Application of an Aircraft Design-To-Noise Simulation Process

25th AIAA/CEAS Aeroacoustics Conference

Thomas

Sanders³

et al. 2019

Self Cite

The Aircraft Noise Working Group (ANSWr) was established by DLR, ONERA, and NASA to compare simulation tools, establish guidelines for noise prediction, and to assess uncertainties associated with the simulation. To accomplish these goals, a benchmark problem was initiated by the group. The setup is documented and initial results for the reference aircraft are discussed. The reference aircraft is a conventional tube-andwing configuration with the engines installed under the wings. The aircraft noise simulations are performed for departure and approach conditions, and the results obtained with three different system noise prediction tools are compared. At the aircraft level, the overall agreement is good between the three predictions. Peak noise levels agree within 3-4 dB. Fan and jet component predictions are generally very similar although there can be differences of up to 7 dB in some fan tone levels. The prediction of airframe components shows the most disagreement between the three methods with some differences of 6 dB for the major components and greater differences at high frequencies. There can also be differences in the frequency of the peak level and in the rank order of the airframe components. At the total airframe noise level, the differences are reduced to no more than 3-4 dB. While there is general agreement in shape characteristics of predicted ground noise isocontours, the differences between the three methods can result in more significant disagreement in the sizes of the isocontours.

Section: Discussionmentioning

confidence: 99%

“…• conceptual aircraft design; see Refs. 6,28,30 • flight procedure; see Refs. 6,28,31 • high-quality engine design & performance; see Ref.…”

Section: Benchmark Setupmentioning

confidence: 99%

The Aircraft Noise Simulation Working Group (ANSWr) - Tool Benchmark and Reference Aircraft Results

25th AIAA/CEAS Aeroacoustics Conference

Thomas

Sanders³

et al. 2019

Self Cite

“…As a consequence, the parameters which refer to the operational and geometrical data can be optimized for minimal noise contribution (within predefined limits). This tool is mainly used to assess the impact of lownoise modifications to individual components on-board of existing aircraft or for the design of new low-noise aircraft [29].…”

Section: Comparison With Aircraft System Noise Predictionmentioning

confidence: 99%

Analysis of landing gear noise during approach

Martinez

22nd AIAA/CEAS Aeroacoustics Conference

Simons

et al. 2016

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Airframe noise is becoming increasingly important during approach, even reaching higher noise levels than the engines in some cases. More people are affected due to low flight altitudes and fixed traffic routing associated with typical approaches. For most aircraft types, the landing gear system is a dominant airframe noise source. However, this element can only be modeled in an approximate manner in wind tunnel experiments. In this research, flyovers of landing aircraft were recorded using a 32 microphone array.Functional beamforming was applied to analyze the noise emissions from the landing gear system. It was confirmed that for some aircraft types, such as the Airbus A320 and the Fokker 70, the nose landing gear is a dominant noise source during approach. The correlation between the noise levels generated by the landing gear and the aircraft velocity was found to be significant, explaining about 70% of the variability found in the noise levels, which is in good agreement with all known theory. Moreover, the experimental results for the Airbus A320 measurements were compared with those obtained using the DLR system noise prediction tool PANAM. Whereas the total aircraft noise levels were in good agreement, the measurements indicate a higher contribution from the nose landing gear noise compared to the predictions.

“…After a successful run of the PANAM module, the resulting noise levels and areas are then fed back into the PrADO simulation process for an overall assessment or an entire low-noise design study. This overall design-to-noise process and another application case with the focus on engine noise shielding are described in more detail in an accompagning paper 21 .…”

Section: Transposition To Flight -Community Noise Assessmementmentioning

confidence: 99%

“…[21] ) has been updated for an application within the SLED project. PrADO has been modified in order to directly input and process experimental data or results from high-fidelity computation.…”

Section: Transposition To Flight -Community Noise Assessmementmentioning

confidence: 99%

Aerodynamic and Acoustic Design of Silent Leading Edge Device

Pott-Pollenske

Wild

20th AIAA/CEAS Aeroacoustics Conference

2014

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The high lift system noise of current transport aircraft is dominated by slat noise under certain operating conditions. Suitable means to reduce the noise impact in the vicinity of airports are (i) to increase the distance between the source and the observer and (ii) to reduce source noise levels. Both objectives can only be achieved by means of a multidisciplinary aerodynamic and acoustic development since the slat is at the same time a very important element to achieve the necessary high lift performance and the dominant noise source of a high lift system 1 . First attempts to reduce slat noise by means of a slat setting optimization were conducted at DLR in the mainframe of the project Leiser Flugverkehr 2 . This purely acoustically driven study revealed that a slat gap reduction results in a local flow speed decrease at the slat trailing edge and thus to remarkable noise reductions of up to 10 dB, the latter of course depending on the magnitude of the slat gap reduction. The drawback of this approach was that at the same time the aerodynamic performance of the high lift system was degraded by a non-acceptable level. However, this study was the starting point of the DLR project LEISA (Low noise exposing integrated design for start and approach) that combined activities in the research areas of high lift system design and aero-acoustic design, which were carried out rather independently up to this point in time. In the project LEISA different types of high lift configurations were addressed and investigated in a 2-dimensional approach. The first one is a long chord slat that provided a source noise reduction of about 6 dB while maintaining the aerodynamic performance of the reference slat system. The second, and more radical concept was to omit the slat and apply a droop nose system in order to reduce the aerodynamic losses as much as possible. The finally achieved source noise reduction with the droop nose system was about 8 dB while from the aerodynamic point of view about 50% of the losses were recovered. Based on these promising results the transposition of these high lift systems to a real 3-dimensional wing was carried out in the follow-up project SLED (Silent Leading Edge Devices). The final outcome of the project SLED can be summarized as follows. From the aerodynamic point of view the performance of the 3-dimensional long chord slat compares very well to the reference slat system. The final droop nose design was capable to recover about 40% of the lift loss due the omitted slat. The final acoustic results in terms of source noise levels are an overall 4 dB noise reduction for the long chord slat and about 6 dB noise reduction in case of the droop nose. The obtained aerodynamic and acoustic characteristics were finally transposed to flight in order to assess the effect on community noise which can be expressed in terms of noise isocontour areas. Regarding the 60 dB(A) and the 65 dB(A) noise iso contour areas the achieved benefit is a reduction of up to 40% of the respective area's size. 1 Research Eng.,...