Showing papers on "Aircraft noise published in 2009"

Exposure-response relationship of the association between aircraft noise and the risk of hypertension

Abstract: Noise is a stressor that affects the autonomic nervous system and the endocrine system. Under conditions of chronic noise stress the cardiovascular system may adversely be affected. Epidemiological noise studies regarding the relationship between aircraft noise and cardiovascular effects have been carried out on adults and on children focussing on mean blood pressure, hypertension and ischemic heart diseases as cardiovascular endpoints. While there is evidence that road traffic noise increases the risk of ischemic heart disease, including myocardial infarction, there is less such evidence for such an association with aircraft noise. This is partly due to the fact that large scale clinical studies are missing. There is sufficient qualitative evidence, however, that aircraft noise increases the risk of hypertension in adults. Regarding aircraft noise and children's blood pressure the results are still inconsistent. The available literature was evaluated for the WHO working group on "Aircraft Noise and Health" based on the experts' comprehensive knowledge in this field. With respect to the needs of a quantitative risk assessment for burden of disease calculations an attempt was made to derive an exposure-response relationship based on a meta-analysis. This association must be viewed as preliminary due to limitations which are concerned with the pooling of studies due to methodological differences in the assessment of exposure and outcome between studies. More studies are needed to establish better estimates of the risk.

Multilateration enhancements for noise and operations management

Abstract: Multilateration techniques are used to provide accurate aircraft tracking data for aircraft on the ground and in the vicinity of an airport. From this data, aircraft noise and operations management may be enhanced. Aircraft noise may be calculated virtually using track data in real-time and provided to a user to determine noise violations. Tracking data may be used to control noise monitoring stations to gate out ambient noise. Aircraft emissions, both on the ground and in the air may be determined using tracking data. This and other data may be displayed in real time or generated in reports, and/or may be displayed on a website for viewing by airport operators and/or members of the public. The system may be readily installed in a compact package using a plurality of receivers and sensor packages located at shared wireless communication towers near an airport, and a central processing station located in or near the airport.

Policy discourse, people's internal frames, and declared aircraft noise annoyance: an application of Q-methodology.

Abstract: Aircraft noise annoyance is studied extensively, but often without an explicit theoretical framework. In this article, a social approach for noise annoyance is proposed. The idea that aircraft noise is meaningful to people within a socially produced discourse is assumed and tested. More particularly, it is expected that the noise policy discourse influences people’s assessment of aircraft noise. To this end, Q-methodology is used, which, to the best of the authors’ knowledge, has not been used for aircraft noise annoyance so far. Through factor analysis five distinct frames are revealed: “Long live aviation!,” “aviation: an ecological threat,” “aviation and the environment: a solvable problem,” “aircraft noise: not a problem,” and “aviation: a local problem.” It is shown that the former three frames are clearly related to the policy discourse. Based on this observation it is argued that policy making is a possible mechanism through which the sound of aircraft is turned into annoyance. In addition, it is concluded that the experience of aircraft noise and, in particular, noise annoyance is part of coherent frames of mind, which consist of mutually reinforcing positions and include non-acoustical factors.

Jet Noise Modeling for Suppressed and Unsuppressed Aircraft in Simulated Flight

Abstract: This document describes the development of further extensions and improvements to the jet noise model developed by Modern Technologies Corporation (MTC) for the National Aeronautics and Space Administration (NASA). The noise component extraction and correlation approach, first used successfully by MTC in developing a noise prediction model for two-dimensional mixer ejector (2DME) nozzles under the High Speed Research (HSR) Program, has been applied to dual-stream nozzles, then extended and improved in earlier tasks under this contract. Under Task 6, the coannular jet noise model was formulated and calibrated with limited scale model data, mainly at high bypass ratio, including a limited-range prediction of the effects of mixing-enhancement nozzle-exit chevrons on jet noise. Under Task 9 this model was extended to a wider range of conditions, particularly those appropriate for a Supersonic Business Jet, with an improvement in simulated flight effects modeling and generalization of the suppressor model. In the present task further comparisons are made over a still wider range of conditions from more test facilities. The model is also further generalized to cover single-stream nozzles of otherwise similar configuration. So the evolution of this prediction/analysis/correlation approach has been in a sense backward, from the complex to the simple; but from this approach a very robust capability is emerging. Also from these studies, some observations emerge relative to theoretical considerations. The purpose of this task is to develop an analytical, semi-empirical jet noise prediction method applicable to takeoff, sideline and approach noise of subsonic and supersonic cruise aircraft over a wide size range. The product of this task is an even more consistent and robust model for the Footprint/Radius (FOOTPR) code than even the Task 9 model. The model is validated for a wider range of cases and statistically quantified for the various reference facilities. The possible role of facility effects will thus be documented. Although the comparisons that can be accomplished within the limited resources of this task are not comprehensive, they provide a broad enough sampling to enable NASA to make an informed decision on how much further effort should be expended on such comparisons. The improved finalized model is incorporated into the FOOTPR code. MTC has also supported the adaptation of this code for incorporation in NASA s Aircraft Noise Prediction Program (ANOPP).

