Showing papers on "Aircraft noise published in 2013"

Aircraft class identification based on take-off noise signal segmentation in time

Abstract: Aircraft noise is one of the most uncomfortable kinds of sounds. That is why many organizations have addressed this problem through noise contours around airports, for which they use the aircraft type as the key element. This paper presents a new computational model to identify the aircraft class with a better performance, because it introduces the take-off noise signal segmentation in time. A method for signal segmentation into four segments was created. The aircraft noise patterns are extracted using an LPC (Linear Predictive Coding) based technique and the classification is made combining the output of four parallel MLP (Multilayer Perceptron) neural networks, one for each segment. The individual accuracy of each network was improved using a wrapper feature selection method, increasing the model effectiveness with a lower computational cost. The aircraft are grouped into classes depending on the installed engine type. The model works with 13 aircraft categories with an identification level above 85% in real environments.

Aircraft noise, health, and residential sorting: evidence from two quasi-experiments.

Abstract: SUMMARY We explore two unexpected changes in flight regulations to estimate the causal effect of aircraft noise on health. Detailed measures of noise are linked with longitudinal data on individual health outcomes based on the exact address information. Controlling for individual heterogeneity and spatial sorting into different neighborhoods, we find that aircraft noise significantly increases sleeping problems and headaches. Models that do not control for such heterogeneity and sorting substantially underestimate the negative health effects, which suggests that individuals self-select into residence based on their unobserved sensitivity to noise. Our study demonstrates that the combination of quasi-experimental variation and panel data is very powerful for identifying causal effects in epidemiological field studies. Copyright © 2013 John Wiley & Sons, Ltd.

NASA Glenn's Contributions to Aircraft Engine Noise Research

Abstract: This report reviews all engine noise research conducted at the NASA Glenn Research Center over the past 70 years. This report includes a historical perspective of the Center and the facilities used to conduct the research. Major noise research programs are highlighted to show their impact on industry and on the development of aircraft noise reduction technology. Noise reduction trends are discussed, and future aircraft concepts are presented. Since the 1960s, research results show that the average perceived noise level has been reduced by about 20 decibels (dB). Studies also show that, depending on the size of the airport, the aircraft fleet mix, and the actual growth in air travel, another 15 to 17 dB reduction will be required to achieve NASA's long-term goal of providing technologies to limit objectionable noise to the boundaries of an average airport.

Development of a SMA-Based, Slat-Cove Filler for Reduction of Aeroacoustic Noise Associated With Transport-Class Aircraft Wings

Abstract: Airframe noise is a significant part of the overall noise produced by typical, transport-class aircraft during the approach and landing phases of flight. Leading-edge slat noise is a prominent source of airframe noise. The concept of a slat-cove filler was proposed in previous work as an effective means of mitigating slat noise. Bench-top models were deployed at 75% scale to study the feasibility of producing a functioning slat-cove filler. Initial results from several concepts led to a more-focused effort investigating a deformable structure based upon pseudoelastic SMA materials. The structure stows in the cavity between the slat and main wing during cruise and deploys simultaneously with the slat to guide the aerodynamic flow suitably for low noise. A qualitative parametric study of SMA-enabled, slat-cove filler designs was performed on the bench-top. Computational models were developed and analyses were performed to assess the displacement response under representative aerodynamic load. The bench-top and computational results provide significant insight into design trades and an optimal design.

Airframe Noise Sub-Component Definition and Model

Abstract: Both in-house, and jointly with NASA under the Advanced Subsonic Transport (AST) program, Boeing Commerical Aircraft Company (BCA) had begun work on systematically identifying specific components of noise responsible for total airframe noise generation and applying the knowledge gained towards the creation of a model for airframe noise prediction. This report documents the continuation of the collection of database from model-scale and full-scale airframe noise measurements to compliment the earlier existing databases, the development of the subcomponent models and the generation of a new empirical prediction code. The airframe subcomponent data includes measurements from aircraft ranging in size from a Boeing 737 to aircraft larger than a Boeing 747 aircraft. These results provide the continuity to evaluate the technology developed under the AST program consistent with the guidelines set forth in NASA CR-198298.

Measuring subjective response to aircraft noise: the effects of survey context.

