Acoustic space filling curve metamaterials for grazing flow in Jet engine inlets
Time: 3:20 pm
Author: Jennifer Glover
Abstract ID: 1458
Acoustic metamaterials research has grown exponentially in the past 10 years driven by the advances in manufacturing and an increased understanding of damaging environment noise. 2020 was the first noise reduction target as set by Advisory Council for Aircraft Research and Innovation in Europe with a relative 50% decrease. This was missed by current Jet engine noise control technology; however, metamaterials offer an encouraging alternative. Space Filling Curves (SFC) have the potential to provide a lightweight, thin, high performance acoustic liner. SFC have a history in mathematical geometry dating back to the 1890s but are a comparatively new addition to acoustics. They are designed with a sub-wavelength curled cross-section creating a maze-like pattern which slows acoustic wave propagation through the liner enabling characteristics such as negative refraction and low frequency attenuation. This paper contains a comparison of some of the most promising SFC metamaterial acoustic liner designs, in terms of the fundamental theory of the design category and a discussion of the reflection, absorption and transmission characteristics in terms of a grazing flow conditions. Computer simulation and impedance tube based experimental testing compares the designs. The paper concludes with future application for aeroacoustics with particular focus on the engine inlet.
Operational noise optimization of aircraft approaches
Time: 11:40 am
Author: Bengt Moberg
Abstract ID: 1494
As the pilots slow the aircraft down and extend flaps and landing gear in preparation for landing the characteristics of the aircraft as a noise source changes. In the OPNOP project, the possibility to use this variation in noise generation to minimize noise at a specified location is examined. Such analysis requires an increased understanding about aircraft noise generation as the aircraft changes configuration and speed during the approach, where theoretical models available can be overly simplistic and of little use for this purpose. Using flight data from 113 actual Airbus A321 flights, and corresponding noise measurements on the ground, this study reports on the initial findings forming the foundation on which further analysis will be conducted. Intermediary findings relate to: a comparison between models and actual measurements, the distance variability to the runway for various flap selections and extension of the landing gear as well as a comparison between flight data and on-ground noise measurements. Captured data suggest that it should be possible to use speed and configuration recommendations to reduce noise over selected approach areas. Future research will include scenario generation and incorporate flight data from an earlier study to increase validity.
Virtual reality simulated aircraft flyovers: Influence of the landscape on the overall pleasantness of the environment.
Time: 11:20 am
Author: Romain Dedieu
Abstract ID: 1564
To give residents better understanding of the impact of future airport scenarios, a virtual reality application with sound simulation will be tested in the frame of the European ANIMA project. The set-up has been evaluated in laboratory before being used in real situation. This paper presents the laboratory experiment whose aim is to assess the applications relevance for simulating flyovers. Although the perceptual experiment is designed to test the influence of aircraft vision crossed with aircraft sound, this paper focusses only on the impact of the landscape where the flyovers are observed. Two landscapes (park and buildings) are presented to 60 participants, in balanced order, with 12 audio-visual stimuli in both landscapes. Participants had to rate four differential semantic scales. Globally there is no influence of the landscape on the overall pleasantness, but when looking at the individual answers, it appears that three groups of participants can be discriminated. The majority of people do not change their pleasantness ratings in both landscapes, but some participants prefer experiencing the flyovers in the park landscape because it is visually more pleasant, and others prefer the opposite because it is more annoying to be submitted to aircraft noise in a green park landscape.
High Lift Device Modifications for Reducing Airport Noise A Review
Time: 3:00 pm
Author: Benjamin Reydel
Abstract ID: 1610
Aircraft noise has been one of the top environmental issues at and near airports across the country because of its negative impact on communities. The growth of the nations air transportation system is restricted predominantly due to regulations on limiting aircraft noise generated around airports. Reducing aircraft noise will lead to wider community acceptance of new or larger airports, lower airline operating costs by reducing noise quota fees, and increase air traffic growth through operating more flights. One of the most significant contributors to aircraft noise, structural vibrations caused by air flow across its frame, are high lift devices. A review of high lift devices, such as flaps, and methods to reduce their noise levels will be presented. Solution reviews will focus on reducing flap trailing-edge scattering and flap side-edge vortices.
