摘要 :
In a study conducted in the vicinity of Salt Lake City International Airport, community residents reported their annoyance with individual aircraft flyovers during rating sessions conducted in their homes. Annoyance ratings were o...
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In a study conducted in the vicinity of Salt Lake City International Airport, community residents reported their annoyance with individual aircraft flyovers during rating sessions conducted in their homes. Annoyance ratings were obtained at different times of the day. Aircraft noise levels were measured, and other characteristics of the aircraft were noted by trained observers. Metrics commonly used for assessing aircraft noise were compared, but none performed significantly better than A-weighted sound pressure level. A significant difference was found between the ratings of commercial jet aircraft and general aviation propeller aircraft, with the latter being judged less annoying. After the effects of noise level were accounted for, no significant differences were found between the ratings of landings and takeoffs. Aircraft noise annoyance reactions are stronger in lowered ambient noise conditions. This is consistent with the theory that reduced nighttime and evening ambient levels could create different reactions at different times of day. After controlling for ambient noise in a multiple regression analysis, no significant differences were found between the ratings of single events obtained during the three time periods: morning, afternoon, and evenings.
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摘要 :
In a study conducted in the vicinity of Salt Lake City International Airport, community residents reported their annoyance with individual aircraft flyovers during rating sessions conducted in their homes. Annoyance ratings were o...
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In a study conducted in the vicinity of Salt Lake City International Airport, community residents reported their annoyance with individual aircraft flyovers during rating sessions conducted in their homes. Annoyance ratings were obtained at different times of the day. Aircraft noise levels were measured, and other characteristics of the aircraft were noted by trained observers. Metrics commonly used for assessing aircraft noise were compared, but none performed significantly better than A-weighted sound pressure level. A significant difference was found between the ratings of commercial jet aircraft and general aviation propeller aircraft, with the latter being judged less annoying. After the effects of noise level were accounted for, no significant differences were found between the ratings of landings and takeoffs. Aircraft noise annoyance reactions are stronger in lowered ambient noise conditions. This is consistent with the theory that reduced nighttime and evening ambient levels could create different reactions at different times of day. After controlling for ambient noise in a multiple regression analysis, no significant differences were found between the ratings of single events obtained during the three time periods: morning, afternoon, and evenings.
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Subsonic and supersonic aircraft concepts proposed through NASA s Fundamental Aeronautics Program have multiple engines mounted near one another. Engine configurations with multiple jets introduce an asymmetry to the azimuthal dir...
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Subsonic and supersonic aircraft concepts proposed through NASA s Fundamental Aeronautics Program have multiple engines mounted near one another. Engine configurations with multiple jets introduce an asymmetry to the azimuthal directivity of the jet noise. Current system noise predictions add the jet noise from each jet incoherently, therefore, twin jets are estimated by adding 3 EPNdB to the far-field noise radiated from a single jet. Twin jet effects have the ability to increase or decrease the radiated noise to different azimuthal observation locations. Experiments have shown that twin jet effects are reduced with forward flight and increasing spacings. The current experiment investigates the impact of spacing, and flight effects on airport noise for twin jets. Estimating the jet noise radiated from twin jets as that of a single jet plus 3 EPNdB may be sufficient for horizontal twin jets with an s/d of 4.4 and 5.5, where s is the center-to-center spacing and d is the jet diameter. However, up to a 3 EPNdB error could be present for jet spacings with an s/d of 2.6 and 3.2.
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Noise reduction inside the cabin of a business jet is one of the most important requirements for public acceptance of the aircraft. A useful approach in this situation of limited experimental data is to try to find some correlatio...
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Noise reduction inside the cabin of a business jet is one of the most important requirements for public acceptance of the aircraft. A useful approach in this situation of limited experimental data is to try to find some correlation between the experimental conditions and measured values of noise. In case of strong correlation it is possible to predict values of a particular noise characteristic of interest for experimental conditions varied in a wide range. This work presents a simple empirical method of prediction of OASPL values and one-third octave band spectrum values. The method is based on correlation between OASPL (or one-third octave band SPL) values and the conditions of the test flight.
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Current empirical models of several turbojet acoustic sources were incorporated in a scheme for prediction of conventional or STOVL jet aircraft noise. The acoustic sources modeled were jet mixing noise, core noise, and broadband ...
