涡轮导向叶片成型孔气膜射流与叶栅主流的相干机制及共轭传热

The development of advanced gas turbine engines results in continual increase of the oprerating temperature, which leads to a greated thermal stress imposing on the turbine components. Thus highly novel active cooling techniques are essential to protect the turbine componet from overheating. Film cooling, as an efficient technique, has been widely employed to protect the external surface of turbine component from the hot mainstream by ejecting the internal coolant through film holes. How to improve the cooling capacity with limited coolant utilization is a tremendous challenge, also a vital foundmental problem in the engineering thermal sicence. The present project aims at the highly novel film jet cooling featured by “efficient shaped hole”, illustrting its interaction mechanism with the primary flow in the cascade channel as well as conjugate heat transfer mechanism with internal cooling air in a real cooling configuration. Three commonly thermal science problems in the engineering applications are outlined as the following: 1) Coherent structure and cooling enhancement of shaped-hole film jet in a complex primary flow as well as the inherent difference in relative to no pressure gradient mainflow. 2) Predominant factors affecting the primary near-wall flow and aerodynamic-thermal performance synergy. 3) Inherent relationship between the “enhanced cooling capacity” of shaped-hole film jets and the “limited coolant utilization” in the turbine blade cooling configuration design. The present project provides more comprehansive and deep understandings on the shaped-hole film jet cooling, behaving significant therotical and applied values in the innovation and development of turbine guide vane cooling techniques for advanced gas turbine engines.

高性能燃气涡轮发动机热力循环温度的不断提高导致热端部件热负荷急剧增加，发展和创新高效的热端部件气膜冷却技术，是应对“在减少冷却空气系数的情况下实现热端部件冷却能力提升”这一技术挑战的一个重要需求，也是工程热物理学科面临的一个重大基础科学问题。申请课题以“高效异形”成型孔气膜射流为核心，凝练出其与叶栅通道主流的相干机制、冷却结构内部气流的共轭传热机制这两个核心的科学问题展开研究，以期揭示：1) 成型孔气膜射流在复杂主流环境中的拟序结构演变及其强化冷却效果与无压力梯度主流存在的内在特征差异；2) 影响叶栅通道主流近壁流动和气动-热性能协同的成型孔气膜射流主导因素；3) 成型孔气膜射流“强化冷却能力”与冷却结构设计“减少冷却空气系数”之间的内在关联。从而深化对于成型孔气膜射流冷却现象和规律更全面系统的认识，为高性能燃气涡轮发动机导向叶片冷却技术创新发展提供理论和应用基础。

申请课题以“高效异形”成型孔气膜射流为核心，凝练出其与叶栅通道主流的相干机制、冷却结构内部气流的共轭传热机制这两个核心的科学问题展开研究。所取的重要结果归纳如下：.1）解析了典型成型孔气膜射流在横流中的拟序涡结构发展演变特征，揭示了成型孔强化气膜冷却的内在机制及其与无压力梯度主流中强化气膜冷却的机理差异，并从气膜孔流量系数、通道流动损失、气膜冷却效率和热流衰减因子等方面对成型气膜孔冷却性能进行了综合分析和评价。.2）构建了基于CFD和径向基神经网络代理模型的多目标优化方法，获得了对应于高流量系数、高冷却效率和两者兼顾的优化参数集群，获得了小吹风比和大吹风比下的优化孔型特征；针对气膜冷却特性的相关准则模型关联度差异较大的问题，提出了一种基于支持向量机预测理论的分析模型和方法。.3）较为系统地分析了涡轮叶片吸力面和压力面侧不同的主流环境中成型孔气膜射流与主流的相干机制、进气横流效应的影响机制以及成型孔强化气膜冷却的作用效果差异，剖析了气膜射流与叶栅通道主流的掺混所诱导的叶栅气动损失；探讨了旋转效应和叶片顶部泄漏流的影响机制。.4）开展了若干高效冷却结构集成方式的研究，探究了其共轭传热机制。从气动损失、冷却效率和热应力等多个方面进行了层板冷却结构的多学科优化分析，提出了基于流向涡激励的凹腔表面射流强化方法，揭示出凹形受限空腔内部流向涡激励射流的流动特征以及强化传热效果，获得了内外流耦合下的共轭传热基本规律。.5）在模拟真实气-热条件下进行了成型气膜孔“应用”效果分析，全面评价涡轮叶片气膜孔型改变对于冷却空气引气压力、流量特性、涡轮叶片综合冷却效率、叶栅通道气动损失的影响；揭示出在有/无考虑气膜叠加效应时成型孔气膜冷却效率的差异。.项目执行期中，获得发明专利3件，发表学术论文(含已录用)37篇，其中SCI检索21篇，EI检索31篇；培养博士后1名、博士研究生10名、硕士研究生7名。