noise radiated from the model is broadband noise. The directivity of the noise source is like a type of dipole. The wheel is the largest contributor and the strut is the least contributor to the landing gear noise. The results can provide some reference for low noise landing gear design.
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9

Bennett, Gareth J., Eleonora Neri e John Kennedy. "Noise Characterization of a Full-Scale Nose Landing Gear". Journal of Aircraft 55, n. 6 (novembre 2018): 2476–90. http://dx.doi.org/10.2514/1.c034750.

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10

Huang, Longlong, Kun Zhao, Junbiao Liang, Victor Kopiev, Ivan Belyaev e Tian Zhang. "A Numerical Study of the Wind Speed Effect on the Flow and Acoustic Characteristics of the Minor Cavity Structures in a Two-Wheel Landing Gear ". Applied Sciences 11, n. 23 (26 novembre 2021): 11235. http://dx.doi.org/10.3390/app112311235.

Testo completo
Abstract (sommario):
The landing gear is widely concerned as the main noise source of airframe noise. The flow characteristics and aerodynamic noise characteristics of the landing gear were numerically simulated based on Large Eddy Simulation and Linearized Euler Equation, and the feasibility of the simulation model was verified by experiments. Then the wind speed effect on the flow and acoustic characteristics of the minor cavity structures in a two-wheel landing gear were analyzed. The results show that the interaction of vortices increases with the increase of velocity at the brake disc, resulting in a slight increase in the amplitude of pressure fluctuation at 55 m·s−1~75 m·s−1. With the increase of speed, the obstruction at the lower hole of torque link decreases, and many vortical structures flow out of the lower hole and are dissipated, so that the pressure fluctuation amplitude of 75 m·s−1 almost does not increase relative to 55 m·s−1. The contribution of each part in the landing gear to the overall noise is as follows: shock strut > tire > torque link > brake disc. At the speed of 34 m·s−1~55 m·s−1, the contribution of each component to the total noise increases with the increase of speed, and the small components such as torque link and brake disc contribute more to the total noise. At the speed of 55 m·s−1~75 m·s−1, the increase of overall noise mainly comes from the main components such as shock strut and tire, and the brake disc and torque link contribute very little to the overall noise. It provides a reference for the further noise reduction optimization design of the landing gear.
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Tesi sul tema "NOISE LANDING GEAR"

1

Liu, Wen. "Numerical investigation of landing gear noise". Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/210942/.

Testo completo
Abstract (sommario):
Noise generated by aircraft landing gears is a major contributor to the overall airframe noise of a commercial aircraft during landing approach. Because of the complex geometry of landing gears, the prediction of landing gear noise has been very difficult and currently relies on empirical tools, which have limited reliability and flexibility on the applications of unconventional gear architectures. The aim of this research is to develop an efficient and accurate numerical method to investigate the generation and far field radiation of the landing gear noise. In this thesis a hybrid approach is developed that combines near field flow computations with an integral radiation model to enable the far field signal to be evaluated without the need to directly resolve the propagation of the acoustic waves. The recent advances in the CAA methods are implemented with high-order finite difference compact schemes and a characteristics-based multi-block interface treatment. Aerodynamic noise from a generic two-wheel landing gear model, provided by Airbus LAGOON (landing gear noise database for CAA validation) program, is predicted by using the hybrid approach and compared with the LAGOON database. The unsteady flow field is computed by using a compressible Navier-Stokes solver based on high-order finite difference schemes. The calculated time history of surface data is used in a FW-H solver to predict the far field noise levels. Both aerodynamic and aeroacoustic results are compared with wind tunnel measurements in good agreement. Individual contributions from three components, i.e. wheels, axle and strut of the landing gear model are also investigated to identify the major noise source component. It is found that strong flow-body interaction noise is generated by the flow separated from tire rim impinging on the axle. Based on the same landing gear model, the comparison study using conventional CFD solver FLUENT is performed with a second-order Navier-Stokes finite volume solver to compute the unsteady near field flow and the built-in FW-H solver to calculate the far field sound propagation. The comparison suggests that although conventional CFD method can obtain good timeaveraged aerodynamic results, its ability of predicting sound radiation is limited by the inherent low-order numerical discretizations. The aerodynamic noise from the isolated undercarriage wheel with detailed hub configuration is also investigated using FLUENT. The asymmetric phenomenon in the mean flow is discovered in the wake region of the wheel, which contributes to a positive lift force for the wheel. It is predicted that the isolated wheel radiates relatively strong noise to the sides with several strong tonal noise.
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2

Wang, Meng. "High-order numerical investigations into landing gear wheel noise". Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/416431/.

