Showing papers on "Aircraft noise published in 2012"
TL;DR: People living in the vicinity of wind turbines are at risk of being annoyed by the noise, an adverse effect in itself, which could lead to sleep disturbance and psychological distress.
173 citations
TL;DR: In this article, a flat plate was mounted on a two-axis traverse in two distinct configurations: (1) as a shield between the jet and the observer (microphone array) and (2) as reflecting surface on the opposite side of the jet from the observer.
Abstract: Many configurations proposed for the next generation of aircraft rely on the wing or other aircraft surfaces to shield the engine noise from the observers on the ground. However, the ability to predict the shielding effect and any new noise sources that arise from the high-speed jet flow interacting with a hard surface is currently limited. Furthermore, quality experimental data from jets with surfaces nearby suitable for developing and validating noise prediction methods are usually tied to a particular vehicle concept and, therefore, very complicated. The Jet/Surface Interaction Test was intended to supply a high quality set of data covering a wide range of surface geometries and positions and jet flows to researchers developing aircraft noise prediction tools. During phase one, the goal was to measure the noise of a jet near a simple planar surface while varying the surface length and location in order to: (1) validate noise prediction schemes when the surface is acting only as a jet noise shield and when the jet/surface interaction is creating additional noise, and (2) determine regions of interest for more detailed tests in phase two. To meet these phase one objectives, a flat plate was mounted on a two-axis traverse in two distinct configurations: (1) as a shield between the jet and the observer (microphone array) and (2) as a reflecting surface on the opposite side of the jet from the observer. The surface was moved through axial positions 2 ≤ xTE/Dj ≤ 20 (measured at the surface trailing edge, xTE, and normalized by the jet diameter, Dj) and radial positions 1 ≤ h/Dj ≤ 20. Far-field and phased array noise data were acquired at each combination of axial and radial surface location using two nozzles and at 8 different jet exit conditions across several flow regimes (subsonic cold, subsonic hot, underexpanded, ideally expanded, and overexpanded supersonic cold). The far-field noise results, discussed here, show where the surface shields some of the jet noise and, depending on the location of the surface and the observer, where scrubbing and trailing edge noise sources are created as a surface extends downstream and approaches the jet plume.
101 citations
TL;DR: Type of housing, length of residence, location of rooms and the use of noise reducing remedies modified the relationship between noise and hypertension, however, the effects were not always in the direction of a stronger association in higher exposed subjects.
Abstract: In the cross-sectional hypertension and exposure to noise near airports study the relationship between road traffic noise, aircraft noise and hypertension and annoyance was investigated. The data collection comprised a variety of potentially exposure modifying factors, including type of housing, location of rooms, window opening habits, use of noise-reducing remedies, shielding due to obstacles, lengths of exposure. In the present paper the quantitative role of these factors on the relationship between road and aircraft noise exposure and outcomes was analyzed. Multiple logistic and linear regression models were calculated including these co-factors and related interaction terms with noise indicators, as well as stratified analyses. Type of housing, length of residence, location of rooms and the use of noise reducing remedies modified the relationship between noise and hypertension. However, the effects were not always in the direction of a stronger association in higher exposed subjects. Regarding annoyance, type of housing, location of rooms, noise barriers, window opening habits, noise insulation, the use of noise reducing remedies, hours spent at home during daytime were significant effect modifiers. The use of noise-reducing remedies turned out to be indicators of perceived noise disturbance rather than modifiers reducing the annoyance.
90 citations
TL;DR: Nocturnal freight train noise exposure in Germany was associated with increased awakening probabilities exceeding those for aircraft noise and contrasting the findings of many annoyance surveys and annoyance ratings of the study.
81 citations
TL;DR: Investigating the relationship between noise levels from railway traffic and general annoyance is influenced by number of trains, the presence of ground borne vibrations, and building situational factors, such as orientation of balcony/patio and bedroom window implies that, for the proportion annoyed to be equal, a 5 - 7 dB lower noise level is needed.