Bluff Body Noise Control Using Perforated Fairings

Abstract: Landing gears of commercial aircraft make an important contribution to total aircraft noise in the approach configuration. Using fairings to shield components from high-speed impingement reduces noise. Furthermore, perforating these fairings has been confirmed by flight tests to enable a further reduction. A fundamental study has been performed to investigate and optimize the benefits of bleeding air through the fairing by application of perforations. Experiments have been performed with a simplified fairing–strut combination to clarify the influence of perforations on flow behavior and acoustics. The fairing self-noise is reduced significantly by breakdown of the vortex shedding process, resulting in a reduction of the associated broadband noise level. A redistribution of the velocities is achieved depending on the applied porosity. However, increasing the porosity can result in adverse noise effects due to the bled mass flow washing the strut. Self-noise of the perforations manifests itself at higher frequencies, although scaling of this phenomenon with orifice diameter opens up the possibility to shift it above the upper limit of the audible range.

Assessment of Technologies for the Silent Aircraft Initiative

Abstract: The Silent Aircraft Initiative produced an aircraft design that combined many new and novel technologies to give a solution that was predicted to be fuel-efficient as well as extremely quiet. The study presented in this paper seeks to assess the benefits and penalties of each of the proposed technologies. A method has been developed that estimates the overall change in fuel consumption and engine noise caused by modifications to an aircraft design. The method sizes a propulsion system for a specified design and determines adjustments to the cruise performance based on changes in the engine components, the installation system, and system weight. The offdesign performance is also calculated so that the noise can be estimated. The method has been applied to show what contribution each silent aircraft technology made to the overall goal of the project. It also shows the tradeoffs between noise and fuel consumption for various technologies and indicates that there are configurations that can achieve both lower fuel burn and lower engine noise. The method has been used to identify a low-risk configuration of the silent aircraft, for which a new design is presented.

Noise-Source Separation Using Internal and Far-Field Sensors for a Full-Scale Turbofan Engine

Abstract: Noise-source separation techniques for the extraction of the sub-dominant combustion noise from the total noise signatures obtained in static-engine tests are described. Three methods are applied to data from a static, full-scale engine test. Both 1/3-octave and narrow-band results are discussed. The results are used to assess the combustion-noise prediction capability of the Aircraft Noise Prediction Program (ANOPP). A new additional phase-angle-based discriminator for the three-signal method is also introduced.

An Allocation Approach to Investigate New Aircraft Concepts and Technologies on Fleet-Level Metrics

Abstract: Aircraft noise and emissions have gained importance in recent environmental discussions. This paper presents the development of an allocation tool that assesses how new aircraft concepts and technologies impact fleet-wide emissions and noise by computing fleetlevel metrics such as direct operation cost (DOC), CO2 emissions, LTO NOX emissions and total area under the 65db noise contour. By modeling 12 different aircraft and a 102airport network, the tool is able to quickly assess if an aircraft fleet can feasibly be allocated throughout the network to minimize direct operating costs and still maintain a given level of emissions. Initial results indicate that if 2005 emission levels are desired in 2015 and beyond, the efficiency of aircraft must increase or the amount of passengers served must decrease.

