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 four-year research programme sponsored by the EU and several leading gas turbine manufactures and universities will be presented. Extensive use is made of CFD and FE modelling techniques to understand the thermo-mechanical behaviour 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 optimising the design of such cavities for maintaining a safe environment for critical parts, such as disc rims and blade fixings, whilst maximising the turbine efficiency, and minimising the fuel burn and emissions penalties associated with the secondary airflow system. The modelling 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.