Abstract: Internationally accepted exposure-response relationships show that railway noise causes less annoyance than road traffic and aircraft noise. Railway transport, both passenger and freight transport, is increasing, and new railway lines are planned for environmental reasons. The combination of more frequent railway traffic and faster and heavier trains will, most probably, lead to more disturbances from railway traffic in the near future. To effectively plan for mitigations against noise and vibration from railway traffic, new studies are needed to obtain a better basis of knowledge. The main objectives of the present study was to investigate how the relationship between noise levels from railway traffic and general annoyance is influenced by (i) number of trains, (ii) the presence of ground borne vibrations, and (iii) building situational factors, such as orientation of balcony/patio and bedroom window. Socio-acoustic field studies were executed in residential areas; (1) with relatively intense railway traffic; (2) with strong vibrations, and; (3) with the most intense railway traffic in the country. Data was obtained for 1695 respondents exposed to sound levels ranging from L(Aeq,24h) 45 to 65 dB. Both number of trains and presence of ground-borne vibrations, and not just the noise level per se, are of relevance for how annoying railway noise is perceived. The results imply that, for the proportion annoyed to be equal, a 5 - 7 dB lower noise level is needed in areas where the railway traffic causes strong ground-borne vibrations and in areas with a very large number of trains. General noise annoyance was twice as high among residents in dwellings with balcony / patio oriented towards the railway and about 1.5 times higher among residents with bedroom windows facing the railway.
76 citations
TL;DR: A review of both assessment and action implementation procedures focusing on the dominant--in the area--aircraft traffic noise is presented, with emphasis to a full calculation of Strategic Noise Map (SNM) scenarios of actual and future airport operation using the ECAC.
68 citations
TL;DR: In this paper, the authors found that those schools located in the vicinity of Heathrow Airport are more likely to experience overheating and poor air quality due to aircraft noise, which can subsequently have a negative impact on students' achievements.
56 citations
Book•
17 Dec 2012
TL;DR: In this article, the authors present a model of a single-engine single-rotor aircraft with three types of components: engine, propeller, and throttle control system, and conductance of the aircraft.
Abstract: 1. Prolegomena 2. Aircraft models 3. Weight and balance performance 4. Aerodynamic performance 5. Engine performance 6. Propeller performance 7. Aeroplane trim 8. Flight envelopes 9. Take-off and field performance 10. Climb performance 11. Descent and landing performance 12. Cruise performance 13. Manoeuvre performance 14. Thermo-structural performance 15. Mission analysis 16. Aircraft noise: noise sources 17. Aircraft noise: propagation 18. Aircraft noise: flight trajectories 19. Environmental performance 20. Epilogue.
53 citations
04 Jun 2012
TL;DR: In this paper, a numerical procedure for the prediction of aircraft noise certi cation metrics starting from the aircraft trajectory is described, which is applied to the nose landing gear of a Gulfstream business jet.
Abstract: This paper describes a numerical procedure for the prediction of aircraft noise certi cation metrics starting from the aircraft trajectory. The procedure is applied to the nose landing gear of a Gulfstream business jet. The numerical core of the procedure is a hybrid aeroacoustic method based on a lattice Boltzmann ow simulation and a Ffowcs-Williams & Hawkings noise propagation computation. The hybrid method is initially validated by computing the noise generated by a geometrically simpli ed model of the same landing gear installed on a at plate and comparing wall pressure and fareld noise spectra with wind-tunnel measurements. The same numerical method and a similar discretized model are then employed to compute the unsteady ow eld past the real landing gear deployed under the aircraft. The upstream ow conditions are the same occurring during a ight along a
ominally" constant descent trajectory at the nearest point to the ground microphone. Comparisons between the predicted noise levels and the measured ones during a ight test, with only the nose landing gear deployed and other airframe and engine sources kept at their admissible minimum, are in good agreement.
49 citations
TL;DR: Standards and recommended practices, designed for “Balanced approach” to aircraft noise management around airports, are presented and an overview of measures applied by airports worldwide in order to reduce noise in the surroundings is provided showing their frequency and variety.
49 citations
TL;DR: The model fits all of the road traffic findings well, but the prevalence of annoyance due to rail noise is more accurately predicted separately for interviewing sites with and without high levels of vibration and/or rattle.