Abstract: In applied research, noise annoyance is often used as indicator of subjective reaction to aircraft noise in residential areas. The present study aims to show that the meaning which respondents attach to the concept of aircraft noise annoyance is partly a function of survey context. To this purpose a survey is conducted among residents living near Schiphol Airport, the largest airport in the Netherlands. In line with the formulated hypotheses it is shown that different sets of preceding questionnaire items influence the response distribution of aircraft noise annoyance as well as the correlational patterns between aircraft noise annoyance and other relevant scales.

Measurement of aircraft noise in a high background noise environment using a microphone array

Abstract: This paper examines sound level meter errors when measuring direct fly-over aircraft noise in presence of background noise. Since the meter is unable to separate aircraft noise from background noise, an array of 12 microphones is used to measure direct aircraft noise avoiding the effect of the ground reflections and urban background noise. Using this technique, aircraft noise can be separated from the background noise providing a reference value of the aircraft sound pressure level for the sound level meter measurement. Measurement is carried out using both a sound level meter and the array in an urban environment with high background noise level near Barcelona Airport. Finally, the experimental measurement errors of the sound meter are within 1 dB of the theoretical values.

Airframe Noise Studies: Review and Future Direction

Abstract: This report contains the following information: 1) a review of airframe noise research performed under NASA's Advanced Subsonic Transport (AST) program up to the year 2000, 2) a comparison of the year 1992 airframe noise predictions with those using a year 2000 baseline, 3) an assessment of various airframe noise reduction concepts as applied to the year 2000 baseline predictions, and 4) prioritized recommendations for future airframe noise reduction work. NASA's Aircraft Noise Prediction Program was the software used for all noise predictions and assessments. For future work, the recommendations for the immediate future focus on the development of design tools sensitive to airframe noise treatment effects and on improving the basic understanding of noise generation by the landing gear as well as on its reduction.

Noise prediction toolbox used by the DLR aircraft noise working group

Abstract: Focus of the activities of the aircraft noise working group of the German Aerospace Center (DLR) is the development and application of aircraft noise calculation models. The different tools currently in use are covering the range from best practice models like FAA´s INM or the German AzB up to the sophisticated partial-sound-source models SIMUL and PANAM, which were developed at DLR during the last years. Consequently, the field of application is very large – reaching from the classical aircraft noise prediction tasks for land-use planning up to a noise optimization already during conceptual vehicle design. This paper gives an overview on these tools, typical applications as well as their advantages and limitations. Special attention will be paid on the SIMUL and PANAM models, which are currently used mainly for scientific applications.

The Effects of Surfaces on the Aerodynamics and Acoustics of Jet Flows

Abstract: Aircraft noise mitigation is an ongoing challenge for the aeronautics research community. In response to this challenge, low-noise aircraft concepts have been developed that exhibit situations where the jet exhaust interacts with an airframe surface. Jet flows interacting with nearby surfaces manifest a complex behavior in which acoustic and aerodynamic characteristics are altered. In this paper, the variation of the aerodynamics, acoustic source, and far-field acoustic intensity are examined as a large at plate is positioned relative to the nozzle exit. Steady Reynolds-Averaged Navier-Stokes solutions are examined to study the aerodynamic changes in the field-variables and turbulence statistics. The mixing noise model of Tam and Auriault is used to predict the noise produced by the jet. To validate both the aerodynamic and the noise prediction models, results are compared with Particle Image Velocimetry (PIV) and free-field acoustic data respectively. The variation of the aerodynamic quantities and noise source are examined by comparing predictions from various jet and at plate configurations with an isolated jet. To quantify the propulsion airframe aeroacoustic installation effects on the aerodynamic noise source, a non-dimensional number is formed that contains the flow-conditions and airframe installation parameters.

Full-Scale Turbofan-Engine Turbine-Transfer Function Determination Using Three Internal Sensors

Abstract: Existing NASA/Honeywell EVNERT full-scale static engine test data is analyzed by using source-separation techniques in order to determine the turbine transfer of the currently sub-dominant combustor noise. The results are used to assess the combustor-noise prediction capability of the Aircraft Noise Prediction Program (ANOPP). Time-series data from three sensors internal to the Honeywell TECH977 research engine is used in the analysis. The true combustor-noise turbine-transfer function is educed by utilizing a new three-signal approach. The resulting narrowband gain factors are compared with the corresponding constant values obtained from two empirical acoustic-turbine-loss formulas. It is found that a simplified Pratt & Whitney formula agrees better with the experimental results for frequencies of practical importance. The 130 deg downstream-direction far-field 1/3-octave sound-pressure levels (SPL) results of Hultgren & Miles are reexamined using a post-correction of their ANOPP predictions for both the total noise signature and the combustion-noise component. It is found that replacing the standard ANOPP turbine-attenuation function for combustion noise with the simplified Pratt & Whitney formula clearly improves the predictions. It is recommended that the GECOR combustion-noise module in ANOPP be updated to allow for a user-selectable switch between the current transmission-loss model and the simplified Pratt & Whitney formula. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The Subsonic Fixed Wing Project's Reduce-Perceived-Noise Technical Challenge aims to develop concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries. The reduction of aircraft noise is critical to enabling the anticipated large increase in future air traffic.

