Numerical analysis of the effect of single and cascade air jets on heat and flow characteristics in plane surface heat sinks

Abstract

In this study, heat transfer performance with single and cascade air jets over the plane surface heat sink was numerically investigated with Ansys-Fluent software. Numerical analyses was carried out using the time-independent k-ε turbulence model. The effects of ten different Reynolds numbers (4000≤Re≤40000) and single and cascade nozzle numbers on the heat transfer were investigated. Analyzes were carried out at a distance of 40 mm between the nozzle and the heat sink. The air, on the other hand, was sent to the control volume at a temperature of 293.15 K at velocities corresponding to the determined Reynolds numbers. In the study, temperature contours showing the temperature distribution on the heat sink and streamline images in which turbulence formation is observed on the heat sink surface are presented. As a result, cooling performance increased with increasing Reynolds number in both nozzle types. It was determined that while the single nozzle showed a better cooling performance than the cascade nozzle up to approximately 38000 Reynolds number, better heat transfer was obtained with the cascade nozzle after 38000 Reynolds number. The Nusselt number showed an increase of 60% at the lowest Reynolds number in the single nozzle compared to the cascade nozzle, and 15% in the cascade nozzle at the highest Reynolds number compared to the single nozzle. It has been observed that the numerical results obtained are compatible with the experimental studies conducted with single and cascade air jets separately in the literature.