Large-eddy simulations and modal reconstruction of laminar transonic buffet
Large-eddy simulations and modal reconstruction of laminar transonic buffet
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DOI：
10.1017/jfm.2022.471
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发表时间：
2021-10
影响因子：
3.7
通讯作者：
Pradeep Moise;M. Zauner;N. Sandham
中科院分区：
文献类型：
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作者：
Pradeep Moise;M. Zauner;N. Sandham
跨音速抖振是指在跨音速机翼绕流中观察到的激波的自持周期性运动，它能限制飞机的飞行包线。根据激波根部的边界层特性，抖振被分为层流和湍流，并且这两种抖振的机理被认为是不同的（Dandois等人，流体力学杂志，第18卷，2018年，pp. 156-178）。本文通过对各种参数进行大涡模拟（LES），研究了各种流动参数（自由马赫数、雷诺数、后掠角和迎角）对无限大机翼（达索航空公司的超临界V2 C机翼）层流跨音速抖振的影响。一个频谱正交分解识别出与抖振相关的低频模式和与旋涡脱落相关的高频尾流模式。仅基于前者的流动重建显示了伴随激波运动的周期性边界层分离和再附着。仅基于尾流模态的模态重构表明，Dandois等人报道的分离气泡呼吸现象是由于该模态。总之，这些结果表明，层流和湍流抖振的物理机制是相同的。还在零入射角下模拟抖振。激波出现在两个翼型表面上，并彼此异相振荡，表明发生了I型抖振（Giannelis等人，Aerosp Sci.技术人员：第18卷，2018年，pp. 89-101）在超临界翼型上。这些结果表明，不同的抖振类型的机制是相同的。
Abstract Transonic buffet refers to the self-sustained periodic motion of shock waves observed in transonic flows over wings and can limit the flight envelope of aircraft. Based on the boundary layer characteristics at the shock foot, buffet has been classified as laminar or turbulent and the mechanisms underlying the two have been proposed to be different (Dandois et al., J. Fluid Mech., vol. 18, 2018, pp. 156–178). The effect of various flow parameters (freestream Mach and Reynolds numbers and sweep and incidence angles) on laminar transonic buffet on an infinite wing (Dassault Aviation's supercritical V2C aerofoil) is reported here by performing large-eddy simulations (LES) for a wide range of parameters. A spectral proper orthogonal decomposition identified the presence of a low-frequency mode associated with buffet and high-frequency wake modes related to vortex shedding. A flow reconstruction based only on the former shows periodic boundary-layer separation and reattachment accompanying shock wave motion. A modal reconstruction based only on the wake mode suggests that the separation bubble breathing phenomenon reported by Dandois et al. is due to this mode. Together, these results indicate that the physical mechanisms governing laminar and turbulent buffet are the same. Buffet was also simulated at zero incidence. Shock waves appear on both aerofoil surfaces and oscillate out of phase with each other indicating the occurrence of a Type I buffet (Giannelis et al., Aerosp. Sci. Technol., vol. 18, 2018, pp. 89–101) on a supercritical aerofoil. These results suggest that the mechanisms underlying different buffet types are the same.