壁面粗糙度在不同模态扰动主导的高超声速边界层转捩中的作用与机理

Hypersonic boundary layer transition has become one of key scientific problems that restricts the breakthrough of hypersonic technologies, and is also a hot and difficult issue in current academic research. Due to the great sensitivity to external disturbances, hypersonic transitions are remarkably affected by the wall roughness. Considering the complexity and significance, the influence mechanism of the wall roughness in the hypersonic transition requires thorough and clear understanding. Based on the direct numerical simulation, the present project explores the effects of wall roughness on the hypersonic boundary layer transition from the perspective of discrete mode perturbations, aiming at revealing the evolution characteristics and mechanisms of Tollmien-Shlichting mode and Mack mode disturbances, and further clarifying the corresponding nonlinear mode interactions. Finally, the correlations between wall roughness parameters and disturbance evolution characteristics are quantitatively established. This project not only facilitates the comprehension on the effects of wall roughness on hypersonic boundary layer transition, but also provides theoretical guidance for the reasonable control strategy, which shows great academic significance and engineering value.

转捩问题已成为制约高超声速技术突破的关键科学问题之一，也是当前学术研究的热点与难点。高超声速转捩对外界扰动极其敏感，由壁面粗糙度引起的扰动作用至关重要。鉴于壁面粗糙度作用的复杂性与重要性，高超声速转捩中壁面粗糙度的影响机制亟需更深入、清晰的认识。本项目拟采用直接数值模拟方法，从单一类型模态扰动角度出发，探究高超声速边界层转捩中壁面粗糙度的影响及其机理，揭示壁面粗糙度对T-S模态及Mack模态扰动波的作用特征，阐明壁面粗糙度作用下转捩中后期的非线性作用机制，建立壁面粗糙度参数与扰动波演化特征关联性的定量化描述。本项目的研究工作不仅有助于深刻理解高超声速边界层内壁面粗糙度的转捩影响机理，同时能够为边界层转捩的合理控制提供理论指导，具有重要的学术意义和工程价值。

本项目基于数值模拟手段，开展了高超声速边界层转捩中壁面粗糙度的作用机理与影响特性研究，重点探究了转捩的非线性作用机制。首先，开展了第一模态斜波扰动、第二模态基频扰动两类模态类型扰动的平板边界层稳定性研究，获取了扰动关键模态特征信息，为后续稳定性分析及DNS研究提供了重要数据支撑。其次，发展了一种完全的高速边界层三维全局失稳分析的迭代求解方法，提升了大规模求解的迭代效率。在此基础上，针对壁面粗糙度扰动的高速边界层稳定性特征完成了三维全局稳定性分析，确认了对称/反对称模态两类主导扰动模态特征及其增长规律。最后，采用直接数值模拟手段，揭示了典型壁面粗糙元诱导的高速边界层转捩过程特征与作用机制，建立了对壁面粗糙元诱导边界层转捩问题的深入认识，同时探究了壁面粗糙度与壁面吹吸扰动共同作用下的高速边界层转捩内在机制与作用规律。项目研究成果为高速边界层转捩的准确预测及合理控制提供了一定的理论指导，具有重要的科学意义与应用价值。.项目执行期间，共发表SCI论文8篇，其中第一作者或通讯作者5篇；授理或授权国家发明专利3项；培养研究生9名。