LFC-UK: Development of Underpinning Technology for Laminar Flow Control

世界石油供应正在迅速减少，在未来的10年或20年里，每桶石油的价格将无情地螺旋式上升。航空是一个重要的石油消费者，也牵连到全球变暖，因为它产生大量的二氧化碳和氮氧化物。随着机场的扩建，飞机噪音问题日益严重。由于这些原因，我们现在所知道的航空将很快变得无法生存。这个问题没有单一的解决方案，发动机、机身设计、调度以及人们对无限航空旅行的期望的巨大变化是不可避免的。在这里，我们解决了最重要的问题之一，改进空气动力学，并开发了层流控制（LFC）的基础技术，即飞机上的减阻技术。这将成为飞机设计的基石。即使是10%左右的阻力节约，也会转化为燃料成本的巨大节约和大气污染的巨大减少。该技术在军用飞机上的应用，其中航程通常是主要要求，船舶应用同样重要。发展可行的LFC设计需要复杂的数学、计算和实验研究，以开始过渡到湍流及其控制。现有的工具过于粗糙，无法发挥作用，并且很少包含流体物理的输入。需要克服的主要障碍是：a)在存在表面缺陷、弯曲、降雨的混乱大气中，我们如何指定流过机翼的一般输入干扰？昆虫和许多其他复杂的特征b)我们如何解决与复杂的3D流动中线性和非线性扰动增长相关的数学问题c)我们如何找到一个基于流动物理学的过渡开始标准，该标准足够准确，以避免与现有LFC策略相关的大规模过度设计，同时又足够有效，可用于设计办公室)我们如何使用实验室中的实验来预测飞行实验中会发生什么？我们如何才能设计出足够强大的控制策略，用于民用飞机？我们如何量化制造公差，例如维持层流所需的表面波浪度或颠簸？上述挑战是巨大的，只能通过基于数学，计算和实验卓越的创新研究来克服，就像我们组建的团队一样。这些问题的解决将使我们对过渡预测的理解有一个巨大的飞跃，并使LFC得以部署。该计划基于一个独特的研究团队，涵盖了该问题的所有理论、计算和实验方面，以及必要的专业知识，以确保该工作可以被行业部署。事实上，我们与欧洲宇航防务集团和空客英国公司的合作将使英国航空工业在开发新一代LFC机翼方面处于领先地位。该计划主要侧重于空气动力学，但我们开发的工具与广泛的问题相关。在化学工程领域，长期以来人们一直对如何在管道中有效地泵送流体以及与界面相关的流动不稳定性如何影响某些制造过程感兴趣。在地球科学中，在拓扑结构或人为障碍物后面的河床模式的形成是由描述翅膀上扰动开始的相同过程所控制的。同样，火星表面的格局也可以用携带沉积物的河流的不稳定机制来解释。在大气动力学和海洋学中，许多重要的流动现象与弯曲翼型上三维流动的基本不稳定性密切相关。我们的访客计划将确保我们的工作影响到这些和其他密切相关的领域，同样我们也意识到可以在空气动力学中使用有益的想法。

The world's oil supply is decreasing rapidly and over the next 10 or 20 years the price per barrel will spiral inexorably. Aviation is a significant consumer of oil and is also implicated in global warming through its generation of massive quantities of carbon dioxide and nitrogen oxide. Aircraft noise continues to be an increasingly important problem as airports expand. For these reasons aviation as we know it now will rapidly become unviable. There is no single solution to the problem and enormous changes to engines, airframe design, scheduling and indeed people's expectations of unlimited air travel are inevitable. Here we address one of the most important issues, improved aerodynamics, and develop the underpinning technology for Laminar Flow Control (LFC), the technology of drag reduction on aircraft. This will become the cornerstone of aircraft design. Even modest savings in drag of the order of 10% translate into huge savings in fuel costs and huge reductions in atmospheric pollution. Applications of the technology to military aircraft where range is often the main requirement and marine applications are similarly important. The development of viable LFC designs requires sophisticated mathematical, computational and experimental investigations of the onset of transition to turbulence and its control. Existing tools are too crude to be useful and contain little input from the flow physics. Major hurdles to be overcome concern:a) How do we specify generic input disturbances for flow past a wing in a messy atmosphere in the presence of surface imperfections, flexing, rain, insects and a host of other complicating featuresb) How do we solve the mathematical problems associated with linear and nonlinear disturbance growth in complex 3D flowsc) How do we find a criterion for the onset of transition based on flow physics which is accurate enough to avoid the massive over-design associated with existing LFC strategies yet efficient enough to be useable in the design officed) How can we use experiments in the laboratory to predict what happens in flight experimentse) How can we devise control strategies robust enough to be used on civilian aircraftf) How can we quantify the manufacturing tolerances such as say surface waviness or bumps needed to maintain laminar flowThe above challenges are huge and can only be overcome by innovative research based on the mathematical, computational and experimental excellence of a team like the one we have assembled. The solution of these problems will lead to a giant leap in our understanding of transition prediction and enable LFC to be deployed. The programme is based around a unique team of researchers covering all theoretical, computational, and experimental aspects of the problem together with the necessary expertise to make sure the work can be deployed by industry. Indeed our partnership with most notably EADS and Airbus UK will put the UK aeronautics industry in the lead to develop the new generation of LFC wings.The programme is focussed primarily on aerodynamics but the tools we develop are relevant in a wide range of problems. In Chemical Engineering there has long been an interest in how to pump fluids efficiently in pipelines and how flow instabilities associated with interfaces can compromise certain manufacturing processes. In Earth Sciences the formation of river bed patterns behind topology or man-made obstructions is governed by the same process that describes the initiation of disturbances on wings. Likewise surface patterns on Mars can be explained by the instability mechanisms of sediment carrying rivers. In Atmospheric Dynamics and Oceanography a host of crucial flow phenomena are intimately related to the basic instabilities of a 3D flow over a curved aerofoil. Our visitor programme will ensure that our work impinges on these and other closely related areas and that likewise we are aware of ideas which can be profitably be used in aerodynamics.