Analysis of upstream, double-row, cylindrical holes on primary and secondary effects of endwall flow and film cooling

Flow features and film cooling performance of five configurations of double-row, cylindrical holes, upstream of an E3 vane, in a linear cascade are numerically investigated. This simulation is completed using a verified turbulence model at four blowing ratios (M = 0.5, 1.0, 1.5, 2.0). The first three configurations have two rows of cylindrical holes, each row with the same compound angle (β=-45°, 0° or 45°), while the other two have two rows with opposite compound angles (β=-45°, 45° and β=45°, -45°), which are also referred to as double-jet film cooling (DJFC) holes. The primary effects on the downstream endwall and the secondary effects on the nearby airfoil of the cooled passage are analyzed and discussed in detail. Results show that at low blowing ratios the movement of the coolant is denominated by the interaction between the jets and vortices resulting in similar film coverage on both the endwall and airfoil. The effect of vortices is reduced at high blowing ratios. It is also shown that the movement of the coolant is determined by the initial velocity direction, as well as the film cooling configuration.