Technology for a Quieter America (2010) / Chapter Skim
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5 Technology
5 Technology
Pages 55-88
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From page 55... ...
the former has been deemed a national priority, while the The noise heard when an airplane flies overhead comes latter has received less attention. Resources allocated for from many sources, but the main contributors are engine noise reduction are not always commensurate with noise noise and airframe noise.
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From page 56... ...
NASA Aircraft Noise: Source, Propagation, and Noise Impact FIGURE 5-1 Breakdown of typical noise sources for fixed-wing aircraft. Source: Posey (2008)
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From page 57... ...
The u.S. NOISE REDuCTION PROgRAMS FAA sponsors aviation noise R&D in noise measurement, The FAA and NASA have primary responsibility in the noise effects, interrelationships between noise and pollutant United States for R&D on aviation noise.
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From page 58... ...
The strategic plans for the National Airspace third phase, QTD3, is in the planning stages at Boeing. System indicate how each agency's R&D will contribute Over the years the FAA has defined requirements for to meeting noise reduction goals, which are designed to the reduction of aircraft noise emissions in terms of stages reduce public exposure to aviation noise primarily by re - (1–4)
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From page 59... ...
. Noise Reduction Objectives and Technology Paths FIGURE 5-7 Noise reduction objectives and technology plans set by ACARE.
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From page 60... ...
2008. Summary of the Aircraft Noise Day of the CAETS with low-speed, low-noise exhaust jets at takeoff and Workshop on Transportation Noise Sources in Europe, June 2–4, 2008, on ascent and then can be optimized for minimum fuel Southampton, United Kingdom.
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From page 61... ...
. Zero-Splice Passive Liner Ultra High Bypass Ratio Gear Box FIGURE 5-9 Engine/nacelle noise reduction technologies.
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From page 62... ...
. Figure_5-10.eps bitmap FIGURE 5-11 Negatively scarfed intake reflects fan noise away from the ground.
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From page 63... ...
By the end of VITAL, there should be a noise reduction of 8 dB per aircraft operation and an 18 percent reduction in carbon dioxide emissions, compared to engines in service prior to 2000. To reduce engine noise, very high bypass ratio engines with novel low-noise, low-speed fan designs are being studied.
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From page 64... ...
next 20 years, newly designed aircraft are likely to be intro- For NASA to achieve its goals of aircraft noise of 42 duced at a rapid rate. These aircraft will likely be based on EPNdB cumulative below Stage 3 for the N+1 generation current aircraft but designed to achieve significant reductions aircraft, considerable research will be needed in the follow ing areas: • target next-generation single aisle • ultra-high-bypass engines TABLE 5-1 Team Members Available to Work on • noise reduction technologies for fans, landing gears, European Noise Reduction Programs and propulsion airframe aeroacoustics X-3 Team Partners Country • l ightweight acoustic treatment in multifunctional structures Ain Shams University Egypt Alenia Italy ANOTEC Spain A2 Acoustics Sweden Budapest University of Technology and Hungary Economics (U.T.E.)
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From page 65... ...
Present departure with the new technologies in sufficient numbers to achieve and arrival procedures, which were developed when a limtargeted reductions in exposure to aviation noise. ited range of navigational aids was available, are far from If the FAA and NASA's noise reduction goals are not met, optimal from an environmental point of view.
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From page 66... ...
as people become more affluent. The implication for the This DNL for road traffic noise is expected to "highly aviation noise research community and government agencies annoy" almost 30 percent of people exposed to it (Waitz et that must support this community is that they cannot afford al., 2007)
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From page 67... ...
. 40 percent or less of total noise emissions for light vehicles Noise levels can also be visualized using acoustic beam- is due to tire noise (Donavan et al., 1998)
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From page 68... ...
Federal policy explicitly forbids the selection of the capacity of an existing highway is planned, and if federal pavement type for noise abatement, largely because of confunds are being used, federal policy allows only five types cerns that it will not maintain a given level of noise reduction of noise abatement to be considered: traffic management, performance over the life of the highway project. such as speed limits or vehicle restrictions; alterations of the highway alignment away from sensitive receptors; barriers QuIETER PAVEMENTS in the form of sound walls or earthen berms; the creation of buffer zones along the highway; and sound insulation for Notwithstanding federal policy, because of the initial cost some public buildings.
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From page 69... ...
Surveys of many highway California. Initially, this produced a reduction of about pavements using measurements made on board the vehicle 6.5 dB in traffic noise levels measured alongside the freeway, near the tire/pavement interface demonstrate that the range and a level 6 dB lower than was predicted by the FHWA may be even greater than 13 dB (Donavan, 2006)
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From page 70... ...
