Numerical optimization of porous surfaces to reduce trailing-edge noise

多孔表面的数值优化以减少后缘噪声

• 批准号: 209951091
• 负责人: Professor Dr. Nicolas R. Gauger
• 金额: --
• 依托单位: Lehrstuhl für Strömungslehre und Aerodynamisches Institut (AIA)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/209951091?language=en
• 关键词: Numerical; optimization; porous; surfaces; reduce

At landing approach, airframe noise is one of the major contributors to the overall noise level. Since trailing-edge noise defines an essential part of airframe noise, it is necessary to lower it, to reduce the environmental impact of aircraft noise emissions on the population near airports. In this project, a passive noise reduction technology for trailing-edge noise, i.e., porous surfaces applied to generic trailing edges, is investigated by a hybrid large-eddy simulation/computational aeroacoustics (LES/CAA) approach.In the first phase, the impact of porous surfaces to reduce tonal trailing-edge noise has been analyzed. The computations for various trailing-edge shapes and porous structures have shown to reduce the correlation of the turbulent eddies and to lower the overall sound pressure level by 11dB. The tonal noise has been lowered by an additional 4dB for a porosity having been optimized by a newly developed adjoint formulation of the LES/CAA aproach.In the second phase, the investigation will be extended to broadband noise reduction. The novelty of this analysis is defined by a spanwise variation of the shape of the porous surface, i.e., a sawtooth shape is considered, and an alteration of the porous structure in the streamwise and spanwise direction. Based on a high-fidelity surrogate optimization model, the shape and the structure of the porous surface are optimized. Furthermore, the impact of the angle-of-attack on the noise reduction gain is taken into account and the influence of higher Mach numbers on the acoustic gain at the trailing edge, i.e., on the acoustic perturbations and their effect on the overall aerodynamics, is investigated.In brief, it is the overall objective of this project to analyze the impact of porosity on broadband trailing-edge noise and to reduce it.

在着陆进场时，机体噪声是总噪声级的主要贡献者之一。由于后缘噪声是机体噪声的重要组成部分，因此有必要降低后缘噪声，以减少飞机噪声排放对机场附近居民的环境影响。本项目采用了一种针对后缘噪声的被动降噪技术，本文采用大涡模拟/计算气动声学（LES/CAA）混合方法研究了多孔表面在一般后缘上的应用，第一阶段分析了多孔表面对后缘音调噪声的影响。各种后缘形状和多孔结构的计算表明，减少湍流涡流的相关性，并降低总声压级11分贝。用新开发的LES/CAA方法的伴随公式优化孔隙度，使音调噪声降低了4dB。在第二阶段，研究将扩展到宽带降噪。这种分析的新奇是由多孔表面形状的展向变化来定义的，即，考虑了一种流线型，以及沿流向和展向多孔结构的变化。基于高保真度的代理优化模型，对多孔表面的形状和结构进行了优化。此外，还考虑了迎角对降噪增益的影响，以及较高马赫数对后缘声学增益的影响，即，的声学扰动及其对整体空气动力学的影响，简而言之，这是本项目的总体目标，分析的宽带后缘噪声的孔隙度的影响，并降低它。