On the aero-thermal performance of flat-plate film cooling hole with variable rib heights

Abstract

This study conducted a numerical investigation into the impact of different cooling air feeding methods and structural parameters of the internal ribbed crossflow channel on the performance of cylindrical film cooling holes under varying blowing ratios. The considered flow conditions encompassed two feeding methods (plenum or crossflow channel), three different rib heights (h = 2–8 mm), three internal crossflow directions relative to the mainstream (θ = 0°–180°), and four blowing ratios (M = 0.5–2.0). In the case of crossflow, the external crossflow had a Mach number of 0.3, and the internal crossflow's Reynolds number was set at 2 × 105. The study delves into flow analyses of the hole and external flow field, discharge coefficient characteristics, aerodynamic losses, and heat transfer characteristics. The findings reveal that the presence of internal crossflow significantly alters the flow field and performance compared to the coolant plenum case. However, the effects of crossflow are attenuated when internal turbulence rib structures are introduced, and this damping effect is further pronounced as the rib height increases. The aerodynamic and cooling characteristics of the hole progressively approach those of a plenum supply form, a phenomenon aptly termed the “Plenum effect” of the ribbed crossflow channel.