SEALING FLOW RATE EFFECTS ON UNSTEADY LOSS PRODUCTION IN A LOW PRESSURE TURBINE STAGE

Description

Efforts to increase efficiency in aircraft and power generation turbines have raised turbine inlet temperatures (TIT), necessitating advanced cooling technologies to maintain material integrity. Preventing the ingestion of hot gases into components not suited for high temperatures, like stator/rotor cavity disks, is crucial. Current gas turbine performance strategies focus on minimizing leakage and optimizing sealing systems. Notably, losses from main flow and cavity interactions are prominent in stator/rotor systems. Using Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations, this study explores the unsteady interaction in a low-pressure turbine's stator/rotor cavity. Numerical simulations of the University of Genova's cavity rig are validated against experimental results. The investigation examines stator/rotor interaction effects, including wake ingestion from upstream rotor bars and the blocking impact of downstream rotor bars on cavity sealing. Varied cooling air injection rates in multiple calculations reveal insights into stage efficiency and cavity leakage. Emphasis is on unsteady loss mechanisms downstream of the vane row and in the region where the cavity flow is reintroduced in the main channel, providing a better understanding of losses influenced by cooling flow rates. The analysis of the loss amount along the axial direction demonstrates that losses generated in the vane row are increased prior to entering into the downstream rotor bars, due to cavity main flow interaction. This provide useful information about the production of losses due to sealing flow rate.

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