Studies on the Development of Massively Separated Wakes of Aircraft

商用飞机在飞行边界处的行为与复杂的流体物理过程有关，对其特征的描述在实验和数值上都提出了挑战。在大迎角时，机翼上发生流动分离，形成非定常湍流尾迹。这些湍流结构向下游传播并与尾平面相互作用。本课题的研究重点是流动分离、尾迹传播及其与尾翼的相互作用。该项目的重点是CRM飞机的配置和相关的测量，这些测量是在欧盟项目ESWIRP期间在欧洲跨音速风洞（ETW）进行的通用CRM飞机配置。在项目的第一阶段，完成了时间分辨PIV尾迹测量的处理。研究了现代尺度解析数值方法在分离尾流模拟中的适用性。实验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见解。数据集的统计分析和谱分析表明，数值方法适用于尾迹流动物理和湍流波动的预测。在第二个项目阶段，所获得的知识将用于对尾流物理进行深入分析。第一步是检验计算研究和实验研究之间的差异在多大程度上影响结果的可比性。除了在第一阶段对大迎角和大规模分离进行的调查外，现在还将考虑较小的迎角，以便分析涉及较小规模流动分离的飞行条件。为此，将首先确定适合这些流动条件的混合RANS/LES方法。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。在前人研究的基础上，分析了尾翼对尾流的影响。为此，将在考虑不同尾翼入射角的情况下进行研究，并以不考虑尾翼为参考。流体物理研究将以统计和频谱分析以及POD或DMD等模态方法为基础，通过这些方法，将详细研究尾迹的瞬态波动以及机翼和尾翼载荷的波动。迎角和尾翼入射角的变化有助于更好地理解分离尾流的行为及其在各种可能的流入条件下与尾翼的相互作用。

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.