Evaluation method of military aircraft noise using AI analysis of aircraft images
Time: 7:00 am
Author: Etsushi Fujita
Abstract ID: 1668
In recent aircraft noise survey in Japan, noise data is associated with each aircraft by flight log or by radio information including transponder signals. Especially, above Tokyo metropolitan area, flight tracks are tangled extremely each other, therefore assessments from various perspectives such as departure / arrival airport, used runway, aircraft model, and operator have been demanded for determining noise policies. However, for military aircrafts, it is not easy to identify their information with the same way as commercial aircrafts, because their flight logs are not disclosed and many of them do not emit transponder signals like commercial aircrafts. Therefore, manned 24 hours survey around air bases have been necessary to obtain flight information of military aircrafts. In this paper, we propose an AI-based analysis using captured aircraft images for obtaining actual flight data of military aircrafts. In the past trials, we could determine the takeoff/landing time and the aircraft model by the above method. Associating these information and noise data measured at monitoring stations, details of noise characteristics around the air base can be clearly grasped. Advanced analysis of the causes of noise impact will lead effective and concrete countermeasures.
Enhancing Noise Management Strategy: Recommendations from the strategy literature.
Time: 2:20 pm
Author: Graeme Heyes
Abstract ID: 1722
Airports are required to manage noise impact owing to their requirement to obtain a social license to operate, and to comply with legislation such as the ICAO Balanced Approach and Environmental Noise Directive. Research has however shown that noise management actions and interventions often take a techno-centric approach, are implemented in silos, and that their success beyond noise metrics is rarely evaluated. Moreover, the success of Noise Action Plans in driving long-term noise management outcomes has also been critiqued at a number of levels. In the context of this background, this paper outlines the case for more strategic approaches to noise management and, drawing on the academic strategic literature, outlines approaches to developing such strategies that can be followed by airports. The aim of such approaches is to complement existing noise management guidance by providing step-processes that can aid airports in developing robust, repeatable, evaluable, and successful noise management strategies that are consistent with wider airport strategy and that are sympathetic to the needs of airport residents.
Noise assessment of taxibotted versus conventional taxiing operations using a phased microphone array
Time: 7:20 am
Author: Bieke von den Hoff
Abstract ID: 1765
In sustainable aviation the focus is mostly applied to the greenhouse gas emissions during flight. However airports have an increasing interest in reducing emissions during ground operations such as taxiing for example to improve the local air quality. Amsterdam Airport Schiphol started a pilot for sustainable taxiing with a pilot-controlled hybrid-electric aircraft towing vehicle called TaxiBot in 2020. The COVID-19 pandemic created an opportunity for extensive operational testing on a near-empty airport. Due to the low background noise levels in this situation, also a noise assessment of taxiing with the TaxiBot versus conventional two-engine taxiing was performed. This assessment can be used to evaluate the noise levels to which ground workers or neighbouring communities are exposed due to TaxiBot operations. For the noise measurements a phased microphone array was used, which allowed not only for a noise level and directionality assessment, but also for noise source identification. This paper compares the noise emissions and noise sources between a taxibotted and conventional taxiing operation. The results show that a taxibotted taxiing operation produces significantly lower noise levels. Additionally, acoustic imaging shows that the TaxiBot engine is the main noise source for a taxibotted pass-by manoeuvre.
Time: 12:00 pm
Author: Barbara Ohlenforst
Abstract ID: 2023
The current study presents the analysis of seven airport exemplification case studies undertaken in the European project Aviation Noise Impact Management through Novel Approaches ANIMA. Best practices related to aircraft noise management at airports in individual airport contexts were implemented and evaluated. Case studies on communication and community engagement in airport noise management were investigated at Heathrow (Great Britain), Ljubljana (Slovenia) and Rotterdam The Hague (The Netherlands) airports. For Zaporizhzhia (Ukraine) and Iasi (Romania) airports, the implementation of interventions related to land use planning was examined. The interdependencies between noise and emissions were studied for Cluj (Romania) and Catania (Italy) airports. All case studies were performed under the scope of the corresponding national legislation and guidelines. Individual characteristics of airport operations were taken into account. The case studies were aligned with expectations and priorities of all involved stakeholders, such as representatives of airport operators, local communities, civil aviation authorities and policy makers. The efficacy of the noise management case studies is assessed in terms of: the capacity to negotiate consensus outcomes, the extent to which noise impact reductions were achieved; and the participants satisfaction with the process and outcomes. Experience gained from these studies will be used to distill best practices for future intervention.
