In this paper we present a mixed thermofluidodynamical and mechanical approach to the life analysis of thermally-loaded components, and apply it to a combustor liner.
When studying this class of problems, we are mostly concerned with a) the material parameter identification and b) the load history definition. While testing may alleviate the need for point a), we must put a lot of care in b), since the distribution of temperature (i.e., the thermal gradient) inside components and their load history are very difficult to measure accurately.
To face these kind of problems we take as input the results of thermofluidodynamical calculations made with the FLUENT computer code at the ENEL (Italian Electric Power Company) Research Centre of Pisa to simulate the experimental behaviour of a combustor liner under different load conditions (phase 1). The output data have been processed in order to use them with the MARC Finite Element (F.E.) code transient thermal analysis (phase 2). Finally we took the MARC thermal simulation results as input to the mechanical analysis (phase 3). To interface the FLUENT and MARC codes, we developed a numerical program to map grid data (FLUENT) to the Finite Element mesh (MARC) by means of an interpolation algorithm.
This way, once we got a likely temperature distribution inside the component by means of the first step, we were able to follow the load history during the second and the third phases.
By this approach we were able to a) simulate the evolution of the combustor liner under cyclic thermal loads, b) identify the critical areas and c) make estimations of the life of the component under these loads.