Numerical research on effect of dislocated turbine rims on hot gas ingestion

Abstract

The flow characteristics in the rim clearances of turbines are sensitive to the turbine rim structures. From this standpoint, rotor–stator cavity models with dislocated clearances are proposed in this study to reveal the effect of dislocated turbine rim lips on hot gas ingestion and the clearance flow characteristics. The results show that the rim clearance flow is unstable, and Kelvin–Helmholtz vortices are induced by the relatively large difference in circumferential velocity of the flow fields inside and outside the rim seal. Moreover, the dislocated turbine rim lips decrease the effectiveness of the rim seal. Ultimately, the responses of the flow characteristics to the dislocated rims are determined to be primarily reflected in the effect of the forward or backward step flow on the Kelvin–Helmholtz vortices in turbine rims.