机匣梯形篦齿对带冠涡轮气动性能的影响

Effects of the trapezoid labyrinth on the casing on the aerodynamic performance of the shrouded turbine

应用数值方法对某两级带冠涡轮的流场进行模拟。基于原叶冠结构,增加叶顶间隙设计值,减小叶冠上的篦齿与机匣发生磨碰的可能性,并在机匣内壁设置梯形篦齿与原叶冠上的篦齿形成交错型篦齿结构进行密封。研究结果表明:机匣梯形篦齿的设计改变了叶冠顶部泄漏流流场结构,提高了叶冠的密封性能,改善了涡轮的气动性能;不同工况条件下交错型篦齿比原结构的涡轮效率提高了0.5%左右。

A two-stage turbine with shroud is studied in this paper through a numerical simulation pro- gram, and the designed value of the tip clearance is improved based on the original labyrinth structure. The proposed design could reduce the conflict possibility of the labyrinth and the casing. Meanwhile, the stag- gered labyrinth formed by the trapezoid labyrinth on the casing and the original labyrinth on the blade shroud are applied as seals. The simulation results show that the flow structure on the top of shroud is changed, the sealing performance is accordingly improved, and the aerodynamic performance of the turbine is enhanced with the trapezoid labyrinth. Moreover, the staggered labyrinth improves the turbine efficiency by 0.5% when compared with that for the original labyrinth.