Abstract
To obtain high gas turbine efficiency, a film cooling hole is introduced to prevent the destruction of thermal barrier coating systems (TBCs) due to hot gases. Furthermore, environmental calcium-magnesium-aluminum-silicate (CMAS) particulates plug the film cooling hole and infiltrate the TBCs to form a CMAS-rich layer, which results in phase transformations and significant modifications in the thermomechanical properties that impact the TBCs during cooling. This study aimed to establish a three-dimensional thermo-fluid-solid coupling TBCs model with film cooling holes and CMAS infiltration to analyze the temperature and residual stress distribution via simulations. For the interfacial stress around the cooling hole at the TC/BC interface, the film cooling holes alleviated the interfacial residual stress by 60% due to the reduction in temperature by 40%. In addition, CMAS infiltration intensified the interfacial residual stress via phase transformation. As a result of the influence of larger penetration depths and expansion rates of phase transformation, a significant increase in residual stress was observed. At the beginning of CMAS infiltration, the interfacial stress would be more dominated by the effect of infiltration depth. In addition, the failure due to interfacial normal and tangential stresses was more likely to be found at the infiltration zone near the cooling hole.
Highlights
Innovations in gas turbines have been widely implemented in aviation systems over the past few decades
This study investigated the evolution of interfacial residual stress near a round cooling hole with a 30◦ inclined angle caused by CMAS infiltration during the cooling period
The presence of film cooling holes was used to increase the efficiency of the gas turbines
Summary
Innovations in gas turbines have been widely implemented in aviation systems over the past few decades. Turbine blade components generally operate at elevated temperatures and are subjected to high thermal loads. TBCs are multilayer systems that include a top coat (TC) layer, a bond coat (BC) layer, a thermally grown oxide layer, and a substrate. It helps protect the substrate from hot corrosion and thermal loads owing to high temperature gradients. A film cooling hole is introduced in TBCs [3]. A coolant is introduced through the film cooling hole into the surface of the airfoil to decrease the temperature [4]. In addition to the increase in turbine efficiency, the presence of film cooling holes protects the TBCs from destruction caused by hot gases
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