Preliminary Design for Embedded Engine Systems

Abstract: This paper presents a collaborative research program to advance the analysis and design capabilities for embedded engines in Blended Wing Body Boundary Layer Ingesting (BWB- BLI aircraft. Embedded engine propulsion systems for hybrid wing/body aircraft face several key technical issues stemming from the ingestion of the low-momentum boundary layer to the close coupling of the airframe and propulsion systems in ways that challenge current design procedures and require a system design perspective. To address these challenges, a new high performance flow-control-enabled embedded engine inlet was designed. The inlet bleed flow control actuation was integrated with the aircraft Environmental Control System (ECS), thus providing a viable robust inlet design with improved system performance while supplying the flow required by the ECS. Without flow control, a thick ingested boundary layer leads to high levels of distortion at the AIP plane and impacts the overall fan performance and operability. The impact of inlet distortion on fan performance was estimated through numerical simulations based on unsteady flow simulations. Of particular interest, is the increased flow unsteadiness in the fan passages and its associated detrimental impact on blade aeromechanics and acoustic responses. The proposed flow control solution is predicted to have significant reduction in the harmonic content associated with blade strain. In addition, reductions in total radiated acoustic power are predicted to be achievable, especially at well cut-on modes, significantly reducing aircraft noise at approach conditions. These results suggest that inlet flow control technology has the potential to address the challenges of BWB-BLI aircraft.

Flexibility in highway noise management

Abstract: The problem of noise management was taken as a key element of our life comfort. An adequate noise mitigation plan must be elaborated and implemented for a number of potential noise sources. The general idea of FLENO‐MA2 (FLExibility NOise MAnagement for A2 POZNAN BY‐PASS) advisory system was based on flexibility options situated on different management levels. In the recent years, two significant noise sources have been established in Poznan agglomeration: POZNAN BY‐PASS A2 as a part of A2 highway (BERLIN‐MOSCOW) and the NATO aircraft base in Krzesiny. Both are situated in the urban area of Poznan city. Special emphasis will be placed on flexibility noise mitigation options as an example of operational decision‐aid. However, finding a compromise solution based on diffused (using the Internet) information about the noise map (will be present in the near future) is the second goal of this system.

Trajectory management for aircraft noise mitigation

Abstract: This paper gives an overview of aircraft trajectory management aimed at producing noise abatement procedures. Area Navigation (RNAV) concepts play an important role in the design of flexible and, therefore, noise friendly depart or approach procedures. In addition, the lowest dispersion of RNAV tracks help to contain noise footprints in a smaller area if compared with footprints that are produced when conventional procedures are flown. However, RNAV turns still produce a significant amount of dispersion because of different aircraft performance and different Flight Management Systems (FMS) implementation. Noise exposure can be also mitigated if the aircraft trajectory is conveniently modified in the vertical plane. In this work, a brief overview of different lateral and vertical noise abatement strategies is given. Theoretical optimal trajectories are also assessed presenting some results of previous research done by the authors. The annoyance produced by aircraft noise in different noise sensitive locations is taken as minimization objective. This annoyance not only takes into account the measured acoustic values but also other important aspects that will affect the perceived annoyance by the population. The concept of equitable trajectories is also presented, where noise annoyance is minimized in the worst noise sensitive location and not as an average value for all locations.

Three-Degree Decelerating Approaches in High-Density Arrival Streams

Abstract: The positive effects of continuous descent approac h (CDA) on aircraft noise, fuel consumption and emissions are evident. Nevertheless, the negative effect on capacity restrains continuous descent approaches from being used in high density traffic. A solution to this problem is the transfer of the separation t ask from the air traffic controller to the pilot. This paper discusses the feasibility of impl ementing the Three-Degree Decelerating Approach (TDDA) at high density traffic airports in a distance- or time-based self-spacing environment. In other research, time-based separation was implemented in the TDDA to prevent transient motions in the arrival stream res ulting in possible loss of separation caused by trajectory predictions of the leading aircraft b ased on previous states. For the same reason aircraft intent-based trajectory prediction of the lead aircraft in a distance-based scenario was introduced in this research. A fast-ti me simulation tool was developed to simulate arrival streams of different aircraft type s and weights that execute the TDDA in both self-spacing scenarios under actual wind condi tions. The simulation tool was used to quantify the performance differences between distance- and time-based self-spacing in terms of capacity, noise reduction, and loss of separatio n. For the time-based scenario no effects of leading aircraft on trailing aircraft could be iden tified. However, an increase in separation with a negative effect on the airport capacity to a ssure safe separation was required. In the distance-based self-spacing scenario a slow-down ef fect was observed, leading to a decrease in the noise reduction towards the end of the arriv al stream. The deteriorating noise reduction was solved by altering the initial separa tion between aircraft in the arrival stream. A sensitivity study showed that the TDDA performance in a distance-based scenario is not degraded dramatically by realistic deviations from the desired situation.