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Abstract (sommario):
Wheels are significant landing gear noise sources. In this project, high-order numerical simulations were conducted to investigate the landing gear wheel noise generation mechanisms and noise reduction treatments. The high-order solver solves the Navier-Stokes equations on multiblock structured grids. In this work, a modified solver was developed based on cell-centred formulation, which can provide more accurate solutions than cell-vertex space. This solver applies a finite-difference scheme at interior control points and at block interfaces with smooth grid metrics. At discontinuous block interfaces, a finite-volume method is employed as an interface condition. Two sets of interpolation schemes were developed to apply the finite volume method. This cell-centred high-order solver is accurate and robust for aeroacoustic simulations of complex geometries. The numerical solver was applied to investigate the major noise sources of a 33% scaled isolated landing gear wheel by simulating three different wheel configurations using a hybrid CFD/FW-H approach. The configurations simulated include a baseline wheel with a hub cavity and two rim cavities. Two additional simulations were performed; one with the hub cavity covered and the other with both the hub cavity and rim cavities covered. The tyre is the main low frequency noise source and shows a lift dipole and side force dipole pattern depending on the frequency. The hub cavity is identified as the dominant middle frequency noise source and radiates in a frequency range centred around the first and second depth modes of the cylindrical hub cavity. The rim cavities are the main high-frequency noise sources. The largest noise reduction is achieved by covering both hub and rim cavities in the hub side direction. Simulations of two wheels in tandem were also performed to study the wheel interaction noise at different angles of attack. The interaction noise is greatest at zero angle of attack, radiating towards the two sideline directions with a spectral peak at StW = 0.19, based on the width of the wheel. The dominant interaction noise source is the upstream shoulder of the downstream wheel. The wheel interaction noise is reduced at positive angles of attack, as less of the downstream wheel is immersed in the wake of the upstream wheel. A gap fairing was simulated, and it can significantly reduce the interaction noise by eliminating large-scale turbulent structures in the gap region. The downstream wheel hub and rim cavities do not have large contributions to the far-field acoustics.
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3

Boorsma, Koen. "Aeroacoustic control of landing gear noise using perforated fairings". Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/66081/.

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Abstract (sommario):
A study was performed to investigate and optimize the application of perforated fairings for landing gear noise control. The sparse knowledge about this new subject has necessitated a more fundamental study involving a basic fairing-strut configuration, followed by wind tunnel tests on a simplified landing gear configuration incorporating perforated fairings. For the basic configuration, various exchangeable perforated half-cylindrical shells shrouding a circular cylinder were the subject of aerodynamic and acoustic tests. A qualitative and quantitative description has been given of the influence of perforated fairings on time averaged and unsteady flow and the related acoustics. The bled air through the shell prevents the formation of large scale vortices associated with the shell and thereby reduces low frequency noise. However, a test with a noisy H-beam replacing the circular cylinder has indicated that increasing porosity can result in adverse noise effects due to the bled mass flow washing the strut. Shearing flow past the perforate has been shown to create adverse self-noise of which both intensity and spectral content are dictated by the local velocity past the perforate. The application of perforated fairings to the simplified landing gear model reduces the low frequency noise introduced by the solid fairings to values below the baseline landing gear configuration in both side and ground view directions. Exposing the perforate outside the stagnation area does not yield extra noise reduction but introduces perforate self-noise. The synthesis of the conducted studies has shed new light on the application of perforated fairings for landing gear noise control. In particular the effects of porosity and perforation location have been clarified. However more research is needed for further optimization of these parameters.
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4

Fattah, Ryu. "The noise generation by a main landing gear door". Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/390837/.

