The influence of lamination angles on the interior noise levels of an aircraft

Cover of: The influence of lamination angles on the interior noise levels of an aircraft |

Published by National Aeronautics and Space Administration, Langley Research Center, National Technical Information Service, distributor in Hampton, Va, [Springfield, Va .

Written in English

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Subjects:

  • Aircraft production.,
  • Cylindrical shells.,
  • Equations of motion.,
  • Finite element method.,
  • Frequency ranges.,
  • Thin walled shells.,
  • Structural design criteria.,
  • Noise reduction.,
  • Noise intensity.,
  • Laminates.

Edition Notes

Book details

StatementChristian M. Fernholz, Jay H. Robinson.
SeriesNASA technical memorandum -- 110250.
ContributionsRobinson, Jay H., Langley Research Center.
The Physical Object
FormatMicroform
Pagination1 v.
ID Numbers
Open LibraryOL15498099M

Download The influence of lamination angles on the interior noise levels of an aircraft

Optimization of lamination angle for the reduction of interior noise is performed using a finite element model of an actual aircraft fuselage. The aircraft modeled for this study is the Beech Starship.

Point forces simulate the structure borne noise produced by the engines and are applied to the fuselage at the wing mounting locations. the lamination angles in the fuselage.

Sound pressure level reductions of roughly 4 dB were attained at multiple locations in the passenger cabin. For frequencies outside the optimization range, the acoustic pressure response may increase after optimization.

The effects of changing lamination angle on the overall structural integrity of the. Get this from a library. The influence of lamination angles on the interior noise levels of an aircraft.

[Christian M Fernholz; J H Robinson; Langley Research Center,; United States. National Aeronautics and Space Administration,]. Corpus ID: The Influences of Lamination Angles on the Interior Noise Levels of an Aircraft @inproceedings{FernholzTheIO, title={The Influences of Lamination Angles on the Interior Noise Levels of an Aircraft}, author={Christian M.

Fernholz and J. Robinson}, year={} }. an investigation of the influence of composite lamination angle on the interior noise levels of a beech starship. no abstract provided. supplemental notes: p.

ill.; includes bibliographical references (p. ) proceedings of noise-con vol. poughkeepsie, ny: noise control foundation, corporate authors:Cited by: 3. The A weighted noise level has been adopted by the FAA as the accepted measure to consider aircraft noise.

For noise sources in motion, like aircraft, noise levels can change over time. For example, the sound level of a plane increases as it approaches, and then as it flies away the sound level decreases. The ply angles serve as the design variables in optimization.

The optimal design was obtained after 15 iterations with a 2 dB reduction in the average interior sound pressure level. The ply angle orientation shifted from an initially symmetric lay-up to an unsymmetric lay-up in the final design.

U.S. Department of Transportation Federal Aviation Administration Independence Avenue, SW Washington, DC () tell-FAA (() ). In order to determine whether exposure to aircraft interior noise is a health hazard, sound samples were taken in two types of aircraft: a Cessna and a Piper PA Seminole.

Propeller synchrophasing is an effective way of reducing interior noise and vibration of turboprop-driven aircraft. However, synchrophasing has achieved limited success in practice for the reason that the predetermined phase angles are not acoustically optimized for maximum noise.

Measure the noise levels produced by aircraft landing on and taking off from flight decks of aircraft carriers. Assess these levels in terms of (1) the hearing hazards they present to personnel exposed to them for various periods of time, with varying degrees of ear protection, and (2) the extent to which they degrade speech communication.

tem of the existing aircraft will be replaced by a jet engine for the new aircraft. In a jet-powered aircraft the interior noise level is mainly determined by noise generated by turbulent boundary layers, TBL, if all interior noise sources like ventillation systems, fans, hydrau-lic systems etc have been properly acoustically treated.