Reduction of Commercial Aircraft Noise Emission Around Airports. A New Environmental Challenge

Abstract: Noise abatement procedures (NAPs) are considered as a necessary measure for a balanced approach of noise control around airports. Their correct implementation depends upon many factors, which vary in operation and influence the efficiency of the NAPs. Any system, which defines the correct features of the NAPs for particular aircraft in specific conditions, would be useful for noise control. Thus, implementation of noise level monitoring systems, currently used around airports, gives a noise map in residential areas but cannot identify source frequencies and their impact on the environment. Consequently, this paper has been produced particularly to characterize the frequential aspect of aircraft noise emission. Its main objective is the analysis of the dominant frequencies emitted during approaches to the Lyon Saint-Exupery International Airport (France) having a negative impact on the population living around this airport. Thus, the results obtained make it possible to show, through an empirical model of aircraft noise, the effectiveness of this experimental work.

Integration and application of a tool chain for environmental analysis of aircraft flight trajectories

Abstract: The German Aerospace Center (DLR) is currently developing a tool chain for the environmental analysis of aircraft flight trajectories. The presented tool chain consists of tools for aerodynamic analysis, engine cycle modelling, flight simulation, and aircraft noise prediction. The aircraft geometry is not modified within the process but provided as an input. The implemented tools come from specialized DLR institutes, are harmonized in input/output format and are integrated into one fully automated analysis process. The PHX ModelCenter framework allows for a DLR-wide accessible server/client architecture. The new tool chain is applicable to evaluate arbitrary three dimensional flight trajectories. The focus of the presented work lies on the environmental analysis and optimization of approach and departure procedures. The predicted ground noise levels are compared to results from a dedicated DLR flyover noise campaign in 2009. A conventional approach, a steep approach, and a new three dimensional approach procedure have been flight tested with DLR’s flying testbed ATTAS. The new procedure is referred to as Helical Noise Abatement Procedure (HeNAP) due to its helix shape. The ground noise measurements confirm the predicted noise concentration and relocation along the steep approach and the HeNAP compared to the conventional approach procedure.

Validation of DLR's sound shielding prediction tool using a novel sound source

Abstract: This paper is concerned with an experimental validation methodology for DLR’s acoustic shielding prediction boundary element code BEMPAR. This code in turn will be integrated into the overall aircraft noise prediction tool PANAM of DLR. The presented validation concept is based on a novel laser-based sound source. Almost perfect monopole-type test signals may be produced with a frequency content up to roughly 100kHz in combination with a very small source extension. These characteristics make this technique especially attractive for shielding/installation tests, which typically have to be performed at relativey small scale. BEMPAR is a boundary element code (BEM) which solves for the scattered pressure field. Three generic test cases are evaluated, a circular plate, a long cylinder and DLR’s low noise aircraft (LNA-1) nacelle model. The outcome of this investigation clearly demonstrate the potential of BEMPAR for the prediction of installation eects.