Testo completo
Abstract (sommario):
Experimental measurements and numerical simulations were conducted on a simplified main landing gear model that consists of a leg-door, and a main strut in a parallel configuration. The effects of varying the leg-door angle of attack, and the gap distance between the two elements, were initially studied by two-dimensional and low-order numerical simulations, using the unsteady Reynolds-Averaged Navier-Stokes equations. The strut diameter was specified to the same diameter as a full-scale main landing gear, and simulated under a free-stream Mach number of 0.2, and a Reynolds number based on the cylinder diameter of 1:7 x 106. Further three-dimensional and high-order numerical simulations were conducted on models with a constant gap distance of 8.7% of the cylinder diameter. The high-order solver evaluates the three-dimensional Navier-Stokes equations in the full-conservation form, with the Zonal Detached-Eddy Simulation model. The fidelity of the numerical solver was improved in two parts. Firstly, an Eigenvalue analysis for a multiple-block environment was developed to optimise the combination of spatial and filtering schemes for maximum grid resolution that is numerically stable. Secondly, a grid quality metric, which correlates strongly to the solution accuracy, was developed. A validation database of experimental measurements on a tripped 26% scale interaction model, at a free-stream Mach number of 0.09, and a Reynolds number based on the cylinder diameter of 2 x 105, was developed at the 2:1 m x 1:5 m wind tunnel at the University of Southampton. The experimental and numerical results show that the wake generated by the interaction model is dominated by low frequencies that correspond to the vortex shedding modes of the cylinder, and the door. As the door angle is increased from 0 to 10.7 degrees, the intensity of the cylinder shedding mode decreased. The sound pressure levels of the radiated noise were calculated using the FW-H method. The dominant noise source is a compact dipole, which reduced in strength as the door angle was increased.
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5

Lopes, Leonard Vincent Brentner Kenneth S. "A new approach to complete aircraft landing gear noise prediction". [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4401/index.html.

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6

Ravetta, Patricio A. "LORE Approach for Phased Array Measurements and Noise Control of Landing Gears". Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29975.

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Abstract (sommario):
A novel concept in noise control devices for landing gears is presented. These devices consist of elastic membranes creating a fairing around the major noise sources. The purpose of these devices is to reduce wake interactions and to hide components from the flow, thus, reducing the noise emission. The design of these fairings was focused on the major noise sources identified in a 777 main landing gear. To find the major noise sources, an extensive noise source identification process was performed using phased arrays. To this end, phased array technologies were developed and a 26%-scale 777 main landing gear model was tested at the Virginia Tech Stability Wind Tunnel. Since phased array technologies present some issues leading to misinterpretation of results and inaccuracy in determining actual levels, a new approach to the deconvolution of acoustic sources has been developed. The goal of this post-processing is to "simplify" the beamforming output by suppressing the sidelobes and reducing the sources mainlobe to a small number of points that accurately identify the noise sources position and their actual levels. To this end, the beamforming output is modeled as a superposition of "complex" point spread functions and a nonlinear system of equations is posted. Such system is solved using a new 2-step procedure. In the first step an approximated linear problem is solved, while in the second step an optimization is performed over the nonzero values obtained in the previous step. The solution to this system of equations renders the sources position and amplitude. The technique is called: noise source Localization and Optimization of Array Results (LORE). Numerical simulations as well as sample experimental results are shown for the proposed post-processing.
Ph. D.
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7

Remillieux, Marcel Christophe. "Aeroacoustic Study of a Model-Scale Landing Gear in a Semi-Anechoic Wind Tunnel". Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/31674.

Testo completo
Abstract (sommario):
An aeroacoustic study was conducted on a 26%-scale Boeing 777 main landing gear in the Virginia Tech (VT) Anechoic Stability Wind Tunnel. The VT Anechoic Stability Wind Tunnel allowed noise measurements to be carried out using both a 63-elements microphone phased array and a linear array of 15 microphones. The noise sources were identified from the flyover view under various flow speeds and the phased array positioned in both the near and far-field. The directivity pattern of the landing gear was determined using the linear array of microphones. The effectiveness of 4 passive noise control devices was evaluated. The 26%-scale model tested was a faithful reproduction of the full-scale landing gear and included most of the full-scale details with accuracy down to 3 mm. The same landing gear model was previously tested in the original hard-walled configuration of the VT tunnel with the same phased array mounted on the wall of the test section, i.e. near-field position. Thus, the new anechoic configuration of the VT wind tunnel offered a unique opportunity to directly compare, using the same gear model and phased array instrumentation, data collected in hard-walled and semi-anechoic test sections. The main objectives of the present work were (i) to evaluate the validity of conducting aeroacoustic studies in non-acoustically treated, hard-walled wind tunnels, (ii) to test the effectiveness of various streamlining devices (passive noise control) at different flyover locations, and (iii) to assess if phased array measurements can be used to estimate noise reduction. As expected, the results from this work show that a reduction of the background noise (e.g. anechoic configuration) leads to significantly cleaner beamforming maps and allows one to locate noise sources that would not be identified otherwise. By using the integrated spectra for the baseline landing gear, it was found that in the hard-walled test section the levels of the landing gear noise were overestimated. Phased array measurements in the near and far-field positions were also compared in the anechoic configuration. The results showed that straight under the gear, near-field measurements located only the lower-truck noise sources, i.e. noise components located behind the truck were shielded. It was thus demonstrated that near-field, phased-array measurements of the landing gear noise straight under the gear are not suitable. The array was also placed in the far-field, on the rear-arc of the landing gear. From this position, other noise sources such as the strut could be identified. This result demonstrated that noise from the landing gear on the flyover path cannot be characterized by only taking phased array measurement right under the gear. The noise reduction potential of various streamlining devices was estimated from phased array measurements (by integrating the beamforming maps) and using the linear array of individually calibrated microphones. Comparison of the two approaches showed that the reductions estimated from the phased array and a single microphone were in good agreement in the far-field. However, it was found that in the near-field, straight under the gear, phased array measurements greatly overestimate the attenuation.
Master of Science
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8

