Fluid Dynamics of Turbine Rim Seal Structures: A Physical Interpretation Using URANS

作者：Giove De Cosmo, James A. Scobie, Gary D. Lock, Carl M. Sangan, Mauro Carnevale · 发表于：Journal of Engineering for Gas Turbines and Power · 年份：2022 · DOI：10.1115/1.4055752 · 被引用次数：10 · 研究领域：Turbomachinery Performance and Optimization、Tribology and Lubrication Engineering、Heat Transfer Mechanisms

Abstract Unsteady Reynolds-averaged Navier–Stokes modeling (URANS) is a valuable and cost-effective tool for computational fluid dynamics (CFD), including the investigation of mainstream–cavity interaction in turbines. Despite the gap in accuracy with higher order CFD methodologies, URANS is among the few simulation strategies of industrial interest suitable for predicting ingress/egress over a wide range of conditions. This paper presents a numerical study of the flow-field in the upstream double-radial seal of a 1.5 stage turbine. Various configurations are tested, including nonpurged and purged conditions. Rigor of the approach is ensured by a set of sensitivity analyses, allowing the delineation of a best practice on the use of URANS in rim seal simulations: this includes an assessment of the effects of sector size, cavity domain size, and blade count. Time-averaged and time-resolved flow predictions capture coherent structures in the rim gap. An association between the three-dimensional (3D) morphology of these structures and different ingress/egress mechanisms is proposed. Regions of enhanced radial activity are identified to correspond with the blade leading edges. A frequency analysis of unsteady pressure signals probed in the rim gap leads to a calculation of the structure number and speed. The structures are synchronous with the disk rotation for nonpurged cases but rotate at slower speed when purge is introduced. The relative number of blades and vanes directly inf...