Abstract: Fidell et al. [(2011), J. Acoust. Soc. Am. 130(2), 791-806] have shown (1) that the rate of growth of annoyance with noise exposure reported in attitudinal surveys of the annoyance of aircraft noise closely resembles the exponential rate of change of loudness with sound level, and (2) that the proportion of a community highly annoyed and the variability in annoyance prevalence rates in communities are well accounted for by a simple model with a single free parameter: a community tolerance level (abbreviated CTL, and represented symbolically in mathematical expressions as Lct), expressed in units of DNL. The current study applies the same modeling approach to predicting the prevalence of annoyance of road traffic and rail noise. The prevalence of noise-induced annoyance of all forms of transportation noise is well accounted for by a simple, loudness-like exponential function with community-specific offsets. The model fits all of the road traffic findings well, but the prevalence of annoyance due to rail no...
01 Jul 2012
TL;DR: In this paper, the authors provide an assessment of the current state of the art for aircraft noise prediction by carefully analyzing the results from prediction tools and from the experimental databases to determine errors and uncertainties and compare results to validate the predictions.
Abstract: A goal of NASA s Fundamental Aeronautics Program is the improvement of aircraft noise prediction. This document provides an assessment, conducted from 2006 to 2009, on the current state of the art for aircraft noise prediction by carefully analyzing the results from prediction tools and from the experimental databases to determine errors and uncertainties and compare results to validate the predictions. The error analysis is included for both the predictions and the experimental data and helps identify where improvements are required. This study is restricted to prediction methods and databases developed or sponsored by NASA, although in many cases they represent the current state of the art for industry. The present document begins with an introduction giving a general background for and a discussion on the process of this assessment followed by eight chapters covering topics at both the system and the component levels. The topic areas, each with multiple contributors, are aircraft system noise, engine system noise, airframe noise, fan noise, liner physics, duct acoustics, jet noise, and propulsion airframe aeroacoustics.
TL;DR: Two laboratory studies showed significant dose-response relationships between sound pressure level and subjective comfort ratings which differed due to the noise at specific seat positions in the aircraft, suggesting acoustic cabin design should consider measures beyond noise level reduction altering noise characteristics to improve passengers' comfort and well-being.
Abstract: The effects of cabin noise on subjective comfort assessments were systematically investigated in order to reveal optimisation potentials for an improved passenger noise acceptance. Two aircraft simulation studies were conducted. An acoustic laboratory test facility provided with loudspeaker systems for realistic sound presentations and an aircraft cabin simulator (Dornier Do 728) with a high degree of ecological validity were used. Subjects were exposed to nine different noise patterns (three noise levels ranging from 66 to 78 dB(A) combined with three different frequency spectra). Regression analysis demonstrated a significant increase of passengers' acceptance with lower noise levels and significant effects of different frequency spectra determined by seat position in the aircraft cabin (front, middle, rear). Acoustic cabin design should therefore consider measures beyond noise level reduction altering noise characteristics to improve passengers' comfort and well-being in the aircraft cabin. Practitione...
TL;DR: The aircraft noise problem is reviewed and a description and assessment of a number of sound propagation methods suitable for applications with a background mean flow field pertinent to aircraft noise are described and assessed.
Abstract: Noise generated by civil transport aircraft during take-off and approach-to-land phases of operation is an environmental problem. The aircraft noise problem is firstly reviewed in this article. The review is followed by a description and assessment of a number of sound propagation methods suitable for applications with a background mean flow field pertinent to aircraft noise. Of the three main areas of the noise problem, i.e. generation, propagation, and radiation, propagation provides a vital link between near-field noise generation and far-field radiation. Its accurate assessment ensures the overall validity of a prediction model. Of the various classes of propagation equations, linearised Euler equations are often casted in either time domain or frequency domain. The equations are often solved numerically by computational aeroacoustics techniques, bur are subject to the onset of Kelvin-Helmholtz (K-H) instability modes which may ruin the solutions. Other forms of linearised equations, e.g. acoustic perturbation equations have been proposed, with differing degrees of success.
TL;DR: The three-segment approach procedure has been obtained as an optimized flight path which can substantially reduce noise levels and could benefit both airlines and communities.
TL;DR: In this article, the authors discuss various issues in the implementation of a local market for aircraft noise licenses to solve the noise externalities harming the residents located near airports and discuss the design of such markets is affected by aircraft heterogeneity, wind contingencies, peak times, runways capacity constraints, hub strategies, and airport planning.