The grain in each ply (or layer) is at either or degree angles to adjacent plies, and the plies are bonded with high pressure and temperature using waterproof glue. A thin sheet of aircraft plywood can easily cost more than $ Wood, when applied to aircraft structures, has significant positive.

and negative. characteristics. Sound Level Meter Types and Performance. Sound level meters used by OSHA meet American National Standards Institute (ANSI) Standard S (R) or S, "Specifications for Sound Level Meters." These ANSI standards set performance and accuracy tolerances according to three levels of precision: Types 0, 1, and 2.

A sound level of 0 dB is approximately the threshold of human hearing and is barely audible under extremely quiet listening conditions. Normal speech has a sound level of approximately 60 dB; sound levels above dB begin to be felt inside the human ear as discomfort.

Sound levels between to dB are felt as pain (Berglund and Lindvall. The “Aircraft noise level” is location specific. The maximum levels in Tables C4, C5 and C6 provide an arithmetic average, the minimum and the maximum of the range of aircraft maximum levels recorded for the different aircraft types.

The aircraft maximum levels in Tables C4, C5 and C6 are not “Aircraft noise levels” as defined in AS The current techniques available for predicting interior noise levels are outlined, and the limitations of these techniques, particularly in their application to future high‐speed aircraft, are discussed.

The relative importance of each external noise source is discussed, with special emphasis on the boundary layer, the engines, and the wake. Interaction of the noise sources and the effect. interior noise levels of a small piston-prop aircraft in flight and on the apron, Ivošević et al.

[9, 10, 11 and 12] have shown that at certain flight stages interior noise exceeds dBA. Study of the long-term interior noise impact on per-formance of the helicopter pilots has shown relatively.

A Aircraft sound pressure levels within the 10 dB-down points (see A) must exceed the mean ambient noise levels determined in section A by at least 3 dB in each one-third octave band, or must be adjusted using a method approved by the FAA; one method is described in the current advisory circular for this part.

For example, if eight takeoffs and eight landings occur between 7 a.m. and 10 p.m., they are reflected in the noise exposure level as 16 aircraft operations. If those same eight takeoffs and eight landings all occur between 10 p.m.

and 7 a.m., they are reflected in the noise exposure levels as the equivalent of aircraft operations. Aircraft noise is noise pollution produced by an aircraft or its components, whether on the ground while parked such as auxiliary power units, while taxiing, on run-up from propeller and jet exhaust, during take off, underneath and lateral to departure and arrival paths, over-flying while en route, or during landing.

[citation needed] A moving aircraft including the jet engine or propeller. 29 Ronald Reagan Washington National (DCA) Taxi Measurement Data Aircraft taxiway noise was measured at Ronald Reagan National Airport (DCA) on J and July 3, Sound level meters and a video system were deployed in order to obtain noise levels, aircraft.

random noise. White random noise contains equal energy per hertz and thus has a constant spectral density level. Pink random noise contains equal energy per measurement band and thus has an octave or one-third octave band level which is constant with frequency. Sound Field Definitions (see ISO ) Free field.

average noise exposure level, Lden.5,6 The standard ISO has tables with % HA as a function of L dn and Lden for various transportation noise sources.7 A review by Gelderblom et al.8 confirms these data for aircraft noise. Another review suggests different relationships, particularly for aircraft noise annoyance From the standpoint of marketing as well as safety, control of aircraft interior noise is of considerable interest to the manufacturers of business aircraft.

The interior acoustics engineer in the industry, having no fund of accumulated experience or research to draw from in the industry itself, has to piece together a working design procedure.

The Integrated Noise Model (INM), Version 7, includes the effect of meteorology in two ways (INM Users Guide ). First, temperature is used to calculate aircraft performance; that is, an aircraft climbs much better in cool weather than in hot weather.

INM 7 now includes an option to match atmospheric sound propagation to aircraft performance. Interior sound levels of general aviation aircraft are reviewed and compared with corresponding levels in commercial aircraft, buses, automobiles and passenger trains.

Noise sources are classified into three groups -- propulsion system, external flow and on-board equipment -. The noise levels were expressed as an Effective Perceived Noise Level (EPNdB) and permitted heavier aircraft to make more noise.

