LES Analysis of a High-Pressure Turbine Rotating Blade Flow Including Purge and Tip Flows

Abstract A careful introduction of coolant airflows, which create the film protecting the turbine blade, is critical for a more fuel-efficient and environmentally friendly jet engine. Accurate prediction of streams mixing with the cooling airflows is of great interest for achieving a better design of a jet engine. The main objective of this paper is to numerically investigate the rate of heat transfer in a high-pressure turbine (HPT) rotor passage with purge flow at the hub using a large eddy simulation (LES.) An in-house CFD solver, Glenn-HT from the NASA Glenn Research Center was utilized. The three-dimensional blade and the conditions are those of the Penn State University START rotating rig. A high-quality 125 million cell structured grid, which adequately resolves the high-Reynolds number flow (Re∼350,000) and the complex secondary flow structures, was constructed. To evaluate the adiabatic wall temperature, two LES simulations with different isothermal wall temperatures were carried out. This method is more robust especially when cooling air injections at the blade surface need to be considered. Our numerical simulations were able to capture a very accurate representation of three-dimensional unsteady flow structures near the tip as well as the secondary flow originating from the purge. Several distinct high heat transfer areas were identified. In addition, temporal “energy separation” in the high vorticity level regions was observed, which has not been reported before.