Abstract: This paper discusses various issues in the implementation of a local market for aircraft noise licenses to solve the noise externalities harming the residents located near airports. The design of such markets is affected by aircraft heterogeneity, wind contingencies, peak times, runways capacity constraints, hub strategies, and airport planning is discussed.
01 Jan 2012
TL;DR: An introduction is given of phased array beamforming techniques for locating acoustic sources, and it is explained how this technique can be applied to wind tunnel measurements.
Abstract: Description of work An introduction is given of phased array beamforming techniques for locating acoustic sources. Starting from basic principles, the Conventional Beamforming technique is described. It is explained how this technique can be applied to wind tunnel measurements. Further, a number of advanced array processing techniques are discussed. One chapter is devoted to the array processing technique for the location of moving sources. This technique can be applied to rotating sources, for example on wind turbine blades, and to source location on aircraft flying over a microphone array.
TL;DR: In this article, the results from the modelling based on a one-dimensional sawtooth waveform capture the essential features of the rotor-alone pressure field as it propagates upstream inside a hard-walled inlet duct.
TL;DR: Cognitive learning was changed structurally in the aircraft noise group and was accompanied by higher sympathetic activity and difficulties in changing cognitive strategies during noise are discussed as underlying mechanisms.
04 Jun 2012
TL;DR: In this article, a ray-tracing algorithm is used to define multiple curved propagation paths, if the atmosphere allows, between the moving source and listener, and a final step assigns each resulting signal to its corresponding receiver angle for the simulation of a flyover in a virtual reality environment.
Abstract: This paper describes a new framework for the simulation of aircraft flyover noise through a non-standard atmosphere. Central to the framework is a ray-tracing algorithm which defines multiple curved propagation paths, if the atmosphere allows, between the moving source and listener. Because each path has a different emission angle, synthesis of the sound at the source must be performed independently for each path. The time delay, spreading loss and absorption (ground and atmosphere) are integrated along each path, and applied to each synthesized aircraft noise source to simulate a flyover. A final step assigns each resulting signal to its corresponding receiver angle for the simulation of a flyover in a virtual reality environment. Spectrograms of the results from a straight path and a curved path modeling assumption are shown. When the aircraft is at close range, the straight path results are valid. Differences appear especially when the source is relatively far away at shallow elevation angles. These differences, however, are not significant in common sound metrics. While the framework used in this work performs off-line processing, it is conducive to real-time implementation.
04 Jun 2012
TL;DR: In this article, an 18-scale, semi-span Gulfstream aircraft model is used to perform detailed studies of airframe noise associated with main landing gear, flap components, and gear-flap interaction noise, as well as to evaluate novel noise reduction concepts.
Abstract: In this paper, we present unsteady surface pressure measurements for an 18%-scale, semi-span Gulfstream aircraft model. This high-fidelity model is being used to perform detailed studies of airframe noise associated with main landing gear, flap components, and gear–flap interaction noise, as well as to evaluate novel noise reduction concepts. The aerodynamic segment of the tests, conducted in the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel, was completed in November 2010. To discern the characteristics of the surface pressure fluctuations in the vicinity of the prominent noise sources, unsteady sensors were installed on the inboard and outboard flap edges, and on the main gear wheels, struts, and door. Various configurations were tested, including flap deflections of 0o, 20o, and 39o, with and without the main landing gear. The majority of unsteady surface pressure measurements were acquired for the nominal landing configuration where the main gear was deployed and the flap was deflected 39o. To assess the Mach number variation of the surface pressure amplitudes, measurements were obtained at Mach numbers of 0.16, 0.20, and 0.24. Comparison of the unsteady surface pressures with the main gear on and off shows significant interaction between the gear wake and the inboard flap edge, resulting in higher amplitude fluctuations when the gear is present.
01 Jan 2012
TL;DR: In this article, the authors explored the potential impact of noise from wind turbines on the global benefits of renewable energy production and the direct and tangible disbenefits felt by host communities.