[20] The adoption of Part 36 encouraged new airplane types to be markedly quieter than the generation of turbojets developed in the late s and early s.

• Noise limits on the aircraft (requiring mufflers or baffles, or a limit on engine size). Although there is no handy library or compilation of sound data for RC aircraft, my experience shows that the typical sound levels for various types of RC aircraft, at a reference distance of feet, are.

CHAPTER 6 AIRCRAFT NOISE ANALYSIS 6‐2 Spokane International Airport Master Plan (March ) The strength, or loudness, of a sound wave is measured using decibels on a logarithmic scale.

The range of audibility of a human ear is 0 dB (threshold of hearing) to dB (pain begins). Aircraft noise is defined as sound produced by any aircraft on run-up, taxiing, take off, over-flying or landing. Aircraft noise is a significant concern for approximately square kilometers surrounding most major airports.

Aircraft noise is the second largest (after roadway noise) source of environmental noise. aircraft noise than for road traffic or railway noise at the same exposure level.

However, there is evidence that the annoyance response to aircraft noise has even increased over the years, and that exposure-response curves based on older aircraft noise annoyance data may no longer apply.8,9 This stresses the need. As the associated noise limits are higher for larger, heavier aircraft, this figure permits a comparison between the relative performance across a range of different aircraft types.

The data has been reviewed, and new aircraft noise levels that have been certified by EASA during the to. High levels of cockpit noise in an aircraft can damage the hearing of pilots who are exposed to this hazard for many hours.

Cockpit noise in a jet aircraft is mostly due to airflow at hundreds of miles per hour. This 3x3 contingency table shows 61 observations of data collected by an airline pilot using a handheld sound meter in a Boeing $\begingroup$ If reliable sources could be found it would probably be best to rate the aircraft on a standard scale (Sound Pressure Level (SPL) in dB).

This will make it easier to compare to other sound measurements people may come across. $\endgroup$ – voretaq7 Feb 12 '16 at 2 УДК 7. () ББК Authors: Komarov Valeriy A. Borgest Nikolay M. Vislov Igor' P.

Vlasov Nikolay V. Kozlov Dmitriy M. Korolkov Oleg N. Maynskov Vladimir N. The outside of aircraft engines (around dB at takeoff) and conditions on other aircraft may have higher or lower noise levels. Sound insulation also varies among aircraft. What are the recommended levels for noise at work.

We recommend that all worker exposures to noise be controlled below a level equivalent to 85 dBA for eight hours to. The MAC’s Residential Sound Mitigation Program within the federally‐recognized 65 DNL noise contour was very successful in reducing interior noise levels for homes within the most noise‐ impacted areas.

According to homeowner surveys, the program has increased homeowners’. Aircraft noise exerts an adverse influence on the environment and on people's health, and is also a performance issue.

The aircraft noise problem is a complex topic that covers a number of areas, including passenger cabin and cockpit noise, ramp noise, structure‐borne noise, propulsive system noise, jet noise, airframe noise, etc., each of which requires separate modeling and mitigation.

In general,effective noise control include the use of both absorption and barriers for airborne noise and both isolation and damping for structureborne noise.

It is important to remember that sound is mechanical energy, and that it will always find paths to travel from the noise source to the interior of the aircraft. PDF | On May 1,Aliyu Ahmad Aliyu and others published INFLUENCE OF AIRCRAFT NOISE ON RESIDENTIAL PROPERTY VALUES: EVIDENCE FROM CURRENT LITERATURE | Find, read and cite all the research you.Aircraft Noise Characteristics and Metrics A PARTNER Project 24 Report Shashikant Ramdas More PARTNER-COE July This work was conducted under PARTNER Projects 1, 2, and Basic Principles of Ultrasonic Testing.

Ultrasonic Testing (UT) uses high frequency sound energy to conduct examinations and make measurements. Ultrasonic inspection can be used for flaw detection/evaluation, dimensional measurements, material characterization, and more.

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