Numerical Investigation of Heat Transfer and Purge Flow Mechanisms in a Turbine Cascade with Bottom Platform Cavity

The turbine of an aeroengine is exposed to a high-temperature mainstream, making sufficiently dimensioned cooling and sealing for all components involved indispensable. Balanced thermal safety and overall efficiency demand a better understanding of the aerodynamic and thermal behavior. This study focuses on the cavity at the bottom of the rotor platform, which is connected to the main flow through the midpassage gap between two adjacent blades mounted on the turbine disk. A numerical approach has been conducted to obtain the flow mechanism, sealing effectiveness and heat transfer characteristic for various purge flow rates and midpassage gap clearances. The results of the steady-state simulations show variations in the flow pattern and in the thermal load parameters, such as the adiabatic cooling effectiveness or the heat transfer coefficient. The distinct sensitivity highlights the necessity of a subtle adjustment of those parameters, to prevent critical hot spots endangering thermal safety. © 2024 Marco Hahn, Jonas Schmid and Hans-Jörg Bauer.