Flap Noise

随着预计的航空运输需求到2020年将使世界飞机机队翻一番，降低每架飞机的噪音水平的任务变得极其紧迫。在过去的20年里，由于采用了先进的风扇设计和使用了具有超高旁路比的喷气发动机，仅在降低叶轮机械噪声方面就取得了重大的技术进步。由于这些进步，机身噪声和发动机安装效应引起的非传统噪声源正成为飞机噪声总体降低的主要限制因素。反过来，襟翼噪声是机身进场噪声的一个非常重要的组成部分，最近的一项实验研究表明，襟翼与喷气式飞机的相互作用也可以在起飞条件下产生非常显著的噪声。这使许多传统飞机的生存能力岌岌可危，特别是那些机翼下发动机配置的飞机。与此同时，正如国际气声界所承认的那样，襟翼噪声的机理仍然知之甚少。在新项目中，我们将开发一种新的物理上有洞察力的方法来理解和预测宽带和音调襟翼噪声。在这项工作中，我们将结合和扩展在前两个EPSRC资助的气动声学项目框架下开发的两个模型，形成一个新的统一的噪声预测方案。该方案将捕捉高升力装置的音调和宽带噪声分量，如翼襟翼和襟翼以及它们与湍流射流的相互作用。新模型将在计算流体动力学(CFD)工具预测的声源和使用混合数学建模工具的远场传播之间进行精确匹配。利用新的模型，我们将系统地研究襟翼噪声的机理，并研究控制装置对噪声的影响，如多孔襟翼边缘表面和安装在襟翼后缘的涡流发生器。该项目是先进的数值模拟、高性能计算和最先进的声学分析方法的完美结合。所有研究人员都是各自领域的专家--空气声学、空气动力学、湍流建模和数值方法。因此，这项计划的优点是其跨专业和协作性质，确保各构思和方法互相配合和互相交流。计划中的工作对环境有重大意义，旨在直接改善机场附近居民的生活质素。它还具有商业重要性，可能会保护英国在高科技领域的就业机会，其结果将对空客和罗尔斯-罗伊斯等英国领先的空域行业产生兴趣。这是因为将为声学设计创造更好的物理理解和有价值的预测技术。这些最终应该会导致更环保的飞机，从而在商业上更具竞争力，能够更快地以更低的成本投放市场。这项研究将通过在影响较大的期刊上发表的出版物和在重要国际会议上发表的报告来传播。该项目的国际合作背景加强了潜在的传播途径。项目结果还将通过其他专家会议传播，例如在皇家学会会议上。此外，还将安排一系列研讨会讲座，以进一步在欧洲领先的空气声学中心传播项目成果。该项目的国际合作背景将加强潜在的传播途径。还预计项目中产生的新的训练有素的计算流体动力学家/空气动力学家/空气声学家将在她/他的进一步工作中传播项目后成果。

With the projected demand for air transport set to double the world aircraft fleet by 2020, the task of reducing noise levels of each individual aircraft is becoming extremely urgent. Significant technological advances in the reduction of turbomachinery noise alone has been achieved over the last 20 years due to the implementation of advanced fan designs and the use of jet engines with ultra high bypass ratios. Because of these advances, airframe noise and non-traditional noise sources due to the engine installation effects are becoming a major limiting factor in the overall reduction of the aircraft noise. In turn, flap noise is a very important component of airframe noise for approach conditions and, as a recent experimental study demonstrated, the flap interaction with the jet can also produce very significant noise for take-off conditions. This puts the viability of many conventional aircraft, especially those with the engine-under-the-wing configuration, in jeopardy. At the same time, as recognised by the international aeroacoustic community, the mechanisms of flap noise still remain very poorly understood. In the new project, we will develop a new physically insightful method for understanding and predicting both broadband and tonal flap noise. In this work we will combine and extend the two models developed in the framework of two previous successful EPSRC-funded aeroacoustic projects into a new unified noise prediction scheme. This scheme will capture both the tonal and broadband noise components of the high-lift devices, such as wing flaps and flaperons and their interaction with the turbulent jet. The new model will have an exact match between the sound sources predicted by Computational Fluid Dynamics (CFD) tools and far-field propagation using a mixture of mathematical modelling tools. Using the new model we will systematically study the mechanisms of flap noise and investigate the effect of control devices, such as porous flap edge surfaces and vortex generators installed on the flap trailing edge, on noise.This Project is a well-balanced combination of advanced numerical modelling, high performance computing and state-of-the art acoustic analysis methods. All investigators are experts in their fields - aeroacoustics, aerodynamics, turbulence modelling and numerical methods. Thus a strong side of the Project is its multi-disciplinary and collaborative nature that ensures synergy and cross-fertilisation of ideas and methods.The planned work has great environmental importance, aimed directly at improving the quality of people's lives in the vicinity of airports. It also has commercial importance, potentially safeguarding UK jobs in a high technology area, and its results will be of interest for the leading UK airspace industry such as Airbus and Rolls-Royce plc. This is because greater physical understanding and valuable predictive technology for acoustics design will be created. These should ultimately result in more environmentally friendly, and hence commercially competitive, aircraft that can be brought to the market more quickly and at lower cost. The research will be disseminated via publications in high-impact journals and presentations at key international conferences. The international collaborative context of this project enhances the potential dissemination paths. The projects results will be also disseminated through other specialist meetings, such as at Royal Society Meetings. In addition, a series of seminar talks will be arranged for to further disseminate the projects results in leading European aeroacoustics centres. The international collaborative context of this project will enhance the potential dissemination paths. It is also expected that the new highly trained computational fluid dynamicist/aerodynamicist/aeroacoustician produced in the project will be disseminating the post-project results in her/his further work.