Numerical Study of the Interaction between the Sealing Flow Rate and the Main Flow in a Gas Turbine Stage

This paper focuses on the interaction process between the main and cavity flows in a gas turbine. To this purpose, Reynolds-Averaged Navier-Stokes (RANS) simulations are conducted on the full stage with including the cavity system. Different sealing flow rates injected into the cavity are simulated to study different operating conditions. The study employs a robust computational fluid dynamics (CFD) framework (Cadence) to perform the RANS simulations, leveraging on turbulence models to capture the complex interactions due to the cavity. The aim is to validate the numerical approach in order to provide an accurate flow field within the cavity. To this purpose, the numerical model is compared against experimental data and a good agreement is found. The RANS simulations are validated with experimental data and they allow us to study the time-mean flow field and to calculate an estimate of the time-mean performances of the machine. The increase in the mass flow rate injected into the cavity leads to a local increase in losses near the hub and also to a local variation of the flow angle, with the effect of reducing the aerodynamic efficiency of the downstream blade. This study provides additional data about the main channel-cavity interaction phenomena that may be useful to designers to improve gas turbine performance.