A Novel Design of Rim Sealing Flow for Improving Sealing Effectiveness

AbstractRim seal structures and sealing flows are essential in aero engines for preventing hot gas ingestion from mainstream to turbine disk cavities. A novel design method of rim sealing flow path based on auxiliary sealing holes and sealing air re-distributions has been proved to improve sealing effectiveness. The present paper uses this method to re-design the axial rim sealing flow in a high-pressure turbine front cavity in an engine turbine. The incidence angle of the auxiliary sealing air has been proved to have a significant influence on sealing performance. Three different incidence angles, 0-deg, 35-deg, and 70-deg, with the maximum angle close to the vane exit flow angle, are investigated using unsteady computational fluid dynamics methods validated by experimental data. Sealing effectiveness, swirl ratio, unsteady flow structures in both rim clearance and wheel space cavity are considered. The auxiliary sealing air with a swirl in the circumferential direction is proved to improve and uniform swirl ratio and suppress flow instabilities. This results in a reduction in hot gas ingestion and a considerable improvement in sealing effectiveness. The mechanisms of improving sealing effectiveness using this novel method are explained. The conclusions may support the understanding of the complex flow mechanisms near the rim seal, provide references for the design of this novel structure and give possibilities to improve rim seal performance and engine efficiency.