Van, Mierlo Koen. "Computational analysis of the flow field and noise radiation of a generic main landing gear configuration". Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/388076/.

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Abstract (sommario):
This study investigates the flow field and acoustics of a generic four wheel main landing gear. The landing gear is an important airframe noise source during the approach phase. The characteristics of the flow field around the bogie area of the main landing gear are largely unknown. CFD simulations using the DES turbulence model have been used to calculate the unsteady flow field around a generic landing gear model. The surface pressure data has been sampled and used in a FW-H solver to determine far field noise levels. Two different landing gear models have been used, a simplified geometry and a more realistic complex geometry. Three different bogie angles have been simulated: horizontal bogie aligned with the flow, 10⁰ toe up and 10⁰ toe down. Strong streamwise vortices are generated at the front wheels of the landing gear. The trajectory of these vortices determines where the turbulent flow interacts with the downstream components. This interaction leads to surface pressure fluctuations which are a major noise source. The flow field of the simplified configurations shows a consistent trend of the trajectory of the streamwise vortices with respect to changes in bogie angle. The far field noise levels generated by the different components of the simplified configurations are related to the distance at which the streamwise vortices pass. The additional components of the complex landing gear geometry change the characteristics of the flow field. The strong streamwise vortices persist but they do not show the same trend as for the simplified configurations. The wake of the articulation link generates a turbulent in flow for the other components. The different characteristics of the flow field of the complex configurations lead to significant changes in the far field noise levels of the components compared to the simplified configurations.
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9

Bouchouireb, Hamza. "Identification and modelling of noise sources on a realisticnose landing gear using phased array methods applied tocomputational data". Thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209186.

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Abstract (sommario):
Due to the recent development of quieter turbofan engines, airframe noise has started to emerge asthe most important noise source. This is particularly true during the approach/landing phase, whenthe engines are operated at low-thrust levels. In order to meet future noise level regulations, thecharacterization and subsequent reduction of landing gear induced noise is necessary. Wind-tunnelaeroacoustic tests have always been the favoured method for assessing and studying the noise generatedby landing gears, but their prohibitive cost has steered the attention towards numerical methods.Since direct flow noise simulations are still too demanding in computer resources, there is astrong interest in developing coupled CFD-CAA simulations as a tool to model and identify flownoise sources. More recently, they have been coupled with phased array methods in order to conductaeroacoustic studies on scaled-down, or simplified, aircraft components. This project investigates theaerodynamic sound sources on a realistic nose landing gear using numerical phased array methods,based on array data extracted from compressible Detached Eddy Simulations of the flow. Assumingmonopole and dipole modes of propagation, the sound sources are identified in the source regionthrough beamforming approaches: conventional beamforming, dual linear programming (dual-LP)deconvolution, orthogonal beamforming and CLEAN-SC. To assess the accuracy of the employedmethods, beamforming maps from flyover, sideline and forward point of views are obtained andcompared to experimental ones originating from wind-tunnel experiments performed on the samenose landing gear configuration by industrial and academic partners of the ALLEGRA project. Anarray design metric is defined to quantitatively assess the fitness of the employed arrays with respectto the different frequencies and distances separating the beamforming and array planes. A geneticalgorithm based on the Differential Evolution method is used to generate optimized arrays for selectedfrequencies in order to reduce the computational size of the problems solved. The modelledsources are used to generate far-field spectra which are subsequently compared to the ones obtainedwith the FfowcsWilliams and Hawkings acoustic analogy. The results show a good concordance betweenthe numerical phased array beamforming maps and the experimental ones, and a good matchbetween the far-field spectra up to a certain frequency threshold corresponding to the quality of themesh used. The presence of specific noise sources has been validated and their contribution to theoverall generated noise has been quantified. The results obtained demonstrate the potential of numericalphased array methods as a legitimate tool for aeroacoustic simulations in general and as atool to gain insight into the noise generation mechanisms of landing gear components in particular.
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10

Čavojský, Tomáš. "Návrh podvozku malého dvoumístného letounu". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442821.

