Turbulent structures and dynamic mechanisms in transonic airfoil buffet and in the interaction between airfoil wake and tailplane

跨音速翼型抖振以及翼型尾流与水平尾翼相互作用中的湍流结构和动力机制

• 批准号: 428244951
• 负责人: Dr.-Ing. Anne-Marie Schreyer
• 金额: --
• 依托单位: Lehrstuhl für Strömungslehre und Aerodynamisches Institut (AIA)
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/428244951?language=en
• 关键词: Turbulent; structures; dynamic; mechanisms; transonic

Close to the boundaries of the flight envelope, the transonic flow around modern transport aircraft is characterized by a complex coupling of unsteady aerodynamic phenomena at the wing and horizontal tailplane. On the suction side of transonic airfoils, local supersonic regions are terminated by a shock wave whose strength increases with angle of attack and Mach number, and can cause massive flow separation on the airfoil. The interaction between the shock and the boundary layer can incite periodic self-sustained shock oscillations (buffet), which can induce potentially detrimental structural oscillations (buffeting), thus limiting the life span and the usable flight envelope. In addition, these unsteady buffet-induced effects on the airfoil are also imprinted on the flow around the tailplane via the wake of the airfoil. This leads to complex flow configurations that have not yet been investigated and understood in detail. Therefore, the understanding and predictability of buffet mechanisms is necessary to safely expand the boundaries of the flight envelope. The prerequisite for this is a fundamental understanding of the interplay and potential superposition of different buffet mechanisms in 2D and 3D. The basis of these investigations is the initially decoupled consideration of the structurally stiff and vibration-affected cases, taking into account a stepwise transition from 2D, via 2.5D to 3D swept-wing geometries. The overall goal of TP6 is therefore the fundamental identification of the relationships between structural vibrations, sweep effects and the mechanisms of transonic buffet as well as their effects on the horizontal tailplane aerodynamics. To achieve this, high-resolution experimental data will be generated and assessed in synergy with the numerical data generated within the Research Unit. Detailed fundamental experiments are carried out on a swept tandem wing at a Reynolds number accessible to high-fidelity numerical methods. The synergetic evaluation with the measurement data acquired in the European Transonic Windtunnel (ETW) closes the gap to flight-realistic Reynolds numbers. Thus, flow physics and the influence of Reynolds number and airfoil sweep can be investigated, also supporting the further development of numerical methods. The implementation of synchronized DIC (Digital Image Correlation) and focusing-schlieren measurements allows the simultaneous acquisition of the coupled aerodynamic and structural dynamic phenomena. Stereo-Dual-Particle Image Velocimetry measurements provide access to velocity-field and acceleration information. Combined with advanced post-processing methods for the analysis of coherent turbulent structures (Proper Orthogonal Decomposition; Dynamic Mode Decomposition) and spectral analyses, this unique data set will allow insights that will significantly advance the understanding of transonic airfoil buffet and its influence on the tailplane aerodynamics at the boundary of the flight envelope.

在接近飞行包线边界处，现代运输机的跨声速绕流表现为机翼和水平尾翼上的非定常气动现象的复杂耦合。在跨声速翼型的吸力侧，局部超音速区域被激波终止，激波的强度随迎角和马赫数的增加而增大，并会在翼型上造成大范围的流动分离。激波和边界层之间的相互作用会激发周期性的自持激波振荡(抖振)，这可能会导致潜在的有害结构振荡(抖振)，从而限制了飞机的寿命和可用飞行包线。此外，这些非定常抖振对翼型的影响也通过翼型尾迹影响到尾翼周围的流动。这导致了复杂的流动形态，这些流动形态尚未被详细研究和了解。因此，对抖振机制的理解和可预测性对于安全地扩展飞行包线的边界是必要的。前提是对2D和3D中不同抖动机制的相互作用和潜在叠加有一个基本的了解。这些研究的基础是对结构刚性和受振动影响的情况的初始解耦考虑，考虑了从2D、通孔2.5D到3D后掠翼几何形状的逐步过渡。因此，TP6的总体目标是从根本上确定结构振动、后掠效应和跨音速抖振机理之间的关系，以及它们对水平尾翼气动特性的影响。为实现这一目标，将生成高分辨率实验数据，并与研究股内生成的数字数据协同进行评估。在高保真数值方法可获得的雷诺数条件下，对后掠串列机翼进行了详细的基础实验。与在欧洲跨音速风洞(ETW)获得的测量数据的协同评估缩小了与飞行现实雷诺数的差距。因此，可以研究流动物理以及雷诺数和翼型后掠的影响，这也为数值方法的进一步发展提供了支持。同步DIC(数字图像相关)和聚焦纹影测量的实施允许同时采集耦合的空气动力和结构动力学现象。立体-双粒子图像测速仪测量提供了速度场和加速度信息。结合用于分析相干湍流结构(适当的正交分解；动态模式分解)和频谱分析的先进后处理方法，这一独特的数据集将使人们能够深入了解跨音速翼型抖动及其对飞行包线边界处机翼空气动力学的影响。