Aircraft noise

About: Aircraft noise is a research topic. Over the lifetime, 3051 publications have been published within this topic receiving 32039 citations.

Development of an advanced continuous descent concept based on a 737 simulator

Abstract: It is well known that noise restrictions impact airport approach and departure procedures at many airports worldwide The research described here presents an advanced continuous descent approach (CDA) concept using current and future capabilities of flight management systems (FMS) to allow idle thrust (low noise) descent from about 8000 ft to 2000 ft, yielding significant reductions in aircraft noise on the local airport community The advances in flight management technology described here would allow tailoring of the final descent path to include aircraft type, predicted winds, initial altitude, vehicle weight, time of arrival, and initial/final descent speeds This research is based on a high fidelity simulation of a 737-700 aircraft Conclusions and techniques based on this aircraft would have to be adjusted or re-tuned before they are applied to other aircraft types to correctly match thrust/drag characteristics

Computational AeroAcoustics of a Realistic Co-Axial Engine in Subsonic and Supersonic Take-Off Conditions

Abstract: The present work is devoted to the numerical simulation of acoustic emissions characterizing turbojet engines, a subject that is relevant of the more general purpose of aircraft noise prevision and reduction. More precis ely, we explore here the ability of a structured CAA (Computational AeroAcoustics) method/solver to address complicated problems of engine noise prediction. With that end, and by using the ONERA’s CAA solver sAbrinA.v0 , we conduct realistic calculations of aft fan nois e emission, which involve both a full-3D exhaust geometry (with its pylon / internal bifurcations) and typical fan noise modal contents (high azimuthal order / frequency). The re sults highlight how far the installation / refraction effects induced by the complex geometry / flow of an engine can affect its fan noise emission. Results also tend to demonstrate that bot h the here used CAA method and solver are mature enough to face out industrial-like engin e noise problems.

Assessing the shielding of engine noise by the wings for current aircraft using model predictions and measurements.

Abstract: Reducing aircraft noise is a major issue to be dealt with by the aerospace industry. In addition to lowering noise emissions from the engine and airframe, also the shielding of engine noise by the aircraft is considered as a promising means for reducing the perceived noise on the ground. In literature, noise shielding predictions indicate significant reductions in received noise levels for blended wing body configurations, but also for conventional aircraft with the engines placed above the wings. Little work has been done in assessing these potential shielding effects for full aircraft under real operational conditions. Therefore, in this work, noise shielding for current aircraft is investigated using both measurements and model predictions. The predictions are based on the Kirchhoff integral theory and the Modified Theory of Physical Optics. For the comparison between the predictions and measurements, Twenty Fokker 70 flyovers are considered. The data analysis approach for the extraction of shielding l...

Aircraft noise synthesis system

Abstract: A second-generation Aircraft Noise Synthesis System has been developed to provide test stimuli for studies of community annoyance to aircraft flyover noise. The computer-based system generates realistic, time-varying, audio simulations of aircraft flyover noise at a specified observer location on the ground. The synthesis takes into account the time-varying aircraft position relative to the observer; specified reference spectra consisting of broadband, narrowband, and pure-tone components; directivity patterns; Doppler shift; atmospheric effects; and ground effects. These parameters can be specified and controlled in such a way as to generate stimuli in which certain noise characteristics, such as duration or tonal content, are independently varied, while the remaining characteristics, such as broadband content, are held constant. The system can also generate simulations of the predicted noise characteristics of future aircraft. A description of the synthesis system and a discussion of the algorithms and methods used to generate the simulations are provided. An appendix describing the input data and providing user instructions is also included.

A community survey of helicopter noise annoyance conducted under controlled noise exposure conditions

Abstract: Reactions to low numbers of helicopter noise events (less than 50 per day) were studied in a community setting. Community residents were repeatedly interviewed about daily noise annoyance reactions on days when helicopter noise exposures were, without the residents' knowledge, controlled. The effects of maximum noise level and number of noise events on helicopter noise annoyance are consistent with the principles contained in LEQ-based noise indices. The effect of the duration of noise events is also consistent with LEQ-based indices. After removing the effect of differences in noise levels (LEQ) there is not an important difference between reactions to impulsive and nonimpulsive types of helicopters. EPNL, where corrected for number of overflights, and LEQ are approximately equally successful in representing the characteristics of noise which are related to human response. The new type of design provided estimates of the parameters in a noise reaction model which would not obtained with a similar degree of precision from conventional study designs.