Aircraft Noise Assessment—From Single Components to Large Scenarios

Abstract

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.

10 years of joint research at DLR and TU Braunschweig toward low-noise aircraft design-what did we achieve?

“…It included additional updates and upgrades to the process toward its current status with the focus on noise immission in early 2018, see Refs. [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]…”

“…An initial simulation process of such an overall scenario assessment is defined by a three-staged simulation approach, i.e., the component level, the single aircraft level, and the system scenario level as described in Ref. 38 The single aircraft level is thereby comprised of the entire simulation process of the DLR and TU BS cooperation as depicted in Ref. 3 The individual technologies and components are provided from the component level (based on their high-fidelity simulation results), transferred to the single aircraft level (here the technologies and components are installed on an aircraft and the overall noise immission is predicted), to finally integrate the new vehicles into a scenario (the overall noise immission around the airport is predicted according to the scenario, see Ref.…”

“…As a final step, the initial results of this new process still have to be subject to an uncertainty assessment as described previously. At the time of the initial application as described in Ref, 38 the uncertainty assessment had still been under development.…”

Predicting Far-Field Noise Generated by a Landing Gear Using Multiple Two-Dimensional Simulations

“…To fulfill high design standards, new aircraft designs demand efficient AFN prediction techniques to assess the noise impact. Thus, multi-fidelity approaches are required to enable efficient and accurate aircraft noise assessment at different design stages [3]. The accuracy of noise prediction techniques is attributed to various factors, including turbulence modelling and/or acoustic analogy implementation and boundary conditions [4][5][6][7][8][9].…”

“…The BANC workshops focus on improving the far-field noise prediction accuracy of the 3D simulations and reducing the computation time. There are a few semi-empirical tools developed to facilitate the noise prediction of the LG during the design stage [3,7]. Among these, the Landing Gear Model and Acoustic Prediction tool (LGMAP) has been developed for a quick noise estimate of the LG [15].…”