7,894 research outputs found
Data for 'On the assessment of subjective response to tonal content of contemporary aircraft noise'
No full textDataset for paper "On the assessment of subjective response to tonal content of contemporary aircraft noise" by Antonio J. Torija, Seth Roberts, Robin Woodward, Ian. H. Flindell, Andrew R McKenzie and Rod H. Self published in Applied Acoustics
The file contains data for the acoustics/psychoacoustics characterization of the aircraft sounds tested, and the associated average value of Preference Rating
One page is added per acoustics/psychoacoustics/perceptual parameter.</span
Data for: Airport noise modelling for strategic environmental impact assessment of aviation
No full textData for figures of the paper: Airport noise modelling for strategic environmental impact assessment of aviation.
This paper analyses the applicability and discusses the unavoidable limitations and advantages of existing simplified airport noise models within the context of multi-disciplinary strategic environmental impact assessment of aviation. Simplified airport noise models satisfying the above requirements and developed to be coupled with technology evaluators, e.g. Rapid Aviation Noise Evaluator (RANE) model [Torija et al., 2017], can inform policy decisions about which future technology platforms would be likely to be the most environmental efficient when considered holistically. Based on the specific conditions tested, the straight-out trajectory assumption and the use of generic aircraft types seems valid approximations for computing aviation noise outputs.</span
Aircraft classification for efficient modelling of environmental noise impact of aviation
No full textWith the environmental externalities of civil aviation under unprecedented scrutiny, and with the projected significant increase in air traffic demand over the next few decades, fleet-level studies are required to assess the potential benefit of novel aircraft technologies and operational procedures for minimising environmental impact of aviation. Using a statistical classification process, the UK commercial aircraft fleet is reduced to four representative-in-class aircraft onthe basis of aircraft physical characteristics, and aircraft noise and engine exhaust emissions. These four representative aircraft, that appropriately capture the noise and emissions characteristics for each category within the UK commercial fleet, are also selected to be used as baseline cases for the high-level assessment of the environmental benefit of novel aircraft technologies. For the particular case of aviation noise, the modelling tools are highly sensitiveto the number of aircraft types in the flight schedule. A reduction of about 80% in computational time with relatively minor decrease in accuracy (between -4% and +5%) is observed when the whole aircraft fleet is replaced with the four representative-in-class aircraft for computing noise contours. Therefore, the statistical classification and selection of representative-in-class aircraft presented in this paper is a valid approach for the rapid and accurate computation of a large number of exploratory cases to assess aviation noise reduction strategies
Aeroacoustic catastrophes: upstream cusp beaming in Lilley's equation
No full textThe downstream propagation of high-frequency acoustic waves from a point source in a subsonic jet obeying Lilley's equation is well known to be organized around the so-called ‘cone of silence’, a fold catastrophe across which the amplitude may be modelled uniformly using Airy functions. Here we show that acoustic waves not only unexpectedly propagate upstream, but also are organized at constant distance from the point source around a cusp catastrophe with amplitude modelled locally by the Pearcey function. Furthermore, the cone of silence is revealed to be a cross-section of a swallowtail catastrophe. One consequence of these discoveries is that the peak acoustic field upstream is not only structurally stable but also at a similar level to the known downstream field. The fine structure of the upstream cusp is blurred out by distributions of symmetric acoustic sources, but peak upstream acoustic beaming persists when asymmetries are introduced, from either arrays of discrete point sources or perturbed continuum ring source distributions. These results may pose interesting questions for future novel jet-aircraft engine designs where asymmetric source distributions arise
Airport noise modelling for strategic environmental impact assessment of aviation
