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

A two-stage turbine with shroud is studied in this paper through a numerical simulation program, 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 staggered 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.