EFFECT OF RELATIVE LOCATION OF FILM COOLING HOLE WITH INTERNAL ANGLED RIBS ON THE FILM COOLING EFFECTIVENESS OF A GAS TURBINE BLADE

Film cooling effectiveness (FCE) is strongly influenced by film cooling hole geometry, mainstream boundary condition (boundary layer thickness and turbulence intensity), and coolant injection conditions (density ratio and blowing ratio). It is also shown that the flow structure of coolant at the inlet of a cooling hole also affects film cooling performance. In this study, the inlet flow structure resulting from the rib turbulators installed in the internal channel and its effects on the film cooling effectiveness were analyzed numerically. The numerical result was also validated with experimental result obtained with the pressure sensitive paint (PSP) technique. Studies were conducted at 25 relative locations of a fan-shaped hole on the 60-degree angle ribbed channel. Furthermore, the results were compared to cases that coolant was supplied through the plenum chamber. Results showed that the relative location of the film cooling hole with respect to the angled rib significantly altered the flow structure of coolant and the distribution of FCE. Also, FCE with the angled ribbed channel generally showed low FCE compared to the case with a plenum chamber.