No full textAs projected by different agencies the aviation market will experience a significant increase in air traffic demand over the next decades, driven by the large demand of the Asia-Pacific region. To overcome the further deterioration of the quality of life of communities living around airports, the various aviation stakeholders are required to explore scenarios with different technology options, flight procedures, and fleet replacement strategies. Of course, the assessment of aviation scenarios must be addressed in a more integrated manner than hitherto,where noise, air quality and carbon release are considered. For such purpose, simplified airport noise models are required to overcome the important input data requirements and computation complexity of detailed airport noise models, and also to ensure compatibility against other environmental and economic models. This paper analyses the applicability and discusses the unavoidable limitations and advantages of existing simplified airport noise models within thecontext of multi-disciplinary strategic environmental impact assessment of aviation. Simplified airport noise models satisfying the above requirements and developed to be coupled with technology evaluators, e.g. Rapid Aviation Noise Evaluator (RANE) model [Torija et al., 2017], can inform policy decisions about which future technology platforms would be likely to be the most environmental efficient when considered holistically. Based on the specific conditions tested, the straight-out trajectory assumption and the use of generic aircraft types seems valid approximations for computing aviation noise outputs
Self-archiving practice and the influence of publisher policies in the social sciences
No full textAuthors in different disciplines exhibit very different behaviours on the so-called ‘green’ road to open access, i.e. self-archiving. This study looks at the self-archiving behaviour of authors publishing in leading journals in six social science disciplines. It tests the hypothesis that authors are self-archiving according to the norms of their respective disciplines rather than following self-archiving policies of publishers, and that, as a result, they are self-archiving significant numbers of publisher PDF versions. It finds significant levels of
self-archiving, as well as significant self-archiving of
the publisher PDF version, in all the disciplines
investigated. Publishers’ self-archiving policies have
no influence on author self-archiving practice
Aerodynamics and aeroacoustics investigation of a low speed subsonic jet
No full textLow and high speed subsonic jets have been studied in the last 50 years mainly due its large application in industry, such as the discharge of turbojets and turbofan engines. The purpose of this work is to investigate the aerodynamics and the acoustic noise generated by a single stream jet flow operating at low Mach number 0.25 and Reynolds number of 2,1 105. The main focus is the flow and acoustics characterization of this low speed jet by appling different experimental techniques for evaluating the velocity field via measurements with pitot tube and hot-wire anemometry and farfield noise acquisition by free field microphones. In order to verify the validity of aeroacoustics prediction for such low speed jet, a Computational Fluid Dynamics by means of RANS simulations via k- SST model have been employed coupled with a statistically low-cost Lighthill-Ray-Tracing method in order to numerically predict the acoustic noise spectrum. Sound pressure level as a function of frequency is contructed from the experiments and compared with the noise calculations from the acoustic modeling. The numerical results for the acoustic and flow fields were well compared with the experimental data, showing that this low-cost flow-acoustic methodology can be used to predict acoustic noise of subsonic jet flows, even at low speeds
Framework for predicting Noise-Power-Distance curves for novel aircraft designs
No full textAlong with flight profiles, Noise-Power-Distance (NPD) curves are the key input variable for computing noise exposure contour maps around airports. With the development of novel aircraft designs (incorporating noise reduction technologies) and new noise abatement procedures, NPD datasets will be required for assessing their potential benefit in terms of noise reduction around airports. NPD curves are derived from aircraft flyover noise measurements taken for a range of aircraft configurations and engine power settings. Clearly then, empirical NPD curves will be unavailable for novel aircraft designs and novel operations. This paper presents a generic framework for computationally generating NPD curves for novel aircraft and situations. The new framework derives computationally the NPD noise levels that are normally derived experimentally, by estimating noise level variations arising from technological and operational changes with respect to a baseline scenario, where the noise levels are known, or otherwise estimated. The framework is independent of specific prediction methods and can use any potential new model for existing or new noise sources. The paper demonstrates the methodology of the framework, discusses its benefits and illustrates its applicability by deriving NPD curves for an unconventional approach operation and for a future concept blended-wing-body (BWB) aircraft
Closed-form analytical approach for calculating noise contours of directive aircraft noise sources
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