Within the transonic regime, the aeroelastic problems exhibit many unique characteristics compared with subsonic and supersonic cases. Although a lot of research has been carried out in this field, the underlying mechanisms of these complex phenomena are not clearly understood yet, resulting in a challenge in the design and use of modern aircraft. This review summarizes the recent investigations on nonclassical transonic aeroelastic problems, including transonic buzz, reduction of transonic buffet onset, transonic buffeting response and frequency lock-in phenomenon in transonic buffet flow. After introducing the research methods in unsteady aerodynamics and aeroelastic problems, the dynamical characteristics as well as the physical mechanisms of these phenomena are discussed from the perspective of the fluid mode. In the framework of the ROM (reduced order model) -based model, the dominant fluid mode (or the eigenvalue) and its coupling process with the structural model can be clearly captured. The flow nonlinearity was believed to be the cause of the complexity of transonic aeroelasticity. In fact, this review indicates that the complexity lies in the decrease of the flow stability in the transonic regime. In this condition, the fluid mode becomes a principal part of the coupling process, which results in the instability of the fluid mode itself or the structural mode, and thus, it is the root cause of different transonic aeroelastic phenomena.

中文翻译：

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跨音速气动弹性：流体模式的新视角

在跨音速范围内，与亚音速和超音速情况相比，气动弹性问题表现出许多独特的特征。尽管在该领域进行了大量研究，但这些复杂现象的潜在机制尚不清楚，这给现代飞机的设计和使用带来了挑战。这篇综述总结了最近对非经典跨音速气动弹性问题的研究，包括跨音速嗡嗡声、减少跨音速抖振开始、跨音速抖振响应和跨音速抖振流中的频率锁定现象。在介绍了非定常空气动力学和气动弹性问题的研究方法之后，从流体模态的角度讨论了这些现象的动力学特性和物理机制。在基于 ROM（降阶模型）的模型的框架中，可以清楚地捕获主导流体模式（或特征值）及其与结构模型的耦合过程。流动非线性被认为是造成跨音速气动弹性复杂性的原因。事实上，这篇综述表明，复杂性在于跨音速状态下流动稳定性的降低。在这种情况下，流体模态成为耦合过程的主要部分，导致流体模态本身或结构模态的不稳定性，从而成为不同跨音速气弹现象产生的根本原因。流动非线性被认为是造成跨音速气动弹性复杂性的原因。事实上，这篇综述表明，复杂性在于跨音速状态下流动稳定性的降低。在这种情况下，流体模态成为耦合过程的主要部分，导致流体模态本身或结构模态的不稳定性，从而成为不同跨音速气弹现象产生的根本原因。流动非线性被认为是造成跨音速气动弹性复杂性的原因。事实上，这篇综述表明，复杂性在于跨音速状态下流动稳定性的降低。在这种情况下，流体模态成为耦合过程的主要部分，导致流体模态本身或结构模态的不稳定性，从而成为不同跨音速气弹现象产生的根本原因。