旋转壁湍流的统计规律及机理研究

Wall-bounded turbulence with system rotation is a common phenomenon in turbomachinery. However, its underlying mechanism and reliable turbulence models are still open questions around the world. Understanding and knowledge of the physical mechanism in rotating wall-bounded turbulence is the foundation of the development on reliable turbulence models, and will play an important role in the advanced design, research and development of turbomachinery. The present project will carry out a series of direct numerical simulations on three canonical test cases in rotating wall-bounded turbulence, including the streamwise-rotating turbulent channel flows, the spanwise-rotating turbulent channel flows and the spanwise-rotating turbulence plane-Couette flow, to create a credible, high-accuracy database. We aimed to study the flow statistics, flow structures and intrinsic mechanism in these three canonical test cases by analyzing this database. Furthermore, we will explore the universal statistical law, flow structures and physical mechanism that might exist among these three different canonical cases. The implementation of this project will provide reliable data basis and physical understanding for the modelling study in rotating wall-bounded turbulence.

旋转壁湍流是叶轮机械里非常典型的流动现象，其机理及可靠湍流模式在世界范围都尚未完全解决。了解和掌握旋转壁湍流的物理机理是发展可靠湍流模式的基础，进而对将来叶轮机械的先进设计与研发有着重要的意义。本项目以流向旋转槽道湍流，展向旋转槽道湍流及展向旋转平板Couette湍流等三种旋转壁湍流标准模型为研究对象，通过直接数值模拟的手段建立可信的高精度数据库，并分析这三种标模中的统计规律、流动结构及物理机理。在此基础上，我们将探析其中可能存在的共性的统计规律、流动结构及物理机理。该项目的实施将为旋转壁湍流的建模研究提供可靠的数据基础及物理认识。

旋转壁湍流是航空发动机等叶轮机械中的关键湍流问题之一，了解旋转壁湍流的物理机理是发展可靠湍流模式的基础，进而对将来叶轮机械的先进设计与研发有着重要的意义。经过四年的研究，本项目初步建立了包含流向旋转槽道湍流、展向旋转槽道湍流、展向旋转平板Couette湍流的高精度数据库，并获得了新统计规律、流动结构和物理机理。在展向旋转槽道湍流中我们发现了流向速度脉动高阶矩满足线性律，平均速度线性律的截距具有对数标度律行为，在流动中存在羽流、内波和羽流簇等流动结构，并提出用二维三分量简化模型来理解线性律斜率，其来源于流向速度分量方程中主导的科氏力项。在展向旋转平板Couette湍流中，我们发现了其中存在多湍流态现象，且该多态现象可以在不同雷诺数和旋转数下存在，多湍流态现象中大尺度涡卷结构占据重要地位，并结合降维方法和分叉分析从数学上分析了双重湍流态的存在可能。本项目的研究不仅拓宽了人们对旋转壁湍流的认识，也有效拓展了人们对经典湍流理论中各态遍历假设的认识。