Effects of Sealing Flow Supply Configuration with Holes on Sealing Effectiveness of Turbine Rim Seal

This paper proposes a new-designed rim seal configuration with sealing holes based on the conventional radial rim seal, and presents a numerical comparison of the sealing performance between the conventional sealing flow supply configuration and the new sealing flow supply configuration with holes at different sealing flow rates. The sealing effectiveness and unsteady flow yields at the rim seal are numerically simulated by using the URANS method and SST turbulent model from ANSYS CFX. The influence of the new sealing flow supply configuration on the sealing effectiveness at different sealing flow rates is determined. The effectiveness of different sealing flow rates in the conventional rim seal is also studied. As to the conventional rim seal, the increase in the sealing flow rate reduces the degree of gas ingestion induced by the effect of mainstream ingress at the rim clearance, while the unsteady flow characteristics are enhanced, and the number and amplitude of the low-frequency signals increase. The position of the Kelvin-Helmholtz instabilities vortex structures is left by the increased sealing flow rate, and its strength is suppressed. Compared with the conventional rim seal configuration, the new sealing flow supply configuration with holes could reduce the sealing efficiency by 5.06% at most at sealing flow distribution m₁:m₂=3:1 when C_w=2000, and improve the sealing efficiency by 11.71% at most at sealing flow distribution m₁:m₂=1:1 when C_w=7500. It shows that the lateral jet from the holes induces a larger-scale Kelvin-Helmholtz vortex structure at C_w=2000, thus the sealing efficiency in the wheel space is also reduced. However, the size of the Kelvin-Helmholtz vortex structures is significantly suppressed by the new sealing flow supply configuration at C_w=7500, which is beneficial to improving the sealing effectiveness of the conventional rim seal.