Internal and external cooling of a full coverage effusion cooling plate: Effects of double wall configuration and conditions

摘要

AbstractThe present study provides new heat transfer data for both the surfaces of the full coverage effusion cooling plate within a double wall cooling test facility. To produce the cooling stream, a cold-side cross-flow supply for the effusion hole array is employed. Also utilized is a unique mainstream mesh heater, which provides transient thermal boundary conditions, after mainstream flow conditions are established. For the effusion cooled surface, presented are spatially-resolved distributions of surface adiabatic film cooling effectiveness, and surface heat transfer coefficients (measured using infrared thermography). For the coolant side, presented are spatially-resolved distributions of surface Nusselt numbers (measured using liquid crystal thermography). Of interest are the effects of streamwise development, blowing ratio, and Reynolds number. Streamwise hole spacing and spanwise hole spacing (normalized by effusion hole diameter) on the effusion plate are 15 and 4, respectively. Effusion hole diameter is 6.35?mm, effusion hole angle is 25°, and effusion plate thickness is 3 hole diameters. Considered are overall effusion blowing ratios from 2.9 to 7.5, with subsonic, incompressible flow, and constant freestream velocity with streamwise development, for two different mainstream Reynolds numbers. For the hot side (mainstream) of the effusion film cooling test plate, results for two mainflow Reynolds numbers of about 145000 and 96000 show that the adiabatic cooling effectiveness is generally higher for the lower Reynolds number for a particular streamwise location and blowing ratio. The heat transfer coefficient is generally higher for the low Reynolds number flow. This is due to altered supply passage flow behavior, which causes a reduction in coolant lift-off of the film from the surface as coolant momentum, relative to mainstream momentum, decreases. For the coolant side of the effusion test plate, Nusselt numbers generally increase with blowing ratio, when compared at a particular streamwise location and mainflow Reynolds number.Highlights?Data are given which illustrate the performance of a sparse effusion hole array which is supplied by a cross flow arrangement.?Presented are new experimental data for both the hot/mainstream side, and the cold/cross flow side of the effusion plate.?Considered are streamwise development, blowing ratio, cross flow Reynolds number, and mainstream flow Reynolds number.?For the hot side (mainstream) of the effusion film cooling test plate, adiabatic cooling effectiveness values and heat transfer coefficients are higher as Reynolds number decreases.?For the coolant side of the effusion test plate, Nusselt numbers generally increase with blowing ratio, as well near the entrances of effusion holes.