Thermal State Analysis of Industrial Gas Turbine Blades

Abstract

The correct prediction GT hot components metal temperatures is decisive for lifetime assessments including predictions of fatigue, creep, oxidation, and corrosion. For the lifetime assessments of new components (at design phase) the thermal analysis is usually based on empirical correlations and simplified calculation models. To mitigate the uncertainties of the models and boundary conditions broad safety margins are included in the calculations. Therefore, the lifetime predictions at design phase can deviate significantly from the real achievable life. Based on the results of testing, prototype and field experience the predictions can be improved by corrections of models. This paper describes the procedure for thermal state predictions of industrial turbine blades and calibration procedure based on tests and field experience. The calibration procedure comprises: • Analysis of field experience, including temperature mapping. • Correction of thermal design models. • Recalculation of thermal state for different conditions, and re -evaluation of lifetime. Such approach allows to mitigate the limited accuracy of today’s design technology and/or allows to develop the improvements measures (e.g. for service interval extension). The paper describes the separate models implemented in this approach, and provides the example of industrial GT blading analysis. On basis of this analysis the measures for service interval extension have been developed.