局部非周期性内流环境下的孔隙射流扰动机理

The research purpose of this project is to investigate the interaction between local non-periodic flow field and and the secondary hole/gap jet flow in high pressure gas turbine through experiments and numerical simulation. This project will provide fundamental theory and analysis of flow mechanism for the design of high pressure gas turbine under the real operation condition. The major research contents include: 1) the interaction mechanism between non-periodic and nonuniform inlet boundary conditions and hole/gap jet flow, including inlet rotational flow, hot strake and their combined effects on inlet nozzle guide vanes. 2) considering the influence of arbitrary geometry, especially the nonaxisymmetry endwall, complex fillets and novel concepts will be redesigned as non-periodic form in order to gain a better aerodynamic ad heat transfer performance. 3) the mechanism of non-periodic flow generated by moving boundary layer, different trailing edge cooling jet, which affect the hole/gap cooling jet flow in turbine cascade. 4) developing the low-dissipation scheme with kinetic energy conservation, which is called KEP-LES and based on unstructured mesh; applying KEP-LES scheme on numerical simulation of hole/gap cooling jet flow under non-periodic environment inside high pressure turbine and providing detailed flow field for analyzing the experimental phenomenon. Finally, the fundamental theory of interaction between local non-periodic flow filed and and the secondary hole/gap jet flow in high pressure gas turbine will be built, and the corresponding experimental and numerical analysis system will also be established. The project will make effort to improve the aerodynamic and cooling performance of advanced gas turbine by providing theoretical references and engineering methods.

本项目通过实验和数值模拟相结合的手段探索局部非周期性流场对高压燃气透平孔隙流动的扰动规律，为适应真实运行环境的高压透平设计提供理论依据和机理分析基础。主要研究内容包括：1）局部非周期非均匀进口边界条件对孔隙射流流动的影响机理，包括进口旋流、热斑及其综合作用等；2）考虑非轴对称端壁、复杂倒角和新概念孔隙等非规则几何结构对孔隙流动的影响，对高压透平相邻叶栅通道中的孔隙射流结构进行局部非周期性设计；3）研究运动边界层及差异化非对称上游尾缘射流引发的局部非周期性流动对叶栅内孔隙射流的影响机理；4）发展基于非结构网格的动能守恒数值格式KEP-LES，从流动机理出发为该数值方法应用于局部非周期性流场计算提供数值实验基础。最终，本项目将提炼和总结一套完整的孔隙射流与局部非周期性流动环境相互作用机理，并建立相应的实验/模拟分析系统，为进一步提高先进燃气轮机的气动冷却性能提供理论与方法。

为配合航空发动机和燃气轮机重大专项研究，推进透平气热及冷却设计系统构建，本项目深入探究了局部非周期性流场对高压燃气轮机透平孔隙流动的扰动规律，发展了高精度数值方法和湍流模拟技术，构建了气膜孔型及排布的设计优化系统。. 本项目从局部非周期性进口边界条件对叶栅通道内部孔隙射流的影响机制入手，通过数值计算方法实现了局部非周期性进口的定量模拟，深入探究了旋流与热斑同时作用下透平通道中涡结构及温度分布的非线性叠加特性，并通过压力敏感漆实验方法系统地研究了局部非周期性透平入口旋流对叶栅前缘、压力面、吸力面及端壁的气膜冷却特性。进而本研究结合真实燃气轮机结构，探究了导叶前缘及叶片间装配缝的气膜冷却特性，根据局部非周期性气热特性设计了冷却孔隙结构，形成新概念的相邻叶栅通道差异化孔隙结构，提出了透平导叶端壁横向流动对气膜冷却想研究的简化模型，并开发了基于多精度代理模型的气膜孔优化程序。本项目探究了燃烧室出口旋流对透平导叶通道中马蹄涡、通道涡和尾迹涡的影响作用，采用高精度DDES方法探究了端壁复杂涡系结构与尾迹涡相互作用下的破碎机理；研究了近端壁区域的气膜孔冷却气扩散机理。同时，本项目发展了基于高精度低耗散数值格式的混合RANS/LES模拟系统，及基于非结构网格的高精度湍流自适应模拟系统，更精确地模拟了跨音速高压透平级通道内部的激波、尾迹、边界层等的流动现象以及激波和尾迹的相互干涉。. 综上，本项目系统地探究了燃气轮机透平中的局部非周期性流动机理及其对气膜冷却的影响作用，发展了高精度数值计算方法，并建立了气膜孔型优化方法及端壁气膜孔排布设计方法，为提高我国先进航空发动机和燃气轮机的性能提供了理论和方法。