Studies on the Development of Massively Separated Wakes of Aircraft

商用飞机在飞行边界的行为与复杂的流体-物理过程有关，其特征在实验和数值上都是一个挑战。在大迎角下，机翼上会发生流动分离，导致非定常的湍流尾迹。这些湍流结构向下游传播，并与尾面相互作用。本文主要研究了尾流分离、尾迹传播及其与尾翼的相互作用，重点研究了欧洲跨音速风洞(ETW)ESWIRP项目中的CRM飞机外形及其在普通CRM飞机外形上的测量。在第一个项目阶段，完成了时间分辨PIV尾迹测量的处理。研究了现代尺度分辨数值方法在分离尾流数值模拟中的适用性。对实验数据和数值数据的协同分析为大迎角下大规模分离尾流的形成和行为提供了深入的见解。数据集的统计和频谱分析表明，数值方法适用于尾流物理和湍流脉动的预报。在第二工程阶段，将利用所获得的知识对尾流物理进行深入的分析。第一步是检查计算和实验研究之间的差异在多大程度上影响结果的可比性。除了第一阶段在大迎角和大规模分离情况下进行的调查外，现在还将考虑较小的攻角，以便分析涉及较小尺度流动分离的飞行条件。为此，将首先确定适用于这些流动条件的混合RAN/LES方法。这些方法的具体验证将涉及现有的ESWIRP测量结果，以及在申请人部门使用简化配置进行的风洞测量。在前人研究成果的基础上，分析了尾翼对尾迹的影响。为此，将在考虑不同的尾翼入射角的情况下进行调查，并作为参考，不考虑尾翼。流体物理研究将基于统计和频谱分析以及POD或DMD等模态方法，从而详细研究尾迹中的瞬时波动以及机翼和尾翼载荷的波动。攻角和尾部入射角的变化有助于更好地了解分离尾迹的行为及其在各种可能的流入条件下与尾部的相互作用。

The behavior of commercial aircraft at the flight boundaries is associated with complex fluid-physical processes, the characterisation of which presents a challenge both experimentally and numerically. Flow separation occurs on the wing at high angles of attack, resulting in an unsteady turbulent wake. These turbulent structures are propagated downstream and interact with the tail plane. The main focus of this research project is the study of the interaction between flow separation, wake propagation and its interaction with the tail plane.The project focuses on the CRM aircraft configuration and associated measurements carried out during the EU project ESWIRP in the European Transonic Wind Tunnel (ETW) on the generic CRM aircraft configuration. During the course of the first project phase, the processing of time-resolved PIV wake measurements was completed. The suitability of modern scale-resolving numerical methods for the simulation of separated wake flows was investigated. Synergetic analyses of the experimental and numerical data have provided insights into the formation and behavior of massively detached wake flows at high angles of attack. Statistical and spectral analyses of the data sets have shown that the numerical methods are suitable for the prediction of the flow physics and the turbulent fluctuations in the wake.In the second project phase, the gained knowledge will be used to carry out in-depth analyses of the wake physics. The first step is to examine to what extent the differences between the computational and experimental studies influence the comparability of the results. In addition to the investigations carried out in the first phase at a high angle of attack and massive separation, smaller angles of attack will now also be considered in order to analyze flight conditions involving a smaller scale flow separation. To this end, hybrid RANS/LES methods suitable for these flow conditions will be identified first. Specific validation of the methods will involve both the existing ESWIRP measurement results and, in addition, wind tunnel measurements carried out at the applicant's department using a simplified configuration. Based on previous findings, the influence of the tail plane on the wake will be analyzed. For this purpose, investigations will be carried out under consideration of different tail plane incidence angles and, as a reference, without the tail plane. Fluid physics studies will be based on statistical and spectral analyses as well as modal methods such as POD or DMD, whereby both the transient fluctuations in the wake and the fluctuating wing and tail plane loads will be examined in detail. The variations of the angle of attack and tail incidence serve to obtain an enhanced understanding of the behaviour of the separated wake and its interaction with the tail over a wide range of possible inflow conditions.