微小结构化肋诱发涡流增强凹陷涡对流冷却机理研究

A fundamental study will be conducted on micro-structured ribs induced vortex flow improving convective cooling performance of dimple-generated vortex under stationary and rotating conditions with the aim of developing high efficient internal cooling technology of gas turbine high-temperature components. In this research, micro-structured ribs will be used to induce vortex flow interacting with the dimples, so as to improve the flow structure inside the dimples and increase the heat transfer on the dimpled surface, and a high-efficiency cooling technology will be developed based on the effective flow control by the micro-structured rib-dimple hybrid structure. In the experimental study, a transient liquid crystal technique will be used for detailed heat transfer measurements in order to obtain high-resolution surface temperature and local heat transfer distribution, and thereby convective heat transfer characteristics will be examined intensively on the surface with micro rib-dimple compound structures, and the models for heat transfer and flow friction of the cooling structures can be quantitatively determined which reflects the effects of the rotation, flow and geometrical parameters. On the other hand, Particle Image Velocimetry (PIV) and oil film flow visualization techniques will be used to capture the detailed characteristics of turbulent boundary layer flow over the micro rib-dimple structures, and parallelly a high-resolution numerical computations on the turbulent flow using detached eddy simulation (DES) will also be conducted, which can systematically and quantitatively clarify the vortex flow production and development due to the interactions between the flow and the complex structures, and clarify the mechanisms in the flow control and the heat transfer enhancement over the novel micro structured rib-dimple hybrid cooling structures. This research will produce valuable theoretical basis for developing future innovative cooling technologies for gas turbine engines.

本项目以燃气轮机/航空发动机高温部件内部高效冷却为研究背景，开展静态和旋转条件下微小结构化肋诱发涡流增强凹陷涡对流冷却机理研究。本项目拟通过微小结构化肋诱发涡流并与凹陷涡相互作用，从而改善凹陷涡内部流场并显著提高凹陷表面传热性能，发展基于微小结构化肋-凹陷涡复合结构流动控制的高性能冷却技术。拟采用瞬态液晶热像技术进行传热测量，获得高分辨率壁面温度以及局部传热分布，揭示微小肋-凹陷涡复合结构表面对流传热特征，建立旋转效应、流动及结构参数对传热及流阻影响规律的模型。本研究还将应用粒子图像速度仪（PIV）和油膜流动显示技术获得该复合冷却结构近壁面湍流流场特征，并结合分离涡模拟（DES）方法进行高精度的数值计算，透彻地揭示流体与复杂结构相互作用下涡流的发生及发展特征，阐明静态和旋转条件下微小结构化肋-凹陷涡复合结构表面流动控制与强化传热的机理性规律，为发展先进燃气轮机高温部件冷却技术奠定理论基础。

提高涡轮前燃气温度和压比是提高燃气轮机/航空发动机热力性能的主要途径，这给高温涡轮叶片冷却带来了重大挑战。针对常规的涡轮叶片内部扰流肋冷却接近极限的现状，必须开展先进复合内部冷却技术研究。本项目以燃气轮机/航空发动机高温涡轮叶片内部高效冷却为研究背景，开展静态和旋转条件下微小结构化肋诱发涡流增强凹陷涡对流冷却机理研究。本项目的创新思想在于通过表面微小结构化肋诱发涡流并与凹陷涡相互作用，从而改善凹陷涡内部流场并显著提高凹陷表面传热性能，发展基于微小结构化肋-凹陷涡复合结构流动控制的高性能冷却技术。本项目采用了实验与数值模拟相结合的研究方法对表面微小结构化肋、凹陷涡以及微肋-凹陷复合结构流动与传热特性进行了详细的研究，揭示和分析了相关的涡流及强化传热机理。在静态流动传热实验研究中，采用了瞬态液晶热像技术进行了全复杂表面高精度的传热测量，获得高分辨率壁面温度以及局部传热分布，揭示微小肋-凹陷涡复合结构表面对流传热特征。本研究还应用了粒子图像速度仪（PIV）和油膜流动显示技术获得该复合冷却结构关键位置近壁面湍流流场特征，并结合分离涡模拟（DES）方法进行了高精度的数值计算，获得表面微小肋和凹陷涡非稳态流动传热规律，透彻地揭示了静态条件下流体与表面微肋-凹陷复杂结构相互作用下涡流的发生及发展特征。另外在本项目研究中，还利用课题组已建立的高参数旋转传热试验装置，开展了旋转条件下微小肋-凹陷涡复合结构冷却通道湍流传热与流阻实验研究，首次获得了静态和旋转条件下雷诺数范围为1万-10万的整套传热实验数据，建立了旋转效应和流动雷诺数相关的实验关联式；并通过数值模拟分析了旋转条件下的涡流及传热特征。因此，本项目丰富的基础研究获得了静态和旋转条件下微小结构化肋-凹陷涡复合结构表面流动控制与强化传热的机理性规律，为发展先进燃气轮机/航空发动机涡轮叶片内部复合对流冷却以及燃烧室双层壁对流冷却设计技术奠定了理论基础。