Transient investigations of teeth on rotor and teeth on stator modified labyrinth seals

Teeth-on-rotor (TOR) and teeth-on-stator (TOS) layouts are compared in this paper to explore better arrangement for different labyrinth seals. The diaphragm labyrinth seal (DLS) and hole diaphragm labyrinth seal (HDLS) are both redesigned into TOR and TOS layouts. To accurately predict the rotordynamics and leakage performance of different seals, a one-motion transient computational fluid dynamics (CFD) method based on the simplified multi-frequency transient method is proposed. A comparison of the experimental results, two-motion transient CFD method and proposed method showcase the better accuracy of the current method in rotordynamic performance prediction. The results shows the better rotordynamic characteristics of the TOS layout for different layouts and of the HDLS type seals for three labyrinth type seals. Even though, the TOR layout cannot increase the stability of the rotor system, a clear circumferential velocity reduction in the DLS and HDLS seals can be observed in both the TOS and TOR layouts. However, the changes in leakage performance for DLS and HDLS seals are different from those for traditional LSs. Unlike TOR-LS and TOR-HDLS, which exhibit relatively large increases in leakage compared with the TOS layout, TOR-DLS achieves a maximum 1.7% leakage reduction at a 15000 rpm rotation speed. A decrease in the jet flow length and increase in the turbulence kinetic energy in TOR-DLS compared with those in TOS-DLS further explain this abnormal phenomenon. •A one-motion transient computational fluid dynamics(CFD) method was verified to have the better accuracy.•Teeth-on-rotor(TOR) and teeth-on-stator(TOS) layouts were considered in traditional and modified labyrinth seals (LS).•Better stability of diaphragm labyrinth seal(DLS) and hole diaphragm labyrinth seal(HDLS) is observed in both layouts.•TOS-HDLS achieves the best leakage stoppage performance by maximum area of turbulence kinetic energy(TKE).•Only TOR-DLS can decrease 1.7% leakage of TOS-LS by decrease of axial jet and increase of TKE, in three TOR seals.