A Comparison of Combustor-Noise Models

Abstract: The present status of combustor-noise prediction in the NASA Aircraft Noise Prediction Program (ANOPP)1 for current-generation (N) turbofan engines is summarized. Several semi-empirical models for turbofan combustor noise are discussed, including best methods for near-term updates to ANOPP. An alternate turbine-transmission factor2 will appear as a user selectable option in the combustor-noise module GECOR in the next release. The three-spectrum model proposed by Stone et al.3 for GE turbofan-engine combustor noise is discussed and compared with ANOPP predictions for several relevant cases. Based on the results presented herein and in their report,3 it is recommended that the application of this fully empirical combustor-noise prediction method be limited to situations involving only General-Electric turbofan engines. Long-term needs and challenges for the N+1 through N+3 time frame are discussed. Because the impact of other propulsion-noise sources continues to be reduced due to turbofan design trends, advances in noise-mitigation techniques, and expected aircraft configuration changes, the relative importance of core noise is expected to greatly increase in the future. The noise-source structure in the combustor, including the indirect one, and the effects of the propagation path through the engine and exhaust nozzle need to be better understood. In particular, the acoustic consequences of the expected trends toward smaller, highly efficient gas-generator cores and low-emission fuel-flexible combustors need to be fully investigated since future designs are quite likely to fall outside of the parameter space of existing (semi-empirical) prediction tools.

Modelling and Managing Airport Performance

Abstract: This book is divided into three sections: (1) Modelling Airport Performance; (2) Assessing Airport Impacts; and (3) Managing Airport Performance and Congestion The book provides very important information for researchers and practitioners in the global air transportation community The book also provides an integrated view of state-of-the-art research on measuring and improving the performance of airport systems with consideration of both airside and landside operations Areas of interest include capacity, delays, economic costs, noise, emissions and safety Portions of the book examine policies for managing congestion and allocating sparse capacity, as well as for mitigating the externalities of noise, emissions, and safety/risk

Comparing aircraft noise pollution and cost-risk effects of inland and offshore airports: The case of Dalian International Airport, Dalian, China

Abstract: China’s Dalian International Airport is taken to compare the aircraft noise pollution and the cost-risk effects of the expanded an existing inland and a proposed offshore airport. The findings show that the aircraft noise pollution of the offshore airport is much less than that of the expanded inland airport; the land-use cost, noise reduction charges and other risks of the offshore airport are also much less; the creation of the offshore airport may be more favorable to the city’s development.

Exposure to Road Traffic Noise and Children’s Behavioural Problems and Sleep Disturbance: Results from the GINIplus and LISAplus Studies

Abstract: Background: Exposure to transportation noise showed negative health effects in children and adults. Studies in children mainly focussed on aircraft noise at school. Aims: We aimed to investigate ro...

Aircraft noise technology review and medium and long term noise reduction goals

Abstract: This presentation will summarize the recommendations of the second ICAO Committee on Aviation Environmental Protection noise technology independent expert panel. The technologies being developed for reducing aircraft community noise in the mid term (10 years) and the long term (20 years) were reviewed. The review consisted of detailed presentations on aircraft noise reduction by various industry and government representatives on component noise reduction programs, highlighting novel noise reduction concepts being pursued and the progress that has been demonstrated or projected so far.

