Heat transfer in turbine hub cavities adjacent to the main gas path

Reliablemeans of predicting heat transfer in cavities adjacent to themain gas path are increasingly being sought by engineers involvedin the design of gas turbines. In this paper anup-dated analysis of the interim results from an extended researchprogramme, MAGPI, sponsored by the EU and several leading gasturbine manufactures and universities, will be presented. Extensive use ismade of CFD and FE modelling techniques to understand thethermo-mechanical behaviour and convective heat transfer of a turbine statorwell cavity, including the interaction of cooling air supply withthe main annulus gas. It is also important to establishthe hot running seal clearances for a full understanding ofthe cooling flow distribution and heat transfer in the cavity.The objective of the study has been to provide ameans of optimising the design of such cavities (see Figure1) for maintaining a safe environment for critical parts, suchas disc rims and blade fixings, whilst maximising the turbineefficiency by means of reducing the fuel burn and emissionspenalties associated with the secondary airflow system. The modelling methodsemployed have been validated against data gathered from a dedicatedtwo-stage turbine rig, running at engine representative conditions. Extensive measurementsare available for a range of flow conditions and alternativecooling arrangements. The analysis method has been used to informa design change which will be tested in a secondtest phase. Data from this test will also be usedto further benchmark the analysis method. Comparisons are provided betweenthe predictions and measurements from the original configuration, turbine statorwell component temperature survey, including the use of a coupledanalysis technique between FE and CFD solutions