Optimisation of a variable sweep morphing wingtip

近年来，各部门大力推动减排，推动航空界制造更高效的飞机。飞机的效率通常可以通过延长翼展来提高，但是大型飞机的翼展受到机场设定的最大值的限制。因此，一些大型飞机，最著名的是波音777X，有折叠翼尖，允许他们人为地减少他们的翼展，以满足机场的规定，同时保持效率的好处。在目前的飞机上，这种折叠翼尖纯粹是为了减少跨度，并在飞行过程中确保“打开”。研究表明，在飞行过程中，通过被动（自由/弹簧铰链）或主动（驱动）控制翼尖铰链，有可能使翼尖铰链主动，以改善飞机的一些特性。目前正在进行的研究是垂直铰接翼尖，该项目的目的是研究这种铰接翼尖的替代几何形状和运动学。例如，在过去，可变后掠角已经应用于各种飞机的整个机翼，因为它允许在低速和高速下有效飞行。翼尖设计将涉及机翼外部几何形状和铰链位置的优化，以满足一系列所需的飞行条件，旨在创造一个效率更高的机翼。对于机翼比传统飞机更长更细的飞机来说，机翼结构的弯曲和扭转刚度较低，这导致它们在飞行中表现出更大的变形。当变形非常大时，变形后的飞机具有不同的气动特性，从而产生耦合问题。对于非常大的变形，非线性结构模型用于飞机，因为它们可以模拟典型线性模型中不存在的效果，例如几何硬化和跟随力效应。这种结构和气动耦合在某些飞行条件下会变得非常重要，其影响范围从不受欢迎的噪音到灾难性的结构故障或失去控制。空气动力学和结构的耦合被称为气动弹性，在帝国理工学院，一个开源的非线性求解器已经被创造出来，以模拟具有这种效应的飞机。在这个项目中，新的模块将在现有的工具上实现和使用，以模拟翼尖特性。将分析高柔性机翼上可变后掠翼尖的非线性气动弹性特性，以确保整个飞行包线的静态和动态稳定性。当前非线性气动弹性求解器的一个共同问题是运行速度慢，因此通常不适用于非研究环境。这个项目的另一个目标是用这样的求解器实现数据驱动的方法和模型，允许以最小的精度损失更快地生成数据。这包括从飞机的反应中提取主要特征，截断不太重要的影响，以创建一个问题的大幅降阶模型。这也开启了创建实时模型的可能性，可以在飞机上与控制系统一起使用，以实现更优化的控制策略。将研究和制定实现这一目标的首选战略。

In recent years, there has been a great push to reduce emissions in all sectors, creating a drive in the aviation community to create more efficient aircraft. The efficiency of an aircraft can generally be increased by lengthening its wingspan, however the span for larger aircraft is limited by a maximum value set by airports. Due to this, some large aircraft, most notably the Boeing 777X, having folding wingtips which allow them to artificially reduce their wingspan to meet airport regulations, whilst retaining the efficiency benefits. On current aircraft, such folding wingtips are used purely to reduce span and are secured "open" during flight. Research has shown potential to make wingtip hinges active during flight to improve some of the aircraft's characteristics, through either passive (free/sprung hinge) or active (actuated) control at the hinges. Current research is underway to investigate hinging the wingtips vertically, with the aim of this project being to investigate alternative geometries and kinematics of such hinged tips. Variable sweep angle has for example been applied to the whole wing in various aircraft in the past, as it allows for efficient flight at both low and high speeds. The wingtip design will involve optimisation of the wing external geometry and hinge placement for a range of required flight conditions, aiming to create a wing with increased efficiency. For aircraft with longer and more slender wings than a traditional aircraft, the wing structure has a lower bending and torsional stiffness, which leads to them demonstrating larger deformations in flight. When the deformations are significantly large, the deformed aircraft has different aerodynamic characteristics, creating a coupled problem. With very large deformations, non-linear structural models are used for the aircraft as they can simulate effects which are not present in a typical linear model, such as geometric stiffening and follower force effects. This structural and aerodynamic coupling can become very significant under some flight conditions, with effects ranging from undesirable noise to catastrophic structural failure or loss of control. The aerodynamic and structural coupling is known as aeroelasticity, and at Imperial College an open-source, non-linear solver has been created to simulate aircraft with such effects. During this project, new modules will be implemented and used on the existing tools to simulate the wingtip characteristics. The non-linear aeroelastic characteristics of the variable sweep wingtips on highly flexible wings will be analysed to ensure both static and dynamic stability across the flight envelope. A common issue with current non-linear aeroelastic solvers is they are slow to run, and so are often not practical for use in a non-research environment. An additional aim of this project is to implement data-driven methods and models with such solvers, allowing for faster generation of data with minimal accuracy loss. This involves extracting the dominant features from the aircraft's response, truncating the less significant effects to create a greatly reduced-order model of the problem. This also opens the possibility of creating real-time models, which can be used onboard aircraft for use with a control system for more optimal control strategies. The preferred strategies to achieve this are to be investigated and developed.