Analysis-Driven Design Optimization of a SMA-Based Slat-Cove Filler for Aeroacoustic Noise Reduction

Abstract: Airframe noise is a significant component of environmental noise in the vicinity of airports. The noise associated with the leading-edge slat of typical transport aircraft is a prominent source of airframe noise. Previous work suggests that a slat-cove filler (SCF) may be an effective noise treatment. Hence, development and optimization of a practical slat-cove-filler structure is a priority. The objectives of this work are to optimize the design of a functioning SCF which incorporates superelastic shape memory alloy (SMA) materials as flexures that permit the deformations involved in the configuration change. The goal of the optimization is to minimize the actuation force needed to retract the slat-SCF assembly while satisfying constraints on the maximum SMA stress and on the SCF deflection under static aerodynamic pressure loads, while also satisfying the condition that the SCF self-deploy during slat extension. A finite element analysis model based on a physical bench-top model is created in Abaqus such that automated iterative analysis of the design could be performed. In order to achieve an optimized design, several design variables associated with the current SCF configuration are considered, such as the thicknesses of SMA flexures and the dimensions of various components, SMA and conventional. Designs of experiment (DOE) are performed to investigate structural response to an aerodynamic pressure load and to slat retraction and deployment. DOE results are then used to inform the optimization process, which determines a design minimizing actuator forces while satisfying the required constraints.

Acoustic Performance of a Real-Time Three-Dimensional Sound-Reproduction System

Abstract: The Exterior Effects Room (EER) is a 39-seat auditorium at the NASA Langley Research Center and was built to support psychoacoustic studies of aircraft community noise. The EER has a real-time simulation environment which includes a three-dimensional sound-reproduction system. This system requires real-time application of equalization filters to compensate for spectral coloration of the sound reproduction due to installation and room effects. This paper describes the efforts taken to develop the equalization filters for use in the real-time sound-reproduction system and the subsequent analysis of the system s acoustic performance. The acoustic performance of the compensated and uncompensated sound-reproduction system is assessed for its crossover performance, its performance under stationary and dynamic conditions, the maximum spatialized sound pressure level it can produce from a single virtual source, and for the spatial uniformity of a generated sound field. Additionally, application examples are given to illustrate the compensated sound-reproduction system performance using recorded aircraft flyovers

Hybrid Wing Body Aircraft Acoustic Test Preparations and Facility Upgrades

Abstract: NASA is investigating the potential of acoustic shielding as a means to reduce the noise footprint at airport communities. A subsonic transport aircraft and Langley's 14- by 22-foot Subsonic Wind Tunnel were chosen to test the proposed "low noise" technology. The present experiment studies the basic components of propulsion-airframe shielding in a representative flow regime. To this end, a 5.8-percent scale hybrid wing body model was built with dual state-of-the-art engine noise simulators. The results will provide benchmark shielding data and key hybrid wing body aircraft noise data. The test matrix for the experiment contains both aerodynamic and acoustic test configurations, broadband turbomachinery and hot jet engine noise simulators, and various airframe configurations which include landing gear, cruise and drooped wing leading edges, trailing edge elevons and vertical tail options. To aid in this study, two major facility upgrades have occurred. First, a propane delivery system has been installed to provide the acoustic characteristics with realistic temperature conditions for a hot gas engine; and second, a traversing microphone array and side towers have been added to gain full spectral and directivity noise characteristics.

The effect of interior aircraft noise on pilot performance.

Abstract: This study examined the effect of the interior sounds of an aircraft cockpit on ratings of affect and expected performance decrement. While exposed to 12 interior aircraft sounds, of which half were modified to correspond to what is experienced with an active noise reduction (ANR) headset, 23 participants rated their affective reactions and how they believed their performance on various tasks would be affected. The results suggest that implementation of ANR-technique has a positive effect on ratings of expected performance. In addition, affective reactions to the noise are related to ratings of expected performance. The implications of these findings for both research and pilot performance are discussed.

Using supplemental aircraft noise information to assist airport neighbours understand aircraft noise

Abstract: This paper deals with the value of supplemental aircraft noise information in the form of combining aircraft movement numbers and noise levels to assist airport neighbours in understanding airport noise. To analyse the socio-spatial interaction of annoyance with, and interference by, aircraft noise, an alternative is recommended, namely the number of noise events above selected noise levels so that laypeople can better understand the extent of noise. The research is based on a questionnaire survey of households affected by aircraft noise around OR Tambo International Airport near Johannesburg. The results indicate that levels of annoyance and disturbance across a number of normal household activities are positively related to the number of noise events recorded, irrespective of noise levels above 60 dB.

