轴流涡轮与排气壳扩压段一维耦合设计研究

为探究轴流涡轮耦合排气壳扩压段的一维设计变量选取规律，提高排气壳扩压段的性能，参考现有NRCC叶栅导叶模型，采用自编程序，结合理论分析构建轴流涡轮与排气扩压段耦合的一维设计模型。详细分析耦合设计中影响扩压段的静压恢复系数以及总体性能的因素。研究结果表明：扩压段面积比、平均倾角、扩张角以及壁面摩擦系数等设计参数不仅影响扩压段的静压恢复系数，也影响涡轮的气动效率；本研究模型在面积比为3.5、平均倾角为30°、扩张角δ为5°时整体性能最优；涡轮出口气流的马赫数、叶顶泄漏流以及出口旋流对扩压段的性能有很大影响，出口半径比的增大会使得静压恢复系数降低，因此在耦合设计时应充分考虑涡轮以上参数的选择。

Research on one dimensional coupling design of axial turbine and diffuser section of exhaust casing

In order to explore the one dimensional design variable selection law of the axial turbine coupled exhaust casing diffuser section, and improve the performance of the exhaust casing diffuser section, referring to the existing NRCC cascade guide vane model, a one dimensional design model of the coupling of axial turbine and exhaust diffuser section was constructed by using self programmed program and theoretical analysis. The factors affecting the static pressure recovery coefficient and overall performance of the diffuser section in the coupling design were analyzed in detail. The results show that the area ratio, average inclination angle, divergence angle and wall friction coefficient in the design parameters of the diffuser section not only affect the static pressure recovery coefficient of the diffuser section, but also affect the aerodynamic efficiency of the turbine; for the research model in this paper, the overall performance is best when the area ratio is 3.5, the average inclination angle is 30°, and the divergence angle is 5°; however, the Mach number, blade tip leakage flow and outlet swirl of the turbine outlet gas flow have a great influence on the performance of the diffuser section, and the increase of the outlet radius ratio reduces the static pressure recovery coefficient, so the selection of the above parameters of the turbine should be fully considered when coupling the design.