Impingement/effusion cooling with a hollow cylinder structure for additive manufacturing

The aim of this study is to investigate heat transfer characteristics in new laminated plates having impingement/effusion cooling with a hollow cylinder structure. Three perforated plates are set up in parallel position to model impingement/effusion cooling system with a hollow cylinder structure. Local heat/mass transfer coefficients on all surfaces including upper surface of bottom plate, lower surface of mid plate, upper surface of mid plate, and lower surface of top plate in a new structure are obtained using the naphthalene sublimation method. The ratio of channel height to hole diameter, h/D, and the ratio of hole pitch to hole diameter, P/D, are fixed at 0.5 and 6, respectively. The range of the Reynolds number based on the hole diameter is from 2,000 to 7,000. For all tested surfaces, local Sherwood number shows high values near the stagnation region and at the regions where flow acceleration to the effusion hole occurs. A similar trend of the area-averaged Sherwood numbers on all tested surfaces except upper surface of bottom plate appears because of the flow regime variations depending on the Reynolds numbers. The new structure has higher value than existing other multi-layered structures, with an improvement of 32.4% in heat/mass transfer and 24.4% in thermal performance factor at Re-D = 5,000. A correlation between the area-averaged Sherwood number and the Reynolds number is obtained. This proposed structure will improve the thermal durability and reliability of the hot components of gas turbines by being implemented on hot components of gas turbines using an additive manufacturing. (C) 2020 Elsevier Ltd. All rights reserved.