Low-Order Modeling to Investigate Clusters of ITA Modes in Annular Combustors

Hot gas ingestions into a turbine rim cavity cause severe damages to a turbine disk. Cooling flow prevents hot gas from ingesting through rim seals. Although developed rim seal designs mitigate the consumed cooling flow rate, the partial ingestion occurs yet. The main reason for the ingestion is not only asymmetric of the pressure distribution of throughflow but unsteady flow by rotating blade. Understanding the unsteady flow helps to design advanced rim seals. The objective of this study is to gain insight into unsteady flow in a turbine rim cavity. Unsteady Reynolds averaged Navier-Stokes (URANS) simulation was conducted. The model was verified through the 1.5 stage turbine rim seal test rig designed based on the aero-engine gas turbine. Flow structure and mixing phenomena were analyzed using a tracer gas method. At the interface between the turbine rim cavity and hot gas and the meridian plane of 0%, 30%, and 60% circumferential direction from the trailing edge, the sealing effectiveness variation over time was confirmed. Compared with a steady-state simulation, the time-dependent flow of the turbine rim cavity revealed prominently. The unsteady flow pattern affects the local sealing effectiveness highly. With increase rotational Reynolds number, the variation of sealing effectiveness was also observed. Therefore, for improving the rim seal design, the complex flow should be considered.

(Acknowledgement: This work was supported by the Industrial Strategic Technology Development Program (No.20002700) funded By the Ministry of Trade, Industry & Energy(MOTIE, Korea), This work was supported by the Human Resources Development program (No.20174030201720) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Trade, Industry and Energy. This work was partially supported by the Hanwha Aerospace.)