Rim seals in the turbine section of gas turbine engines aim to reduce the amount of purge air required to prevent the ingress of hot mainstream gas into the under-platform space. A stationary, linear cascade was designed, built, and benchmarked to study the effect of the interaction between the pressure fields from an upstream vane row and downstream blade row on hot gas ingress for engine-realistic rim seal geometries. The pressure field of the downstream blade row was modeled using a bluff body designed to produce the pressure distortion of a moving blade. Sealing effectiveness data for the baseline seal indicated that there was little to no ingress with a purge rate greater than 1% of the main gas path flow. Adiabatic endwall effectiveness data downstream in the trench between the vane and blade showed a high degree of mixing. Extending the seal feature associated with the vane endwall indicated better sealing than the baseline design. Steady computational predictions were found to overpredict the sealing effectiveness due to underpredicted mixing in the trench.

Rim seals are used to prevent the ingress of hot gas into the cavities beneath turbine platforms. As these cavities are not actively cooled, high-pressure air, known as purge flow, is taken from the compressor and introduced beneath the platform to prevent hot gas from penetrating through the gaps between stationary and rotating hardware. Improving the rim-seal geometry however, is made difficult by a lack of understanding of the salient fluid mechanics associated with this region. This study investigates both the impact of a vane-induced static pressure distortion as well as the influence of the pressure distortion of a downstream blade row on an engine-relevant rim seal in a stationary, linear cascade. Vane alterations resulted in minimal change to rim seal performance; however, adding the pressure distortion of a downstream blade row was found to disturb the trench flow resulting in poorer performance of the seal.