Aircraft Noise: A Toolkit for Managing Community Expectations

Abstract: This guidebook should be of interest to airport managers and other staff from airports of all sizes who are responsible for responding to neighboring communities regarding aircraft noise issues It provides guidance on how best to improve communications with the public about issues related to aircraft noise exposure Specifically, the guidebook presents best practices that characterize an effective communications program and provides basic information about noise and its abatement to assist in responding to public inquiries It also suggests tools useful to initiate a new or upgrade an existing program of communication with public and private stakeholders about noise issues An accompanying CD-ROM (CRP-CD-70) contains a toolkit with examples of material that has been successfully used to communicate information about noise, as well as numerous guidance documents about noise and communications that have seldom been brought together in the same resource

Computational AeroAcoustics of a Realistic Co-Axial Engine in Subsonic and Supersonic Take-Off Conditions

Abstract: The present work is devoted to the numerical simulation of acoustic emissions characterizing turbojet engines, a subject that is relevant of the more general purpose of aircraft noise prevision and reduction. More precis ely, we explore here the ability of a structured CAA (Computational AeroAcoustics) method/solver to address complicated problems of engine noise prediction. With that end, and by using the ONERA’s CAA solver sAbrinA.v0 , we conduct realistic calculations of aft fan nois e emission, which involve both a full-3D exhaust geometry (with its pylon / internal bifurcations) and typical fan noise modal contents (high azimuthal order / frequency). The re sults highlight how far the installation / refraction effects induced by the complex geometry / flow of an engine can affect its fan noise emission. Results also tend to demonstrate that bot h the here used CAA method and solver are mature enough to face out industrial-like engin e noise problems.

Fan Noise Prediction with Applications to Aircraft System Noise Assessment

Abstract: This paper describes an assessment of current fan noise prediction tools by comparing measured and predicted sideline acoustic levels from a benchmark fan noise wind tunnel test. Specifically, an empirical method and newly developed coupled computational approach are utilized to predict aft fan noise for a benchmark test configuration. Comparisons with sideline noise measurements are performed to assess the relative merits of the two approaches. The study identifies issues entailed in coupling the source and propagation codes, as well as provides insight into the capabilities of the tools in predicting the fan noise source and subsequent propagation and radiation. In contrast to the empirical method, the new coupled computational approach provides the ability to investigate acoustic near-field effects. The potential benefits/costs of these new methods are also compared with the existing capabilities in a current aircraft noise system prediction tool. The knowledge gained in this work provides a basis for improved fan source specification in overall aircraft system noise studies.

Techno-economic and environmental risk assessment of innovative propulsion systems for short-range civil aircraft

Abstract: Aircraft are thought to contribute about 35% (IPCC, 1999) to the total radiative forcing (a measure of change in climate) of all the human activities and this figure is forecaste to increase Future concerns for aviation’s role in climate change are mainly due to the envisaged continued growth in this sector Growth rates for emissions are less than those for traffic growth since fuel efficiency continues to improve over the years Despite regular improvements in fuel efficiency, emissions will carry on increasing and several solutions need to be found The growth of air travel as well and its effect on world economics is hampered by local opposition to aircraft noise Besides, restrictions on night take-off and landing because of aircraft noise levels leads to a negative impact on the revenues of Europe’s airlines and often results in non-European over-night airport refuelling stops According to ACARE (Strategic Research Agenda, 2005), the sustainable development of air transport depends on achieving a significant across-the-board reduction in environmental impact, in terms of greenhouse gases, local pollution and noise around airports Over the past 40 years the introduction of new technology has mitigated the environmental impact of aviation growth, but at the expense of increasing operating costs Consequently, in order to make aviation more sustainable environmentally and economically, radically innovative turbofans need to be considered and optimised at the aircraft level Based on the above, this PhD project addresses the following research questions: • The potential of different novel propulsion systems with enhanced propulsive efficiency (using advanced, contra-rotating and geared turbofans) and thermal efficiency (using intercooled and recuperated, and constant volume combustion turbofans) to meet future environmental and economical goals • The trade-offs to be made between noise, emissions, operating cost, fuel burn and performance using single- and multi-objective optimisation case study In order to achieve this, a multidisciplinary design framework was developed which is made up of: aircraft and engine performance, weight, cost, noise, emissions, environment, and economics and risk models An appropriate commercially available optimiser is coupled with this framework in order to generate a powerful aero-engine preliminary design tool The innovative turbofans were benchmarked against the baseline turbofan at the aircraft level using the A320 The multi-objective trade case study for minimum fuel burn, NOx emissions, engine direct operating cost (DOC) and noise proves that these engines are feasible to meet future noise and emissions requirements for an acceptable cost of ownership The key driver to lower engine DOC is a considerable fall in fuel consumption Nevertheless, acquisition and maintenance cost rise owing to hardware complexity Consequently, further study of these engines is recommended as their environmental performance potential is considerable

