大子午扩张涡轮端区的流动传热及端区正弯效果的数值研究

Numerical Study of Flow-Heat Transfer and End-ZonePositive Tangential Curve Technology of LargeMeridional Expansion Turbine

关键词:  大子午扩张涡轮  端区流动  传热特性  数值模拟  端区正弯

Key words:  Large meridional expansion turbine  Flow at the end wall  Heat transfer characteristics  Numerical simulation  End-zone positive tangential curve

摘要:

为了研究大子午扩张涡轮端区流动和传热特性，并研究叶片端区正弯技术在大子午扩张涡轮中的气动和传热效果，对某大子午扩张涡轮静叶进行数值模拟。运用SST湍流模型精确捕捉流动结构，并进行了气动和传热预测的有效性实验验证。通过分析结果，对大子午扩张涡轮端区流动和传热特性以及两者相互影响关系进行了深入研究，分析了端区正弯技术在重组大子午扩张涡轮端区流动以及合理分布热负荷的应用效果。结果表明：大子午扩张端壁导致涡轮端壁附面层的强烈分离，通道涡分离点提前约15%，高传热区受马蹄涡和通道涡的强烈影响；端区正弯有效地改善了大子午扩张静叶端壁的附面层分离，减小前缘的热负荷25%，提高涡轮的气热性能。

Abstract:

In order to study the flow and heat transfer characteristics of the large meridional expansion turbine at the end-zone and the effect of end-zone positive tangential curve technology， numerical simulation of a large meridional expansion turbine vane was performed. The SST turbulence model is used to capture the flow structure accurately. The validity verification of aerodynamic and heat transfer prediction is carried out. Through simulation calculation， both the flow and heat transfer characteristics and the influence of each other were studied at the end-zone of the large meridional expansion turbine. End-zone positive tangential curve technology was analysed for the application effect of recombinant large meridional expansion turbine end-zone flow and reasonable distribution heat load. It can be concluded that the large meridional expansion end wall results in the strong separation of the boundary layer of the turbine end wall， and the separation point of the passage vortex is about 15% in advance. The high heat transfer area is strongly influenced by horseshoe vortex and passage vortex. The end-zone positive tangential curve technology can effectively improve the separation of the boundary layer， reduce the heat load of the front edge by 25%， and improve the gas thermal performance of the turbine.