Abstract: In this study, the composite rim seal with the deep cavity in the static disc and the modified platform（the following abbreviation “C rim seal”）was investigated by measuring the CO2 concentration. Simultaneous-ly, an axial and an overlapping rim seal has been selected as a baseline to compare and analyze the effects of the mainstream Reynolds number (0.75×105≤Rew≤9.4×105), the sealing flow rate (flow rate ratio FR= 0.2%~2.5%), and rotating Reynolds number (1.6×105≤Reφ≤8.1×105) on the distribution of pressure and the sealing efficiency in the disc cavity. Furthermore, a corresponding numerical study was carried out to ob-tain the detailed flow characteristics. The results show that the main flow Reynolds number significantly affects the circumferential pressure distribution in the main flow channel. With the main flow Reynolds number increasing，the pressure in the main flow channel also increased and the gas ingestion intensified. The higher coolant flow rate is beneficial to improve the sealing efficiency of the disc cavity by increasing the pressure in the disc cavity, but it has less effect on the pressure at the trailing edge of the vane. An im-provement in the rotating Reynolds number increases the static pressure in the main flow channel and de-creases the sealing efficiency of the disc cavity. The flow structure of the disc cavity is changed by the set-ting of the high-radius sealing cavity, which effectively blocks the mainstream gas inside the sealing cavity and ensures that the sealing efficiency of the low-radius cavity is above 80%. The C rim seal structure not only guarantees the sealing efficiency of 85% at the low-radius disc cavity, but also improves the sealing efficiency at the high-radius sealing cavity. At a low sealing flow ratio (FR=0.2%), the sealing efficiency of the C rim seal structure is 10% higher than the other two rim seal structures.

Key words: composite rim seal, sealing efficiency, mainstream Reynolds number, rotating Reynolds number, gas ingestion