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Abstract (sommario):
This diploma thesis deals with the landing gear design of the small two-seat aircraft. The introduction focuses on the conceptual gear design and shock absorber computational dynamic characteristic model. The practical part is focused on the landing gear construction according to the selected parameters based on the conceptual and computational model. The diploma thesis ends with strength calculations and production documentation.
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Più fonti

Libri sul tema "NOISE LANDING GEAR"

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L, Martin James, Hardy Gordon H e Ames Research Center, a cura di. Flight investigation of the use of a nose gear jump strut to reduce takeoff ground roll distance of STOL aircraft. Moffett Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 1994.

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National Aeronautics and Space Administration (NASA) Staff. Aeroacoustic Simulation of Nose Landing Gear on Adaptive Unstructured Grids with FUN3D. Independently Published, 2019.

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Flight investigation of the use of a nose gear jump strut to reduce takeoff ground roll distance of STOL aircraft. Moffett Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 1994.

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Capitoli di libri sul tema "NOISE LANDING GEAR"

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Wang, Jian, Wenjiang Wang e Kangle Xu. "Acoustical Wind Tunnel Studies of Landing Gear Noise". In Fluid-Structure-Sound Interactions and Control, 69–75. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-48868-3_11.

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Wang, L., C. Mockett, T. Knacke e F. Thiele. "Noise Prediction of a Rudimentary Landing Gear Using Detached-Eddy Simulation". In Progress in Hybrid RANS-LES Modelling, 279–89. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-31818-4_24.

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Langtry, R., e P. Spalart. "Detached Eddy Simulation of a Nose Landing-Gear Cavity". In IUTAM Symposium on Unsteady Separated Flows and their Control, 357–66. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-1-4020-9898-7_31.

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Guertsman, V. Y. "A Case Study of Nose Landing Gear Failure Caused by Fatigue". In ICAF 2011 Structural Integrity: Influence of Efficiency and Green Imperatives, 635–44. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-1664-3_51.

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Tian, Wei, e Qin Sun. "Applied Design Optimization of Nose Landing Gear Cabin Structure of Airplane". In Lecture Notes in Electrical Engineering, 557–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-54233-6_61.

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Alqash, Sultan, e Kamran Behdinan. "An Efficient Far-Field Noise Prediction Framework for the Next Generation of Aircraft Landing Gear Designs". In Advanced Multifunctional Lightweight Aerostructures: Design, Development, and Implementation, 151–85. ASME-Wiley, 2021. http://dx.doi.org/10.1115/1.862ama_ch8.

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Zhang, Jiaxian, Jiliang Tu, Hui Liu e Shixue Zhang. "Investigation on the Effect of Anti-Braking System on Nose Landing Gear Shimmy". In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde221072.

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The influence of anti-braking system on the shimmy region and oscillation characteristics of the nose landing gear is studied. The moment generated by the braking system is modeled as a function of the adhesion coefficient and the torsional oscillation speed, and it is incorporated into the landing gear oscillation non-linear dynamic model. The results of analysis show that the braking frequency is increased by 50%, the area of the lateral dominant shimmy region is increased by 6.9%, the area of the torsional dominant shimmy region is reduced by 18.8%, and the amplitude of the torsional oscillation is suppressed. The braking amplitude is increased by 22%, the area of lateral dominant shimmy region is decreased by 3.1%, and the area of torsional dominant shimmy region is increased by 15.5%.
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"Cracking in an Aircraft Nose Landing Gear Strut". In Handbook of Case Histories in Failure Analysis, 11–14. ASM International, 1993. http://dx.doi.org/10.31399/asm.fach.v02.c9001292.

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Nonato, Raphael Basilio Pires, e Alexander Dias Lopes. "STRUCTURAL OPTIMIZATION OF A NOSE LANDING GEAR FOR CESSNA 172 AIRPLANE". In Engenharia mecânica: A influência de máquinas, ferramentas e motores no cotidiano do homem 2, 34–48. Atena Editora, 2021. http://dx.doi.org/10.22533/at.ed.1732118063.

