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

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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.