Study on aircraft noise directivity of behind the start of takeoff roll
Time: 6:00 am
Author: Toshiyasu Nakazawa
Abstract ID: 2330
This paper discusses aircraft noise directivity behind the start of takeoff roll. Aircraft noise has the radiation directivity because of aircraft engine mount position and the engine noise directivity. Thus, lateral noise directivity correction is recommended in airport noise calculation guidelines such as ECAC Doc.29 and ICAO Doc9911. In these guidelines, the directivity of flyover noise and the directivity at the start of takeoff roll on ground are prepared separately. A 90-degree dipole model is used for the directivity of the flyover noise, and another similar directivity is used for the directivity behind the start of takeoff roll. It is necessary to properly evaluate the directivity behind the takeoff roll because it has a large contribution to noise calculation of the vicinity of the airport. Therefore, we measured aircraft noise behind the start of takeoff roll with sound level meters placed half-concentrically around Narita Airport in Japan. From these measurement results, various types of aircraft noise directivity behind the takeoff roll are examined and considered the effects of weather conditions such as wind direction. Finally the differences from existing models are compared.
Towards predicting noise-power-distance curves for propeller and rotor powered aircraft
Time: 11:00 am
Author: Daniel Amargianitakis
Abstract ID: 2555
Propeller and rotor based propulsion systems are the dominating choice of power delivery system in the upcoming Urban Air Mobility market. Fully electric air-taxis (car sized vehicles with Vertical Take-off and Landing, VTOL, capabilities) concepts are using the benefits of the scalable properties of electric motors to distribute propulsor units all over the airframe. The large variety of concepts and configurations of these vehicles poses a serious issue in predicting noise generated on the ground. The need for a high-level model to aid in acoustic decision making is evident. Through the demonstrated methodology of computationally deriving Noise Power Distance curves for conventional turbo fan aircraft, this paper delivers the capability of dealing with propeller propulsion systems and the associated propeller tonal noise sources to generate the NPDs and therefore noise exposure maps. The aims can be broken down into two objectives: a) demonstrate the capabilities of the proposed propeller harmonics noise scaling laws to calculate noise variation from a baseline scenario and b) incorporate the scaling components into the larger capability of producing noise exposure contours, by the means of computationally deriving NPD curves for propeller powered aircraft. Preliminary NPD curves for General Aviation sized propeller power aircraft are generated and discussed.
Sound arrival direction and acoustic scene analysis for the monitoring of airport noise
Time: 6:20 am
Author: Keishi Sakoda
Abstract ID: 2753
The authors have developed a sound direction detection method based on the cross-correlation method and applied it to automatic monitoring of aircraft noise and identification of sound sources. As aircraft performance improves, noise decreases, and people are interested in and dissatisfied with low-level noise aircraft, especially in urban areas where environmental noise and aircraft noise combine to complicate the acoustic environment. Therefore, it is necessary to monitor and to measure not only aircraft noise but also environmental noise. Since our surveillance is aircraft noise, it is important to analyze noise exposure from acoustic information rather than trucks or images. In this report, we will look back on the development process of this sound direction detection technology, show examples of helicopters and application examples of acoustic scene analysis to high-altitude aircraft, and consider the latest situation realized as acoustic environment monitoring. We believe that this analysis will make it easier to understand the noise exposure situation at the noise monitoring station. It also describes the future outlook for this method.
Daily fluctuations in aircraft noise exposure around civil airports and military airfields in Japan
Time: 6:40 am
Author: Koichi Makino
Abstract ID: 2984
In Japan, yearly average of (day-evening-night sound level) as cumulative noise index has been adopted in national noise guideline of "Environmental Quality Standards for Aircraft Noise." Daily flight movements at civil airports are almost stable because of scheduled airline flight. On the other, daily total flight movements at military airfields greatly change day to day because of training flights, etc. Thus, noise exposure around the airport may change significantly from day to day due to change of flight movement. This paper shows examples of fluctuations, frequency distribution and deviation of daily using aircraft noise monitoring data around civil airports and military airfields. In the case of civil airports, standard deviation of daily was less than 5 dB at the monitoring stations where the yearly average of were about 55 dB or more. However, the standard deviation of daily increased 10 dB or more in some cases at points where yearly average of less than 55 dB. Furthermore, in the case of military airfields, the standard deviation of daily were 5 dB or more for all monitoring stations.
