EFFECTS OF COOLING CONFIGURATIONS ON THE AEROTHERMAL PERFORMANCE OF A TURBINE ENDWALL WITH JET IMPINGEMENT AND FILM COOLING

With the rapid increase of turbine inlet temperature and the application of premixed combustion, turbine components, particularly the turbine endwall, works in extremely harsh environment and must be effectively cooled to ensure the component durability. Recently, new cooling schemes that employ both external film cooling and internal jet impingement cooling have drawn much attention due to their extraordinary performance. In this study, a numerical model of turbine endwall with jet impingement and film cooling was established and validated against the experimental results. To investigate the effects of geometric parameters related with this cooling scheme, four parameters including impingement hole-to-hole pitch P-i, impingement hole diameter D-i, impingement channel height H, film hole diamete D-f, were selected to adjust within a reasonable range. The uniform design method was used to collect a database that represented the design space formed by the four parameters. Performance criterions including area-averaged overall cooling effectiveness, standard deviation of overall cooling effectiveness, total pressure drop coeffcient of the cooling system were evaluated through CFD calculations. To explore and exploit the design space as much as possible, a Kriging surrogate model was built from the database. Analysis of variance (ANOVA) was conducted based upon the surrogate model to investigate the main effect of each parameter and the correlation between parameters. Finally, based upon the knowledge obtained from ANOVA, typical designs were selected from the database which yielded either best or poorest performances. Through detailed analysis of flow and heat transfer mechanisms of these typical designs, the influence of each parameter was illustrated clearly and suggestions for the design of similar cooling schemes were drawn.