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Introduction
Published in Milan Janić, System Analysis and Modelling in Air Transport, 2021
The aircraft noise is mainly generated in the vicinity of airports by the aircraft take-offs and landings. In addition to the absolute levels of noise by particular aircraft types, the number of population exposed to the certain levels of noise can be an indicator of the air transport system sustainability respecting to noise impact. In general, regarding the aircraft noise, the US FAA has established the level of DNL (Day-Night Level) of 65 dBA as the threshold or “significant” (US DOT/FAA, 2015). The EEA (European Environmental Agency) has established the threshold level of (Lden) (Level day-evening-night) of 55 dBA. Above these levels, the aircraft noise is considered to be incompatible with residential areas. Table 1.6 shows the population exposed to the aircraft noise around the U.S. airports over the specified period of time.
Principles of Noise Control
Published in Junbo Jia, Jeom Kee Paik, Engineering Dynamics and Vibrations, 2018
One of the first steps in any noise control project is to understand the nature of the problem. Noise may be a problem for many reasons. There may workers who are overexposed to noise and are having their hearing damaged. There may be an environmental noise problem where neighbors and surrounding communities are annoyed by noise from a factory or other industrial area. Most industrialized countries have regulations concerning the overexposure of workers that define limits and impose penalties for failing to protect workers (Lie et al., 2015; ConchaBarrientos et al., 2004). There are a wide range of national and local regulations with regard to noise in communities. In many cases these are generic limits related to sleep disturbance or the disturbance of typical activities in the home (International Institute of Noise Control Engineering, 2009; Ontario Ministry of the Environment, 2013). In other cases, these regulations are specific to the source. For instance, many countries regulate and require monitoring aircraft noise near an airport (Transportation Research Board of the National Academies, 2008; Koopmann and Hwang, 2014; UK Environmental Research and Consultancy Department of the Civil Aviation Authority, 2014). In other countries noise from traffic and trains are also specifically regulated (International Institute of Noise Control Engineering, 2009; International Institute of Noise Control Engineering Working Party on Noise Emissions Of Road Vehicles (WP-NERV), 2001; Japan Automobile Manufacturers Association, Inc., 2013).
Noise emissions from commercial aircraft
Published in Emily S. Nelson, Dhanireddy R. Reddy, Green Aviation: Reduction of Environmental Impact Through Aircraft Technology and Alternative Fuels, 2018
The commercial aviation enterprise has inevitable consequences for the environment. The most immediately obvious of these consequences is the noise experienced by the communities living around the airports. data suggest that aircraft noise continues to be the number one cause of the adverse community reaction to the expansion of airports and the associated increases in the air traffic. To limit the growth of the noise exposure problem, by international agreements, limits are placed on the level of noise that aircraft can generate when operating in and out of airports. To keep up with the growth of the commercial fleet, these limits are periodically revised downward by the International Civil Aviation organization (ICAO) based on technology forecasts and economic feasibility. once approved by the ICAO member countries, these new limits are adopted for implementation by the respective national regulatory agencies of the member countries. In the united States, the Federal Aviation Administration (FAA) is the responsible government agency for enforcing the aircraft noise limits. In addition, through other measures, like land-use management and changes to the operational procedures, the FAA seeks to reduce, over time, the number of people in the united States who are exposed to objectionable aircraft noise levels.
Health effects of transport noise
Published in Transport Reviews, 2023
David Welch, Daniel Shepherd, Kim N. Dirks, Ravi Reddy
Interestingly, a Swiss study of approximately 4.4 million participants found no association between aircraft noise and cardiovascular diseases overall, but reported significant risks for some cardiovascular outcomes such as myocardial infarction, heart failure and ischemic stroke (Heritier et al., 2017). The night ban on air traffic in Switzerland was offered as an explanation for the weaker overall association. This study also reported a significant association between railway noise and ischemic heart diseases and myocardial infarction. Road traffic noise was found to be significantly associated with all cardiovascular disease outcomes apart from stroke. A recent longer follow-up study found similar associations where, after adjusting for air pollution, road traffic and railway noise exposure were associated with the majority of cardiovascular disease-related mortality (Vienneau et al., 2022). A significant finding of this study was that exposure-response relationships increased from low noise levels, as much as 20 dB below the WHO guideline limits of 53 dB Lden for road traffic, 54 for railway, and 45 for aircraft.
Numerical investigation of unsteady flow past rudimentary landing gear using DDES, LES and URANS
Published in Engineering Applications of Computational Fluid Mechanics, 2018
Qing-Li Dong, He-Yong Xu, Zheng-Yin Ye
Landing gears are one of the most important contributors to modern airframe noise. During the landing process, the noise generated by landing gears can reach 25% of the total aircraft noise when the flaps are closed (Monclar, 2003), whereas for some wide-body jets such as the Boeing 777 and Airbus 340, the landing gear-induced noise can play a dominant role (Chow, Mau, & Remy, 2002). To some extent, the landing gear noise consists of broadband noise generated by unsteady vortex shedding, interactions of turbulent wakes between components, shear-layer breakdown and cavity noise from gear wheels. Each component interacts intensively with the surrounding air and forms a complex unsteady flow. Research has been attempted to measure the contributions of each component so that these measurements can then be used as a basis for the design of noise reduction for landing gears (Yokokawa et al., 2010). Recently, several new methods for noise reduction of landing gears have been investigated, such as fairings (Boorsma, Zhang, & Molin, 2010), porous meshes (Takaishi et al., 2017), optimized components, air curtains (Oerlemans & de Bruin, 2009), plasma actuators, vortex generators (Hao & Jia, 2016) and so on. Kennedy, Neri, and Bennett (2016) generally group these techniques into four categories based on how they function, including component enhancement, component smoothing, flow enhancement and flow deflection. Nevertheless, some of these techniques are still at a low technology readiness level due to highly unsteady flow around landing gears, making it difficult to study the noise by experimental means(Dobrzynski, 2010).