Heat transfer analysis of damaged shrouded high-pressure turbine rotor blades

Authors

Mario Carta - Unversity of Cagliari, Italy
Shahrokh Shahpar - Rolls-Royce Plc
Tiziano Ghisu - Unversity of Cagliari, Italy

Abstract

Due to the increasingly high turbine inlet temperatures, heat transfer analysis is now more than ever a vital aspect of the operation of the High-Pressure Turbine (HPT) rotor blades of a modern Jet Engine. This work constitutes the second part of an analysis on the aero-thermal effects of in-service damage, where the first part focused on the aerodynamics and the parametrization of shape deviation from nominal, highlighting the importance of the intra-platform shroud gap for the high-pressure stage aerodynamic efficiency. The present study aims to understand how shape deviation and in-service deterioration affect the heat exchange patterns on the rotor blade. The rotor geometries used for this analysis are represented by a set of 120 high-resolution structured light scans (GOM) of blades with different number of in-service hours. An automatic meshing technique is employed to generate high-resolution unstructured meshes directly on the scanned rotor geometries, which allowed to capture all the surface features with high fidelity. Steady-state 3D RANS flow simulations with the k-ω turbulence model are conducted on a one-and-a-half stage computational domain where the 120 different high-pressure rotor geometries are used. The objective of this analysis is to quantify the effect of damage on surface heat flux. To do this, the distribution of Heat Transfer Coefficient (HTC) is calculated for each blade, through the use of a novel, low-cost methodology. Then, a correlation study is conducted between the present HTC results and the parametrized shape deviation data obtained in the previous part of this analysis. The thermal implications of the uncertainty existing on the inlet temperature distribution are also studied.