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Current empirical models of several turbojet acoustic sources were incorporated in a scheme for prediction of conventional or STOVL jet aircraft noise. The acoustic sources modeled were jet mixing noise, core noise, and broadband shock noise. The free-jet noise was then coupled with a new empirical equation for ground interaction noise generated by a vertically impinging jet. The modification of out-of-ground free-jet acoustic directivity pattern by a Harrier type nozzle installation was incorporated in the prediction of STOVL noise. The jet/ground interaction noise prediction is the result of a flight test of the NASA Ames Harrier jet aircraft that was operated in vertical takeoff and landing. Acoustic data measured with an array of ground level microphones showed ground amplification of jet noise that peaked at a jet height equal to 18 nozzle diameters. At jet heights below 18 nozzle diameters, far-field ground level noise decreased. It is suggested that the noise decrease was caused by refraction of sound upward by the jet ground sheet near-field noise on the airframe was not measured, but published near-field data are examined. Unlike numerous small-scale studies of jet impingement on a hard surface, no tones were found in the Harrier spectra. Implications for improved laboratory simulations of jet/ground interactions are discussed. The acoustic prediction method described gives fairly good agreement with measured far-field noise of the Harrier aircraft during hover in and out of ground effect.
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An analysis is made of the noise reduction potential for the business jet aircraft fleet registered in the United States as of 1975. Noise characteristics of each aircraft are defined at various thrust levels and noise reductions ...
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An analysis is made of the noise reduction potential for the business jet aircraft fleet registered in the United States as of 1975. Noise characteristics of each aircraft are defined at various thrust levels and noise reductions achievable for different design options are determined. Costs and performance penalties are assessed for each option in order to evaluate the consequences of lowering present FAR 36 Appendix C noise levels. With current technology, the exhaust noise of all engines can be reduced significantly with multi-element nozzles, but the addition of a lined ejector provides little additional noise reduction at greatly increased weight and performance penalties. Acoustic liners in exhaust ducts reduce fan or core noise for some engines but inlet liners have little value. Equipping aircraft with new engines achieves major noise reductions but is technically and economically reasonable for only about twenty percent of existing business jet aircraft. To assess noise reductions, a single number criterion is proposed, based on the effective perceived noise level contour that circumscribes a two square-mile area. Also it is recommended that takeoff noise be measured at 2.5 nautical miles from brake release.
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The aim is to provide an up-to-date account and authoritative appraisal of aerodynamic noise concepts, theory and experiments. Particular emphasis is given to practical methods for the prediction, measurement and reduction externa...
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The aim is to provide an up-to-date account and authoritative appraisal of aerodynamic noise concepts, theory and experiments. Particular emphasis is given to practical methods for the prediction, measurement and reduction external noise from jet/fan aircraft. Following a brief overview of relevant aircraft design and operational considerations, the main lectures include detailed presentations on the fundamental theory of aerodynamic noise generation and propagation, basic aero-acoustics of jet efflux noise, engine exhaust noise characteristics, fan noise, airframe self-noise, airframe/engine interaction effects, aero-acoustic measurement and analysis techniques, aircraft flyover noise measurement, noise-source identification and location methods, and ground-based facilities with forward-speed representation. A bibliography of 171 items is included in the publication. (Author)
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The objectives of this study were to develop a rational evaluation of the courses of action and costs to alleviate noise exposure in the vicinity of airports,taking into consideration reduction of aircraft noise at the source,the ...
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The objectives of this study were to develop a rational evaluation of the courses of action and costs to alleviate noise exposure in the vicinity of airports,taking into consideration reduction of aircraft noise at the source,the use of various aircraft operational procedures and various means for achieving noise compatible land use. It is estimated that 90% of the national population exposed to noise impacts of NEF 40or greater reside in the vicinity of 23airports. This project utilizes a subset of 12of these airports as a base to assess the effects of noise control of existing aircraft,new technology aircraft,flight operational variations,and land use conversion on the capital,social,and political costs for achieving a sensible balance between an acceptable noise environment and an expanded air transportation system. (Author)
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This report presents results of an estimate of the national exposure to aircarrier aircraft noise through the year 2000. The forecast was carried out to show the effect of two types of noise abatement options. The first consisted ...
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This report presents results of an estimate of the national exposure to aircarrier aircraft noise through the year 2000. The forecast was carried out to show the effect of two types of noise abatement options. The first consisted of modifications to FAR Part 36 proposed to the Federal Aviation Administration (Notice 76-22) by the U.S. Environmental Protection Agency which would establish lower noise limits for newly designed aircraft in the years 1980 and 1985. The second type consisted of alternative power cutback procedures (FAA AC 91-39 and two variations of ALPA/Northwest Airlines procedure) coupled with minor variations on approach procedures.
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摘要 :
This report presents results of an estimate of the national exposure to aircarrier aircraft noise through the year 2000. The forecast was carried out to show the effect of two types of noise abatement options. The first consisted ...
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This report presents results of an estimate of the national exposure to aircarrier aircraft noise through the year 2000. The forecast was carried out to show the effect of two types of noise abatement options. The first consisted of modifications to FAR Part 36 proposed to the Federal Aviation Administration (Notice 76-22) by the U.S. Environmental Protection Agency which would establish lower noise limits for newly designed aircraft in the years 1980 and 1985. The second type consisted of alternative power cutback procedures (FAA AC 91-39 and two variations of ALPA/Northwest Airlines procedure) coupled with minor variations on approach procedures.
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