DES study of the unsteady flow and film cooling at trailing edge cutback with various internal rib configurations

Abstract

Cutback film cooling is widely employed to provide thermal protection for advanced turbine blade trailing edges (TE). In this study, Detached Eddy Simulation is used to investigate the unsteady flow and film cooling characteristics on trailing edge cutbacks with different internal rib configurations, especially the model with latticework ducts. Two blowing ratios (M = 0.2 and 1.25) are considered to evaluate the effect of the coolant jet. The results indicate that the rib configurations significantly change the distribution of film cooling efficiency on the cutback wall. At M = 0.2, TE cutback with a single rib array exhibits the lowest efficiency among all the investigated cases. The cutback with latticework ducts maintains a relatively higher efficiency on both sides of the domain due to the effect of the deflected swirling coolant jets. Flow details confirm that the movement of coolant and mainstream is closely related to anti-counter/counter rotating vortex pairs for the model with rib arrays and pin fin arrays. Furthermore, the deflected swirling jets in the latticework ducts lead to a large-scale rotating streamwise vortex system in the cutback region, which influences the dynamic mixing process. Finally, there is a positive correlation between flow loss and flow blockage in the uniform slot.