Estimation of Effects of Transportation Noise Annoyance on Residential Satisfaction

Abstract: The present study assesses the impacts of transportation noise (air, road and rail) on residential satisfaction, an important indicator of subjective well-being To this effect a structural equation model is specified that estimates the relationships between objective variables, (transportation) noise annoyances and residential satisfaction An existing dataset is used to estimate the model (N=10,858) The survey to acquire these data was conducted in 1996 among the population living within a 25-kilometer radius of Amsterdam Schiphol, the largest airport in the Netherlands The specified model fits the data well Based on the results it is concluded that aircraft noise annoyance is the most important determinant of residential satisfaction followed by aircraft noise exposure, neighbor noise annoyance, slow road traffic noise annoyance ( 31 miles p/h), railway noise annoyance and construction noise annoyance on residential satisfaction are found to be insignificant, controlled for the other variables in the model The findings are discussed in light of existing theory and previous empirical research

Enhanced Modeling of Aircraft Taxiway Noise—Scoping

Abstract: Aircraft taxi noise acoustic sensitivity studies were conducted to document the importance of the modeling elements within INM and AEDT: source noise, operations, and environmental propagation. Sensitivity studies decoupled the taxi noise into the three areas and exercised each element independently. Limited opportunistic commercial aircraft taxi operation acoustic measurements were conducted. Independent taxi flight data recorder (FDR) information was queried to determine statistical engine and aircraft operational parameters. The sensitivity studies revealed the primary driver for prediction is source noise: level, spectra and directivity. A nominal taxi state NPD, spectral class and directivity database is suggested based on existing data augmented with measurements. There is sufficient capability in INM to support detailed taxi operations. Future improvements planned for AEDT will reduce user input burden. The propagation algorithms, primarily lateral attenuation are sufficient. Airport-specific considerations may necessitate inclusion of terrain, shielding and variable ground impedance. The measured acoustic data and FDR data were separate; therefore one could not quantify sensitivity of taxi noise to thrust. This identifies a need for a concurrent acoustic/FDR dataset. The study suggests modeling nominal taxi state in the short term with a comprehensive long term enhanced acoustic sensitivity to thrust capability.

Verification of two methods of railway noise propagation

Abstract: The noise maps of agglomerations comprise those of road traffic-, tram-, aircraft-, industrial- and railway noise. EU recommends the use of a few selected calculation methods for the estimation of noise: for road traffic noise - NMPB-Routes-96, for aircraft noise - ECAC.CEAC Doc 29, for industrial noise - ISO 9613-2 and for railway noise - Reken en Meetvoorschrijft Railverkeerslawaai 1996 (for tram noise - there is no specific computation method). However, the Member States can use their own computations methods provided that these methods have been positively verified. The results of the calculations using their own method and interim method must be compatible. In this paper, two methods of railway noise propagation are compared: the first one recommended by EU and the second one developed at the Adam Mickiewicz University in Poznan. The results obtained by the two methods are similar.

Aircraft noise and health of residents living in the vicinity of Frankfurt Airport

Abstract: In 2005 a field study on the effects of aircraft noise on annoyance, disturbances and health-related quality of life was done with residents living around Frankfurt Airport. Face-to- face studies with 2312 residents were carried out, for each address aircraft noise levels were calculated on the base of flight movements of the 6 busiest months of the year. This contribution deals with analyses of the data from this field study with regard to the relationship between aircraft noise level, reactions to aircraft noise (in particular noise annoyance), noise sensitivity and physical as well as mental health. The results do not support the assumption of a direct effect of aircraft noise exposure on physical and mental health. However, associations between noise annoyance, noise sensitivity and self-reported health could be observed. Three approaches may explain the observed relationships. According to the first approach, it is not the noise exposure itself but the psychological reaction to noise which leads to further health effects. The second model suggests that the assessed complaints, health diseases and noise sensitivity increase psychological reactions to noise like annoyance. The third approach combines the first two models and describes a recursive process of health complaints and noise sensitivity intensifying noise annoyance, which in the long run lead to further health effects.