Surfaces that are this overlay reduced traffic noise levels by 6 to 12 dB mea- ground or textured by dragging burlap over the uncured sured 15 meters from the freeway. Using TNM predictions, surface typically produce less textured surfaces and less this reduction was equivalent to a barrier height of 4 meters resultant noise.
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From page 71... ...
. FINDINgS AND RECOMMENDATION More people in the United States are impacted by road traffic noise than by aircraft noise.
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From page 72... ...
in estimate would be that at least 10 million people are impacted the United States -- with the exception of Amtrak's Northeast by rail transportation noise in the United States today. Corridor, where speeds of 150 mph are possible on limited sections of track in Massachusetts, Rhode Island, and New Noise Sources Jersey.
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From page 73... ...
. Very high sound levels are emitted from • Fan noise -- cooling fans, which are required for all horns on top of the locomotive for one-quarter mile propulsion systems, can be a major noise source, es- leading up to a grade crossing.
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From page 74... ...
This technology Treatment of Noise Sources is especially valuable for locating sources of aerodynamic Control at the source is generally the most cost-effective noise on HSTs. way to approach a noise problem.
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From page 75... ...
Full-scale testing of Because of the sheer size of the building industry, the designs is conducted on dedicated test tracks where large widespread educational efforts are needed and design stanmicrophone arrays are used to diagnose noise sources. dards must be readily understood if satisfactory acoustical Special conventional HSTs can be built that are capable conditions are to be achieved in buildings.
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From page 76... ...
the classification of building acoustics into six inter isolation between rooms, especially when painful procedures related areas: exterior noise, interior room finishes, interior are being performed. Unfortunately, the Institute of Medicine room noise levels, sound isolation between rooms, alarms did not include a discussion of the adverse effects of noise and other electroacoustical systems, and building vibration in hospitals in its influential report, To Err Is Human (IOM, (Cavanaugh et al., 2010)
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From page 77... ...
. The American National Standards Institute to 0.75 inches or less, which reduces the sound isolation of Committee S12, Noise, Working Group 44 Speech Privacy, the floor/ceiling interface.
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From page 78... ...
Some features of green buildings that are rently, sound produced by these units exceeds the American considered important for reasons other than acoustics include National Standards Institute (ANSI) recommended maxi - more use of natural lighting, natural ventilating systems, use mum sound pressure level of 35 dB(A)
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From page 79... ...
The Green Guide for Health Care vide opportunities for the performing arts in intimate, atand the Green Guide for Schools establish design objectives tractive performance spaces. Entertainment in the broadest for acoustical building characteristics, including reverbera- sense includes music, cinema, and theater but also dining tion, sound isolation, and ambient sound in building spaces and parks.
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From page 80... ...
The sound ing, but they cannot deal with all aspects of design. and sound quality of products is important for market accep Some modeling procedures are oriented toward describ- tance, and technology for improving sound and/or producing ing and analyzing mechanisms.
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From page 81... ...
Perhaps as a reac- sounds. Products for which such metrics profiles have been tion to the notion of product sound as product noise, the most used to correlate with jury study judgments of sound quality attention has been paid to metrics, such as A-weighted sound include washing machines, dishwashers, vacuum cleaners, pressure level, that measure noise exposure, annoyance, and cookers, and room air cleaners.
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From page 82... ...
Unfortunately, the The basic message is that issues of product sound are very correlation between any single metric and sound quality and complex and do not become simpler and easier to handle the outcome of jury studies has not been generally accepted because a product is simpler and less costly. Indeed, the by the acoustics community, so claims that one product has situation may be quite the opposite.
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From page 83... ...
an airplane to a ring frame) , the most efficient way to There are four major active noise control strategies: obtain global noise reduction is to mount a shaker at the attachment point and feed it by a control system to 1.
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From page 84... ...
Road traffic noise has been controlled and produce noise reduction of a jet engine exhaust. Finally, mostly by constructing noise barriers, but work is being done Fuller et al.
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From page 85... ...
" Aircraft Noise Reduction Project Cabell, R.H., N Schiller, J.H.
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From page 86... ...
Available online o f EC Funded Aircraft Noise Research: Networks and Research at http://www.bookmasters.com/marktplc/0076.htm. Projects.
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From page 87... ...
2002. Tire/Road Noise Sources and Genera Available online at http://www.noisenewsinternational.net/archies_idx.
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