Abstract: Research on wind power from around the world has demonstrated the importance of a disjuncture between the global benefits of renewable energy production and the direct and tangible disbenefits felt by host communities. One such potential impact is explored here — noise from wind turbines. It is commonly assumed that noise can be simply and accurately ‘measured’, and that account can be taken of the level of disturbance. However, noise measurement and annoyance are much more complicated issues. Whilst developers state that noise levels are within industry standards, and that it is possible to have a conversation standing underneath a turbine, this fails to: (1) appreciate that the industry guidelines are problematic and controversial in themselves; and (2) understand that noise is something that is ‘experienced’ rather than just ‘heard’.
TL;DR: A parametric study of open rotor noise in terms of its dependence on both front and rear blade numbers and blade tip speeds is undertaken.
Abstract: Open Rotor Noise consists of a number of different noise sources, each of which generates noise over a wide frequency range (one of the main features of contra-rotating turbomachinery). Consequently, parametric studies of relevance to engine and aircraft projects are best conducted over the audible frequency range and appraised in terms of the standard aircraft noise metric of EPNL. In this paper, we undertake a parametric study of open rotor noise in terms of its dependence on both front and rear blade numbers and blade tip speeds. In the first phase of the study blade numbers and tip speeds are varied independently. In the second phase they are varied simultaneously to show the close coupling between the two. The study is based on predictions and, to aid these predictions, extremely fast analytic tools - with some essential simplifications - are used for both the aerodynamics and noise calculations.
TL;DR: In this paper, the authors considered the environmental effects of airtraffic management speed constraints during the departure phase of flight and presented a CO2 versus noise trade-off study that compared aircraft departure procedures subject to speed constraints with a free speed scenario.
Abstract: This paper considers the environmental effects of airtraffic management speed constraints during the departure phase of flight. We present a CO2 versus noise trade-off study that compares aircraft departure procedures subject to speed constraints with a free speed scenario. A departure route at Gothenburg Landvetter Airport in Sweden is used as a case study and the analysis is based on airline flight recorded data extracted from the Airbus A321 aircraft. Results suggest that CO2 emissions could be reduced by 180 kg per flight if all departure speed constraints were removed at a cost of increased noise exposure below 70 dB(A).
04 Jun 2012
TL;DR: In this article, the authors describe efforts to improve the realism of synthesized source noise by including short term fluctuations, specifically for inlet-radiated tones resulting from the fan stage of turbomachinery.
Abstract: Fixed and rotary wing aircraft operations can have a significant impact on communities in proximity to airports. Simulation of predicted aircraft flyover noise, paired with listening tests, is useful to noise reduction efforts since it allows direct annoyance evaluation of aircraft or operations currently in the design phase. This paper describes efforts to improve the realism of synthesized source noise by including short term fluctuations, specifically for inlet-radiated tones resulting from the fan stage of turbomachinery. It details analysis performed on an existing set of recorded turbofan data to isolate inlet-radiated tonal fan noise, then extract and model short term tonal fluctuations using the analytic signal. Methodologies for synthesizing time-variant tonal and broadband turbofan noise sources using measured fluctuations are also described. Finally, subjective listening test results are discussed which indicate that time-variant synthesized source noise is perceived to be very similar to recordings.
04 Jun 2012
TL;DR: The Virtual Air Traffic System Simulation (VATSS) interdisciplinary project of RWTH Aachen University has the aim of presenting the effect of complete aircraft movements via visualization and auralization of aircraft noise in 3D Virtual Reality environments for the subjective assessment of aircraft noises.
Abstract: The issue of aircraft noise experienced by residents in the airport’s neighborhoods is one of subjective annoyance and a presentation of noise intensity in decibels alone might not be sufficient to give a clear understanding of noise abatement measures being carried out or the effect for instance of constructing a new runway at an airport. Although noise contours can be a great way of a quick assessment of noise impact over larger areas, noise quantified in numbers can prove lacking in capturing the actual annoyance caused by the noise to the residents. For this reason, a method providing a more subjective assessment of aircraft noise impact is required and auralization of complete aircraft movements could be one such way of better capturing the annoyance due to noise caused by aircraft. The Virtual Air Traffic System Simulation (VATSS) interdisciplinary project of RWTH Aachen University has the aim of presenting the effect of complete aircraft movements via visualization and auralization of aircraft noise in 3-D Virtual Reality environments for the subjective assessment of aircraft noise. This paper focusses on the interdisciplinary collaboration of the Institute of Aerospace Systems and the Institute of Technical Acoustics of RWTH Aachen to produce a capability of auralizing complete time-dependent take-off and landing procedures up to an altitude of 3000 meters. The noise produced by a conventional aircraft with a turbofan engine is modeled and the ILR’s capability to model aircraft noise for complete 4-D take-off and landing procedures is shown along with the technique to auralize complete standard procedures as well as noise abatement procedures with time-varying settings. Both broadband and tonal noise components for dominant sources are auralized for the movements.