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Rahmani, M., e K. Behdinan. "On the analysis of passive vibration mitigation of nose landing gears". In Advances in Engineering Materials, Structures and Systems: Innovations, Mechanics and Applications, 43–48. CRC Press, 2019. http://dx.doi.org/10.1201/9780429426506-7.

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Atti di convegni sul tema "NOISE LANDING GEAR"

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Vuillot, Francois, Nicolas Lupoglazoff, David Luquent, Laurent Sanders, Eric Manoha e Stephane Redonnet. "Hybrid CAA solutions for nose landing gear noise". In 18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference). Reston, Virigina: American Institute of Aeronautics and Astronautics, 2012. http://dx.doi.org/10.2514/6.2012-2283.

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Stalnov, Oksana, David Angland e Xin Zhang. "On the Contribution of Individual Landing Gear Components to Landing Gear Loads and Noise". In 31st AIAA Applied Aerodynamics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2013. http://dx.doi.org/10.2514/6.2013-3153.

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Salt, Eric, Marko Arezina, James Lepore e Samir Ziada. "Experimental Investigation of Landing Light Orientation on Landing Gear Noise". In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45137.

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A simplified model of a landing gear is tested in a wind tunnel to investigate the effect of the landing light orientation on the resulting noise generation. Examination of the near-field pressure fluctuations, combined with phase-locked stereoscopic particle imaging velocimetry (SPIV) of the unsteady wake identified two distinct sources of pressure fluctuations. The higher frequency source has a wide frequency band and is situated in the outer regions of the wake near the lights. However, the lower frequency source is found to be stronger, has a narrower frequency band, and is developed further downstream in the wake, closer to the wake centerline. The lower frequency source is observed to be rather robust as it is hardly affected by the orientation of the landing lights, whereas the higher frequency source becomes weaker as the distance between the lights is reduced. The effect of a splitter plate positioned downstream of the strut is also investigated as a means of disrupting the lower frequency pressure fluctuations. Although the lower frequency source is considerably reduced by the splitter plate, substantial enhancement of the higher frequency source is observed.
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Merino-Martinez, Roberto, Lothar Bertsch, Dick G. Simons e Mirjam Snellen. "Analysis of landing gear noise during approach". In 22nd AIAA/CEAS Aeroacoustics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2016. http://dx.doi.org/10.2514/6.2016-2769.

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Kennedy, John, Eleonora Neri e Gareth J. Bennett. "The Reduction of Main Landing Gear Noise". In 22nd AIAA/CEAS Aeroacoustics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2016. http://dx.doi.org/10.2514/6.2016-2900.

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Wang, Liang, Charles Mockett, Thilo Knacke e Frank Thiele. "Detached-Eddy Simulation of Landing-Gear Noise". In 19th AIAA/CEAS Aeroacoustics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2013. http://dx.doi.org/10.2514/6.2013-2069.

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Dobrzynski, Werner, Leung Chow, Pierre Guion e Derek Shiells. "Research into Landing Gear Airframe Noise Reduction". In 8th AIAA/CEAS Aeroacoustics Conference & Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2002. http://dx.doi.org/10.2514/6.2002-2409.

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Boorsma, Koen, Xin Zhang e Nicolas Molin. "Perforated Fairings for Landing Gear Noise Control". In 14th AIAA/CEAS Aeroacoustics Conference (29th AIAA Aeroacoustics Conference). Reston, Virigina: American Institute of Aeronautics and Astronautics, 2008. http://dx.doi.org/10.2514/6.2008-2961.

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Thomas, Flint, Alexey Kozlov e Thomas Corke. "Plasma Actuators for Landing Gear Noise Reduction". In 11th AIAA/CEAS Aeroacoustics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2005. http://dx.doi.org/10.2514/6.2005-3010.

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Oerlemans, Stefan, Constantin Sandu, Nicolas Molin e Jean-Francois Piet. "Reduction of Landing Gear Noise Using Meshes". In 16th AIAA/CEAS Aeroacoustics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2010. http://dx.doi.org/10.2514/6.2010-3972.

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Rapporti di organizzazioni sul tema "NOISE LANDING GEAR"

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Sullivan, Joel A., e Susan J. Evans. Development of the C-17 Nose Landing Gear Container, CNU-691/E. Fort Belvoir, VA: Defense Technical Information Center, aprile 2007. http://dx.doi.org/10.21236/ada470353.

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