Numerical Analysis of Jet Impingement Heat Transfer for Gas Turbine Rotor Blades

Jet impingement is widely adopted for turbine blade cooling due to the higher heat transfer rate compared to conventional forced convection solutions. Although RANS turbulence modeling is suitable for industrial scale applications, it lacks of accuracy when dealing with jet impingement heat transfer. The present study aims at comparing the aerodynamics and heat transfer of a leading edge cooling cavity for rotating turbine blade applications. The cooling cavity consists of a single array of jets impinging on a leading edge channel provided with three arrays of cooling holes. Different CFD approaches are proposed: RANS/URANS simulations and high-fidelity VLES simulations based on Lattice Boltzmann Methods (LBM). In all cases, commercial CFD solvers are used: ANSYS Fluent and SIMULIA PowerFLOW®, respectively. Despite similar averaged simulation results, substantial local differences emerge when comparing the different models against each other. With the LBM approach, the normalized Nusselt evolution is flattened with respect to RANS simulations. The latter provides higher amplitude fluctuations in both the radial and span-wise directions. The results indicate that unsteady approach is more reliable in capturing jet flow behavior within the cavity and heat transfer performance at the leading edge wall, under the effects of rotation.