Many Alstom heavy-duty gas turbines with a silo combustor are in service and moreover undergoing upgrades for performance augmentation, lifetime extension, and emission reduction. The combustor liners, which are exposed to high gas temperatures, may require design tuning for these upgrades, and therefore reliable simulation of their behavior is of utmost importance. This paper focuses on a case study of transient behavior of the Hot Gas Casing, a transition liner between compressor, turbine and silo combustor. Following a three-dimensional thermal assessment based on computational fluid dynamics, detailed structural analysis is done to identify the drivers behind different types of Hot Gas Casing deformation, observed after upgraded combustor introduction. Thermal Barrier Coating application is proposed to reduce Hot Gas Casing bending. The solution was confirmed analytically and successfully introduced in the field. Good correlation of field findings and finite element prediction was found. It is shown that only a combined effect of thermal deformation, cyclic loading and creep may explain the observed behavior of the part. A detailed design sensitivity study is performed, comparing different approaches to deformation reduction: application of ribs, corrugations and wall thickness increase. The best solution in terms of manufacturability and its impact on part deformation is chosen. It is found that wall corrugation does not provide the desired effect due to the nature of part deformation.
