子午修型对1.5级大子午扩张涡轮端区流动传热性能影响研究

Effects of Meridional Modification on Flow and Heat Transfer Performance in End Region of 1.5-Stage Large Meridian Expansion Turbine

关键词:  子午修型  1.5级大子午扩张涡轮  端区流动  分离控制  传热特性

Key words:  Meridional modification  1.5 stage large meridian expansion turbine  Flow in the end region  Separation control  Heat transfer characteristics

摘要:

大子午扩张涡轮由于子午型线扩张度较大，因而易导致端区边界层分离及热集中，针对这个现象，采用数值模拟方法，并采用正弦曲线对1.5级大子午扩张涡轮子午型线采取了8种修型方案，研究子午修型对于端区流动传热性能的影响。计算结果表明，子午修型可以有效地控制端区的分离流动，从而影响着通道涡与脱落涡强度及位置，也影响着端壁及叶片上热负荷分布。在本文研究条件下，振幅为三分之一叶片最大厚度的前凹后凸子午型线有效地减弱了脱落涡引起的损失，进而使整体总压损失减小6.06%，并可以减弱端壁及叶片传热集中，使叶片最大热负荷减轻21%。

Abstract:

Due to the large expansion of the meridian line， the large meridian expansion turbine is easy to cause the separation and heat concentration of the boundary layer in the end region. In view of this phenomenon， the numerical simulation method is adopted， and eight modification schemes are adopted for the meridian line of a 1.5 stage large meridian expansion turbine by using the sine curve to study the effects of the meridional modification on the flow and heat transfer performance in the end region. The results show that the meridional modification can effectively control the separation flow in the end region， thus affecting the strength and position of the channel vortex and the shedding vortex， as well as the heat load distribution on the end wall and the blade. Under the condition of this study， the front concave and back convex meridional lines with the amplitude of one third of the maximum thickness of the blade can effectively reduce the loss caused by the shedding vortex， thus reducing the overall total pressure loss by 6.06%， and can reduce the heat transfer concentration of the end wall and the blade and the maximum heat load of blade is reduced by 21%.