Implementation of environmentally friendly measures at Tallinn Airport

Abstract: This paper aims at studying the problems of aviation noise and air, soil and water pollution in Tallinn Airport and the implementation of measures to make the airport more environmentally friendly. At present Tallinn Airport has two stationary noise level monitoring terminals and one mobile terminal for metering and modelling the noise level caused by aircraft taking-off and landing. Research shows that Tallinn Airport has not yet exceeded the noise limits stipulated by regulations. The area surrounding Tallinn Airport has been divided into four noise zones. Zone 1, where the noise level does not exceed 55 dB, is suitable for a majority of types of buildings, whereas Zone 4, where the noise level exceeds 70 dB and the highest level measured was 105 dB, is absolutely unacceptable as a building area. In recent years the number of flights flying over the residential areas of Tallinn has been reduced significantly, i.e. the number of flights taking off from runway 26 and landing on runway 08. In suit...

Implementation of a thrust reverse noise detection system for airports

Abstract: A thrust reverse noise detection methodology for airports is developed and tested in terms of meeting the restrictions at Madrid-Barajas airport. The detection is based on thresholds applied to the sound power level time histories estimated using a microphone array and an inverse sound propagation model. The two sound events detected are classified as landing and thrust reverse to complete the identification of thrust reverse activation. The methodology performs well especially in the detection stage because the estimation of sound power level enhances the sound events and their separation, even if landing and thrust reverse are close to each other. The implementation of the TREND tool has error rates lower than 10%.

Slat Noise Assessment from Airbus A340 Flyover Phased-Array Microphone Measurements

Abstract: To predict and optimize the noise impact of aircraft traffic airframe noise needs to be described by simple but reliable acoustic models. The present work is focused on the assessment of slat noise from Airbus A340 flyover noise measurements using a ground microphone phased array. A recently developed beamforming-based deconvolution technique for moving sources is used. This methodology enables to spatially separate the various airframe noise sources over a range of more than 10 dB and to provide their individual de-Dopplerized acoustic spectra. Slat noise spectra and directivity patterns are computed for two flight velocities: 150 and 175 kt. The results are compared to predicted noise levels given by a popular semi-empirical model based on static slat noise measurements at reduced scale in a wind tunnel. Despite both numerous uncertainties of real flyover noise tests and the inaccurate reproduction of slat devices at model scale, similar characteristics of slat noise are obtained.

Using the effect of alcohol as a comparison to illustrate the detrimental effects of noise on performance.

Abstract: The aim of the present research is to provide a user-friendly index of the relative impairment associated with noise in the aircraft cabin. As such, the relative effect of noise, at a level typical of an aircraft cabin was compared with varying levels of alcohol intoxication in the same subjects. Since the detrimental effect of noise is more pronounced on non-native speakers, both native English and non-native English speakers featured in the study. Noise cancelling headphones were also tested as a simple countermeasure to mitigate the effect of noise on performance. A total of 32 participants, half of which were non-native English speakers, completed a cued recall task in two alcohol conditions (blood alcohol concentration 0.05 and 0.10) and two audio conditions (audio played through the speaker and noise cancelling headphones). The results revealed that aircraft noise at 65 dB (A) negatively affected performance to a level comparable to alcohol intoxication of 0.10. The results also supported previous research that reflects positively on the benefits of noise cancelling headphones in reducing the effects of noise on performance especially for non-native English speakers. These findings provide for personnel involved in the aviation industry, a user-friendly index of the relative impairment associated with noise in the aircraft cabin as compared with the effects of alcohol. They also highlight the benefits of a simple countermeasure such as noise cancelling headphones in mitigating some of the detrimental effects of noise on performance.

Efficient use of an allotted airport annual noise budget through minimax optimization of runway allocations

Abstract: This article presents the development of a runway allocation planning tool that seeks to maximize the permissible number of flight operations into and out of an airport within a given annual noise budget. Although the model that underlies the planning tool is generic in nature, the tool has been customized for application to a specific airport, namely, Amsterdam airport Schiphol in the Netherlands. The noise budget regulations applicable at Schiphol stipulate limits on the annual cumulative noise loads at a large number of enforcement points arranged around the airport. To ensure an equitable distribution of the cumulative noise load at the enforcement points, an efficient allocation and distribution of the annual flight movements over available runways and routes is required that takes weather induced restrictions into account. To this end, a linear programming optimization formulation has been developed that implements a minimax performance criterion that aims to minimize the maximum cumulative noise load value occurring at any of the enforcement points. The numerical results obtained for the operational year 2005 clearly demonstrate the potential of the tool to maximize the yearly number of flight movements within the assigned noise budget.