Development of Fly Neighborly helicopter model specific operational noise abatement guidance from acoustic flight test data
Time: 12:20 pm
Author: Juliet Page
Abstract ID: 3210
Improved helicopter noise abatement guidance has been developed based on acoustic test data acquired by NASA, FAA and Volpe in support of the Helicopter Association International (HAI)s Fly Neighborly Program. This higher fidelity material was developed to supplement previous training programs based on pilot and operator feedback. The manner of presentation allows pilots to readily interpret the directional noise emission of their vehicle at different operating conditions. Flight path, airspeed, approach descent rate, and deceleration rate can be assessed to optimize flight patterns both during the pre-flight planning stage and in real time during flight operations in response to local conditions and events. The resultant sound directivity would be displayed as colored noise exposure contours overlaid onto a map of the area in the vicinity of the helicopter. New Fly Neighborly training modules have been developed utilizing directional operational noise plots based on Volpes Advanced Acoustic Model (AAM) modeling with empirical sound sphere data from dedicated US Government helicopter flight tests. This paper will describe the acoustic analyses and will present the updated noise guidance for the AS350, AS365, AW139, Bell 205, Bell 206, Bell 407, R-44, R-66 and S-76D helicopters.
US Federal Aviation Administration Neighborhood Environmental Survey: Study Design and Survey Methodology
Time: 2:40 pm
Author: Eric Jodts
Abstract ID: 3300
As part of the agencys broader noise research program, the Federal Aviation Administration (FAA) has undertaken a multi-year research effort to quantify the impacts of aircraft noise exposure on communities around commercial service airports in the United States (U.S.). The overall goal of the study was to produce an updated and nationally representative civil aircraft dose-response curve; providing the relationship between annoyance and aircraft noise exposure around U.S. airport communities. To meet this goal, the FAA sponsored a research team to help design and conduct a national survey, known as the Neighborhood Environmental Survey (NES). Residents from households around 20 airports were selected for participation in the survey; the detailed sampling process is covered in another paper. Two survey instruments were administered to adult residents within the NES: a mail questionnaire and a follow-up telephone interview for the mail respondents. The mail survey was administered to samples of individuals in the selected airport communities in six separate waves over a 12-month period starting in October 2015. All mail survey respondents were invited to complete a follow-up telephone interview, which asked detailed questions on several areas including respondents opinions on noise, exposure to aircraft noise, relationship to the airport, concerns about aircraft operations, views on airport community relations, among others. Analysis of the survey responses on annoyance levels and the associated DNL was used to estimate dose-response curves for each individual airport and a national dose-response curve. The national dose-response curve created from the mail questionnaire shows considerably more people are highly annoyed by aircraft noise at a given noise exposure level compared to historical FICON data. This paper provides a detailed discussion of the survey design and methodology. Additional information describing the motivation to conduct the NES and how its findings will help inform ongoing work to address aircraft noise concerns; and the noise methodology are provided in companion papers.
Sound source modelling by nonnegative matrix factorization for virtual reality applications
Time: 11:00 am
Author: Christian Dreier
Abstract ID: 1742
Auralization is a suitable method for subjective noise evaluation of virtual prototypes. A basic requirement is the accurate modelling of the sound sources. This includes a dynamic and parametric description at multiple operating conditions. In the case of wave propagation including flow, such as aircraft or vehicle noise, aeroacoustics or fluid dynamics simulations are practically limited to the acoustic near field due to high computational costs. Especially challenging are simulations of rotating systems, such as fan noise radiation. For better applicability, the proposed method is based on in-situ recordings of flyovers. The processing chain compensates for source position and movement as well as atmospheric and soil damping effects on recorded data. The compensated source signal is decomposed into partial sources in spectro-temporal domain with nonnegative matrix factorization (NMF) and can optionally be enhanced by physically-based source information. The format of the source model obtained is ready to use for dynamic sound synthesis in real-time virtual reality applications.