Analysis of transonic buffet using dynamic mode decomposition
Analysis of transonic buffet using dynamic mode decomposition
复制标题
DOI：
10.1007/s00348-020-03111-5
复制
发表时间：
2021-03
影响因子：
2.4
通讯作者：
A. Feldhusen-Hoffmann;C. Lagemann;S. Loosen;P. Meysonnat;M. Klaas;W. Schröder
中科院分区：
文献类型：
--
作者：
A. Feldhusen-Hoffmann;C. Lagemann;S. Loosen;P. Meysonnat;M. Klaas;W. Schröder
超临界翼型周围的自助餐流场主要由机翼吸力侧的自持续激波振荡控制。理论假设这种不稳定性是由激波下游流场扰动的反馈回路驱动的，而激波的上游传播部分是由声波产生的。高速粒子图像测速测量进行了研究这一反馈回路在跨音速自助餐流超过一个超临界德拉2303翼型。自由流马赫数为，攻角为，弦基雷诺数为。对得到的速度场进行稀疏化动态模态分解，识别出对颤振流场贡献最大的主导动力特征。发现了两个明显的动态模式，这证实了所提出的反馈回路的两个主要特征的存在。一种模态与激波振荡频率有关，其形状包括激波的运动和激波下游再循环区域的耦合脉动。另一个显式模式表示形成所提出的反馈回路的下游传播部分的干扰。这种模式的频率对应于由这些下游传播扰动产生的声波的频率，这些声波形成了所提出的反馈回路的上游传播部分。在本研究中，强调了后处理，即DMD，以证实该涡旋模式的存在。正是这种涡旋模式通过兰姆矢量激发了激波振荡。基于测量数据的DMD结果证实了数值结果，即主导的自助餐和涡旋模式与Lee提出的反馈回路很好地吻合。图形抽象
The buffet flow field around supercritical airfoils is dominated by self-sustained shock wave oscillations on the suction side of the wing. Theories assume that this unsteadiness is driven by a feedback loop of disturbances in the flow field downstream of the shock wave whose upstream propagating part is generated by acoustic waves. High-speed particle-image velocimetry measurements are performed to investigate this feedback loop in transonic buffet flow over a supercritical DRA 2303 airfoil. The freestream Mach number is, the angle of attack is, and the chord-based Reynolds number is. The obtained velocity fields are processed by sparsity-promoting dynamic mode decomposition to identify the dominant dynamic features contributing strongest to the buffet flow field. Two pronounced dynamic modes are found which confirm the presence of two main features of the proposed feedback loop. One mode is related to the shock wave oscillation frequency and its shape includes the movement of the shock wave and the coupled pulsation of the recirculation region downstream of the shock wave. The other pronounced mode represents the disturbances which form the downstream propagating part of the proposed feedback loop. The frequency of this mode corresponds to the frequency of the acoustic waves which are generated by these downstream traveling disturbances and which form the upstream propagating part of the proposed feedback loop. In this study, the post-processing, i.e., the DMD, is highlighted to substantiate the existence of this vortex mode. It is this vortex mode that via the Lamb vector excites the shock oscillations. The measurement data based DMD results confirm numerical findings, i.e., the dominant buffet and vortex modes are in good agreement with the feedback loop suggested by Lee.Graphic abstract