04 Jun 2012
TL;DR: The recently conducted refurbishment of the low speed wind tunnel NWB, operated by the foundation Deutsch-Niederlandische Windkanale (DNW), meets future research challenges in aircraft noise reduction.
Abstract: *Up to now significant progress in aeroacoustic rese arch was limited because no acoustic wind tunnel of relevant kind, size and quality was available in Europe. The recently conducted refurbishment of the low speed wind tunnel NWB, operated by the foundation Deutsch-Niederlandische Windkanale (DNW), meets future research challenges in aircraft noise reduction. Further progress in aviation noise research including noise prediction and noise reduction technologies but also the possibili ty to transfer research results into application depends on the availability of a suitab le aeroacoustic wind tunnel test facility which up to now was not available in Europe. This s ituation was critical in view of the aggressive noise reduction objectives for aviation noise defined by the EU for the year 2020. In recent years noise reduction at transport aircra ft has become an ever more demanding task since not the engines alone contribute to the overall noise of an aircraft but as well the turbulent flow past the airframe. Many of these complex aeroacoustic sources are not even understood properly. The refurbishment of the NWB wind tunnel in Braunschweig, Germany, addresses these issues and new requirements in the aeronautics research. The
TL;DR: To investigate the relationship curves between aircraft noise and the percentage of "highly annoyed" persons in China and also to get annoyance threshold of aircraft noise in China, a survey of community annoyance induced by aircraft noise exposure was carried out around Hangzhou Xiaoshan International Airport.
Abstract: A survey of community annoyance induced by aircraft noise exposure was carried out around Hangzhou Xiaoshan International Airport. To investigate the relationship curves between aircraft noise and the percentage of "highly annoyed" persons in China and also to get annoyance threshold of aircraft noise in China. Noise annoyance induced by aircraft noise exposure was assessed by 764 local residents around the airport using the International Commission on Biological Effect of Noise (ICBEN) scale. The status quo of aircraft noise pollution was measured by setting up 39 monitoring points. The interpolation was used to estimate the weighted effective continuous perceived noise levels (LWECPN) in different areas around the airport, and the graph of equal noise level contour was drawn. The membership function was used to calculate the annoyance threshold of aircraft noise. Data were analyzed using SPSS 16.0 and Origin 8.0. The results showed that if LWECPN was 64.3 dB (Ldn was 51.4 dB), then 15% respondents were highly annoyed. If LWECPN was 68.1 dB (Ldn was 55.0 dB), then 25% respondents were highly annoyed. The annoyance threshold of aircraft noise (LWECPN) was 73.7 dB, while the annoyance threshold of a single flight incident instantaneous noise level (LAmax) was 72.9 dB. People around the airport had felt annoyed before the aircraft noise LWECPN reached the standard limit.
TL;DR: In this article, the major components of jet noise in turbofan engines and a review of the jet noise reduction technologies are discussed and discussed in a multidisciplinary optimisation framework.
Abstract: Turbofan engines are commonly used for commercial transport due to their advantages of higher performance and lower noise. Jet noise is one of the principal noise sources of turbofan aeroplane engines and remains an acute environmental problem that requires advanced solutions. The ever-increasing demand for quieter engines requires the exploration of alternative techniques that could be used by themselves or in conjunction with existing methods. Significant progress continues to be made with noise reduction for turbofan engines. Analytical and semiempirical models have been developed to investigate the influence of some design tools when they are employed in a multidisciplinary optimisation framework. This paper discusses the major components of jet noise in turbofan engines and presents a review of jet noise reduction technologies.