Numerical study of the characteristics of steam turbine shaft end combined seal

Abstract Effective sealing is a critical factor in ensuring the operational efficiency of steam turbines. This paper introduces a novel Spiral-Labyrinth Combined Seal (SLCS), which integrates spiral teeth with traditional labyrinth teeth to form a composite seal. By incorporating the pumping effect of spiral teeth into the Labyrinth Seal (LS) design, the leakage is significantly reduced. This study investigates the pressure drop, sealing effectiveness, and the reduction in seal length for SLCS with one to six spiral teeth under identical operating conditions and then compares these three factors with traditional LS. The results demonstrate that on the steam side, the leakage of all SLCS is lower than that of traditional LS, and the sealing performance of SLCS with three spiral teeth is the best. The pressure drop of the SLCS with three spiral teeth is 37.81% higher than that of LS at the same length, the steam leakage is 27.14% lower than that of LS, and the axial length of the R-SLCS is 9.3% shorter than that of the LS. These results validate the feasibility of the new SLCS design, providing valuable insights for optimizing steam turbine shaft-end seals.