Experimental Study on Ground Interaction and Breakdown of Generic Transport Aircraft Wakes with Focus on Final Approach and Landing

大型运输机在最后进场和着陆过程中的尾涡特性对飞机工业和机场运营具有很大的意义。联邦航空管理局（FAA）和欧洲航空安全管理局（Eurocontrol）目前的努力旨在设计一种改进的尾涡咨询系统（WVAS），以增加机场的容量，同时保持甚至超过当前的安全标准。因此，在国际项目重新分类（RECAT）的框架内，工作正在进行中，以在2020年之前建立飞机的动态成对分离。尽管在过去几年中做出了广泛的努力，但仍然非常需要研究，以了解复杂的三维现象，特别是发生在靠近地面的地方。在欧洲网络WakeNET3的报告中，研究领域明确制定了实现这些雄心勃勃的目标。至于实验的挑战，非线性飞机轨迹的调查，以及弯曲的涡流轨迹和调查的涡流行为在地面附近。目前的研究考虑到实际的飞机着陆的问题进行数值计算，也在全尺寸的领域活动的形式，使用激光光学测量技术（LIDAR）。在这些研究的框架内，还研究了地面措施（板线），以促进跑道附近的涡流破裂。据申请人所知，关于涡流破裂（包括着陆的实际影响）的可比比例实验目前还没有在文献中出现。以前的研究涉及地面效应中的双涡系统已经使用地面平行模型轨迹进行。特别是末端效应，这是很重要的，在这种情况下，已被排除故意。因此，拟议的研究的目标是实现新的见解着陆飞机尾流的崩溃机制，并使有关的二次不稳定性的传播速度的预测。为此，必须尽可能逼真地模拟实际着陆。特别关注的是模型轨迹和升力系数的时间演变，这需要模拟最终的方法，捕捉地面效应，以及模拟一个现实的耀斑和着陆。因此，本研究旨在有助于建模，仿真和预测全尺寸飞机尾流在着陆期间和之后。

The wake vortex characteristics of large transport aircraft on final approach and during touchdown are of large interest for the aircraft industry and to the same extent for airport operations. Current efforts of Federal Aviation Administration (FAA) and Eurocontrol aim at designing a modified Wake Vortex Advisory System (WVAS) to increase the capacity of airports, while maintaining or even exceeding current safety standards.Therefore, within the framework of the international project Re-Categorization (RECAT) work is in progress, in order to establish a dynamic pair-wise separation of aircraft by 2020. Despite extensive efforts over the last years, still there is a great need for research in order to understand the complex three-dimensional phenomena, which especially occur close to the ground. In the report of the European network WakeNET3 fields of research are clearly formulated to reach these ambitious goals. As for experimental challenges, the investigation of non-linear aircraft trajectories is stated, as well as curved vortex trajectories and the investigation of the vortex behavior near the ground.Current studies on the subject considering actual landings of an aircraft are conducted numerically, and also in form of full-scale field campaigns using laser-optical measurement techniques (LIDAR). Within the framework of these studies also ground based measures (plate lines) are investigated to promote vortex breakdown close to the runway.To the knowledge of the applicant, comparable scaled experiments regarding the vortex breakdown including the actual effects of landing are currently not represented in literature. Previous studies involving two-vortex systems in ground effect have been carried out using ground parallel model trajectories. Especially end effects, which are important in this context, have been excluded intentionally.Therefore, the goal of the proposed study is to achieve novel insights into the breakdown mechanisms of landing aircraft wakes, and to enable predictions of the propagation speed of the involved secondary instabilities. For this purpose the actual landing has to be simulated as realistic as possible. Special focus is put on the model trajectory and the temporal evolution of the lift coefficient, which requires to simulate the final approach, capturing the ground effect, as well as to simulate a realistic flare and touchdown. As a result this study intends to contribute to modeling, simulation and prediction of full-scale aircraft wakes during and after landing.