Pressure Distortion Effects on Rim Seal Performance in a Linear Cascade

Abstract

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.