Effect of slot-shaped pins on heat transfer performance in the extended jet impingement cooling

Abstract

In this study, effects of heat transfer performance on the roughened target surface with slot-shaped pins (SSP) were numerically investigated using an in-line array of extended jet impingement cooling models. The influence of pin heights on convective heat transfer for variable nozzle lengths, different pin arrangements, and Reynolds numbers (Re) in a rectangular channel flow was examined. The pins were located in a staggered and circular pattern. The numerical solution procedure has been verified by comparing numerical results with the available experimental data in the literature. The simulations were conducted with shear stress transport k-ω with low-Re correction turbulence model considering boundary conditions. The numerical model reasonably predicted heat transfer and pressure drop for flat plates and roughened plates with pins. Average Nusselt numbers on the surface were determined numerically using the model validated with experimental data for different dimensionless pin heights Hp/Dj (0.167, 0.417, and 0.667), various pin arrangements (R1, R2, R3), dimensionless nozzle lengths Gj/Dj (1.0, 2.0, and 6.0), and Re numbers (16250, 27100, and 32500). Numerical results were compared with the orifice plate; in other words, the conventional jet impinging configuration (Gj/Dj= 6.0 and Hp/Dj= 0). When the system's flow characteristics and performance evaluation criterion were considered, optimum geometric parameters for all Re were determined as Hp/Dj= 0.167 and R1_Gj/Dj= 1.0. Obviously, pin-roughened surfaces strongly affect the mean convective heat transfer and the homogeneity of the local heat transfer in extended jet impinging cooling systems. In this way, the negative effect of thermal stresses on the interested surface can be reduced, and the life of the material can be extended. Since the development of additive manufacturing technologies makes it possible to use these geometries in the internal cooling channels of gas turbine blades, a significant contribution will be made to the literature as a result of this study.