【作者】 林立；

【导师】 蒋洪德；

【作者基本信息】 清华大学 ， 动力工程及工程热物理， 2013， 博士

【摘要】 随着燃气轮机技术的发展，透平前温不断升高，二次空气系统所需冷气量不断增加，由于这部分气体做功能力有限，因此通过优化设计以减少冷气用量是提高燃机性能的有效途径。二次空气系统中包含的结构形式多样，流动传热现象复杂多变，掌握其中的机理是进行优化设计的重要前提。本文研究以转静系盘腔为主，其多位于轮缘密封以及供给转子冷气的通路中，腔内的流动传热问题不仅关系到燃机的稳定运行也是整机优化设计的重要部分。本文首先对某重型燃机的二次空气系统进行一维网络分析，确定了各处冷气分配和压力分布，总结了透平中各盘腔实际工况对应的无量纲参数条件；并从轴向力和热分析的角度阐述了盘腔内流动传热计算对于重型燃机设计的重要性。为了对盘腔内流动传热机理进行实验研究，本文设计搭建了二次空气系统单元机理实验台。参数设计考虑了重型燃机二次空气系统的特点和盘腔基础研究的需求；结构方案考虑了对多种盘腔结构的研究需求，进行统一设计；实验台的测量系统包含传统的压力、流量、温度测量以及热敏液晶瞬态实验技术的应用。对转静系盘腔流动问题进行实验和数值研究：从源区边界和动盘面边界层流量两个方面对中心进气转静腔的一维模型进行修正，改进了其对腔内流动的模拟；从角动量和盘面转矩的角度对预旋进气转静腔进行分析，导出影响腔内流动的两个无量纲数为修正湍流流动参数λ’t与来流雷诺数Rep，并总结了其对角动量系数cdisk的影响规律。通过分析指出，对于真实转静盘腔中动盘面传热的估计可转化为对两类理想情况的研究。对于第一类理想情况（非耦合），采用热敏液晶技术进行实验研究，验证了雷诺相似分析方法在该类问题上的适用性；对于第二类理想情况（气热耦合），研究以数值模拟为基础，结合轮盘一维导热分析，提出了简化模型，用以描述耦合情况下冷气量变化对动盘面换热的影响。根据两类理想情况的结果，可确定实际燃机中转静盘腔动盘面传热系数所处的范围。本文采用实验和数值模拟方法对转静系盘腔内的流动传热机理进行了研究，并将结果整理为一维形式，可应用于工程设计，以提高二次空气系统网络分析中对转静系盘腔的模拟能力。更多还原

【Abstract】 With the development of gas turbine, the turbine inlet temperature keepsincreasing, and so does the amount of secondary air. As the coolant doesn’tmake much contribution to output power, optimisations which will reduce theamount of coolant are effective ways to improve the gas turbine efficiency. Theactual structure of secondary air system(SAS) is very complicated, and so arethe flow and heat transfer phenomena in it. An essential precondition ofoptimization would be the understanding of the mechanism. This paper focusedon the research of rotor-stator cavities, which usually exist with rim seals andthe network in which coolant is provided to rotor. The flow and heat transferwithin are not only related to the stability of engine but also important parts ofoptimization of gas turbine.1D analysis was carried on the flow network of SAS of some industrial gasturbine. The distribution of coolant flow rate and pressure is determined. Thenondimensional numbers of cavity flow in industrial gas turbine are summarized.The importance of accurate calculation of flow and heat transfer in cavities isexpounded in view of thrust and heat transfer analysis of the whole engine.In order to carry experimental research on flow and heat transfer in cavities,the "secondary air system unit test rig" was designed and built up. Theparameter design takes into account the features of SAS of industrial gas turbineand needs of fundamental research in cavity flow. The structure design takesinto account different types of cavities. The measurement system includes notonly normal techniques for pressure, flow rate and temperature measurement,but also the application of thermochromic liquid crystal(TLC) for transient heattransfer experiments.The flow dynamics in rotor-stator cavities were studied both numericallyand experimentally. The1D model of flow in rotor-stator cavity with centralinlet is corrected to improve the performance. Corrections are made to thecalculation of source region boundary and mass flow rate entrained by disk, based on the numerical results. As to rotor-stator cavity with pre-swirl inlet, twonondimensional numbers, corrected turbulent flow parameter λ’tand pre-swirlinlet Reynolds number Rep, are pointed out to be the dominant factors that affectthe flow in cavity, in view of angular momentum and torque. And the effects ofλ’tand Repon angular momenturm coefficient cdiskare explored.The estimation of heat transfer of rotating disk in rotor-stator cavities inreal engines can be realized by studying two types of ideal cases. As for the firsttype ideal case(non-conjugate), the experimental results by TLC proved that theReynolds analogy is adequate for this type of problem. As for the second typeideal case(conjugate heat transfer), a simplified model is brought out based onthe conjugate numerical simulation results together with1D conduction analysisof turbine disk, to describe the effect of coolant flow rate on heat transfer ofrotating disk. According to the results of the two types of ideal cases, the rangeof heat transfer coefficients of rotating disk in rotor-stator cavity in real enginecan be determined.This paper carried both experimental and numerical studies on flow andheat transfer mechanism in rotor-stator cavities. The results are presented in onedimensional form, which can be used in industrial design to improve thecapacity of modelling rotor-stator cavity in network analysis of SAS.更多还原