Maggi-Rubinowicz Diffraction Correction for Ray-Tracing Calculations of Engine Noise Shielding

Lummer, Markus

doi:10.2514/6.2008-3050

Cited by 45 publications

(30 citation statements)

References 6 publications

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“…The empirical database of the original Heidmann model has been modified in order to reflect more recent developments in the field of engine fan design. Possible shielding effects of the engine fan noise are considered using the DLR ray-tracing tool SHADOW [28]. The application of SHADOW allows to study promising low noise aircraft concepts with significantly reduced fan noise contribution.…”

Section: Noise Assessment Of a Single Aircraft (Level 2)mentioning

confidence: 99%

Aircraft Noise Assessment—From Single Components to Large Scenarios

Delfs¹,

Bertsch²,

Zellmann

et al. 2018

Energies

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Abstract:The strategic European paper "Flightpath 2050" claims dramatic reductions of noise for aviation transport scenarios in 2050: ". . . The perceived noise emission of flying aircraft is reduced by 65%. These are relative to the capabilities of typical new aircraft in 2000. . . ". There is a consensus among experts that these far reaching objectives cannot be accomplished by application of noise reduction technologies at the level of aircraft components only. Comparably drastic claims simultaneously expressed in Flightpath 2050 for carbon dioxide and NOX reduction underline the need for step changes in aircraft technologies and aircraft configurations. New aircraft concepts with entirely different propulsion concepts will emerge, including unconventional power supplies from renewable energy sources, ranging from electric over hybrid to synthetic fuels. Given this foreseen revolution in aircraft technology the question arises, how the noise impact of these new aircraft may be assessed. Within the present contribution, a multi-level, multi-fidelity approach is proposed which enables aircraft noise assessment. It is composed by coupling noise prediction methods at three different levels of detail. On the first level, high fidelity methods for predicting the aeroacoustic behavior of aircraft components (and installations) are required since in the early stages of the development of innovative noise reduction technology test data is not available. The results are transferred to the second level, where radiation patterns of entire conventional and future aircraft concepts are assembled and noise emissions for single aircraft are computed. In the third level, large scale scenarios with many aircraft are considered to accurately predict the noise exposure for receivers on the ground. It is shown that reasonable predictions of the ground noise exposure level may be obtained. Furthermore, even though simplifications and omissions are introduced, it is shown that the method is capable of transferring all relevant physical aspects through the levels.

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Section: Noise Assessment Of a Single Aircraft (Level 2)mentioning

confidence: 99%

Aircraft Noise Assessment—From Single Components to Large Scenarios

Delfs¹,

Bertsch²,

Zellmann

et al. 2018

Energies

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“…Usually these methods based on solution Kirchhoff integral equation (BEM) or on Rubinowicz diffraction approximation. [19][20][21] In the present work we investigate the Geometrical Theory of Diffraction (GTD) 6,12-14 as a tool for approximate determining Green function at shielding effect calculation for noncompact sources (Uniform Theory of Diffraction (UTD) is the improvement version of GTD for obtaining continuous solutions 13 ). GTD approximation represents wave propagation through local characteristics of field like geometrical optics.…”

Section: Diffraction Calculation Methods Comparisonmentioning

confidence: 99%

Airframe Shielding of Noncompact Aviation Noise Sources: Theory and Experiment

Ostrikov¹,

Denisov²

2015

21st AIAA/CEAS Aeroacoustics Conference

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In the present work we investigate the effect of noncompactness of aviation noise sources on airframe shielding. Performed experimental results showed what shielding effect is very sensitive to the type of source and geometrical features of the shielding surface. For example, the features of rotor tonal noise and rotor broadband noise shielding are differed. In the present work we seek for the theoretical methods for correct predicting of shielding effect for noncompact sources, Fresnel/Kirchhoff methods and Geometry Theory of Diffraction (GTD) are under consideration together with some exact solutions. GTD shows the optimal results as compared with other theories for calculating shielding efficiency in the case of noncompact sources calculation. If GTD is applied to shielding effect for noncompact sources generating rotating azimuthal modes (fan tonal noise), then some interesting features are appeared such as the loss of symmetry, the strong dependence of shielding field on the number of azimuthal mode, existence of directions, in which sound emission is considerably amplified.

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“…The first tool was the Parametric Aircraft Noise Analysis Module (PANAM), described by Bertsch (2013), which is used to perform the noise prediction of the engines. The second tool was SHADOW and further explained by Lummer (2008). It is used to consider the shielding of the sound generated by the fan.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of ultra-high bypass ratio engines for an over-wing aircraft configuration

Giesecke

Lehmler

Friedrichs

et al. 2018

J. Glob. Power Propuls. Soc.

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Today, main hub airports are already at their capacity limit and hence, smaller airports have become more interesting for providing point-to-point connections. Unfortunately, the use of regional airports induces an increased environmental footprint for the population living around it. In an attempt to solve the related problems, the research project Coordinated Research Centre 880 aims to examine the fundamentals of a single-aisle aircraft with active high-lift configuration powered by two geared ultra-high bypass turbofan engines mounted over the wing. Low direct operating costs, noise shielding due to the over-wing configuration, and short runway lengths are the main advantages. Highlighting the performance, economical and noise benefits of a geared ultra-high bypass engine is the key aim of this paper. This assessment includes a correspondingly adjusted aircraft. Open literature values are applied to design the two investigated bypass ratios; a reference engine with a bypass ratio of 5 and 17 respectively. This study shows that a careful selection of engine mass flow, turbine entry temperature and overall pressure ratio determines the desirable bypass ratio. The aircraft direct operating costs drop by 5.7% when comparing the designed conventional with a future ultra-high bypass ratio engine. Furthermore, the sound at source for a selected mission and operating condition can be reduced by 7 dB. A variable bypass nozzle area for the ultra-high bypass ratio engine is analysed in terms of performance and operability. An increase of safety margin is shown for the turbofan engine with a variable bypass nozzle. It is concluded that this unconventional aircraft configuration with ultra-high bypass ratio engines mounted over the wing has the potential to relieve main hub airports and reduce the environmental impact.

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Maggi-Rubinowicz Diffraction Correction for Ray-Tracing Calculations of Engine Noise Shielding

Cited by 45 publications

References 6 publications

Aircraft Noise Assessment—From Single Components to Large Scenarios

Aircraft Noise Assessment—From Single Components to Large Scenarios

Airframe Shielding of Noncompact Aviation Noise Sources: Theory and Experiment

Evaluation of ultra-high bypass ratio engines for an over-wing aircraft configuration

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