Heat Transfer in Turbine Hub Cavities Adjacent to the Main Gas Path

Reliable means of predicting heat transfer in cavities adjacent to the main gas path are increasingly being sought by engineers involved in the design of gas turbines. In this paper, an interim summary of the results of a five-year research program sponsored by the European Union (EU) and several leading gas turbine manufacturers and universities will be presented. Extensive use is made of computational fluid dynamics (CFD) and finite element (FE) modeling techniques to understand the thermo-mechanical behavior of a turbine stator well cavity, including the interaction of cooling air supply with the main annulus gas. The objective of the study has been to provide a means of optimizing the design of such cavities for maintaining a safe environment for critical parts, such as disc rims and blade fixings, while maximizing the turbine efficiency and minimizing the fuel burn and emissions penalties associated with the secondary airflow system. The modeling methods employed have been validated against data gathered from a dedicated two-stage turbine rig running at engine representative conditions. Extensive measurements are available for a range of flow conditions and alternative cooling arrangements. The analysis method has been used to inform a design change, which is also to be tested. Comparisons are provided between the predictions and measurements of the turbine stator well component temperature.