Effects of Row Trench Holes Geometries on an Endwall Cooling
Keywords:gas turbine, film-cooling, cylindrical hole, trench hole
Gas turbine industries try to extend the gas turbine engine performance. By using the well-known Bryton cycle, the combustor outlet temperature must be increased to have higher efficiencies. However, the turbine inlet temperature increment creates harsh environment for the downstream components of the combustor. This requires designing an efficient cooling technique in this area. In the traditional cooling system, the increase in blowing ratio enhances cooling effectiveness. But, the coolant does not well attach on the surface at higher blowing ratios. This necessitates restructuring the cooling holes. A useful way can be trenching cooling holes at the combustor end wall surface and the alignment of row trenched holes; however, this has not been seriously considered as a solution up to the present time. The major effects of cylindrical and row trenched cooling holes with alignment angle of 0, +60 and 90 degrees at blowing ration, BR=3.18 on the effectiveness of film cooling near the combustor end wall surface is a subject to study in detail. In the current study, researchers used a FLUENT package 6.2.26 to simulate a 3-D model of a Pratt and Whitney gas turbine engine. In this research, a RANS model was used to analyses the flow behaviour on the passageways of internal cooling. In the combustor simulator, the dilution jets and cooling flow staggered in the streamwise direction and aligned in the spanwise direction as well. In comparison with the baseline case of cooling holes, the application of row trenched hole near the endwall surface increased the effectiveness of film cooling from 75% to 100% for different trench cases.