Effect of relative location of film cooling hole with internal angled ribs on the film cooling effectiveness of a gas turbine blade

• The relative location of film cooling holes with angled ribs significantly affects coolant flow structure and film cooling effectiveness (FCE). • Numerical and experimental analyses revealed up to 58% variation in FCE depending on streamwise and lateral hole positions. • The film cooling hole located between ribs and near sidewalls showed asymmetric flow and lower FCE due to intensified flow deflection and vorticity. • Compared to plenum chamber supply, internal ribbed channel cases reduced FCE by up to 26 %, highlighting the importance of realistic internal flow modeling. Film cooling effectiveness (FCE) is strongly influenced by film cooling hole geometry, mainstream boundary conditions, and coolant injection conditions. It has also been shown that the flow structure of coolant at the inlet of a cooling hole 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 FCE were analyzed numerically. The numerical result was 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 in which 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. The angled ribbed channel generally showed low FCE compared to the case with a plenum chamber.