SUBSTRATE CHARACTERISTICS OF MULTIPLE ARRAYS OF TURBULENT SWIRLING IMPINGING JETS

Abstract

This research investigates the flow aspects and thermal behavior of multiple air jet impingements on a flat plate through two different geometrical arrangements. A variety of flow conditions and geometrical parameters are considered including Reynolds number, swirl number, impingement distance, and jet-to-jet separation. A numerical approach is adopted to conduct the analysis using the shear stress transport (SST) k-ω turbulence model in the commercial computational fluid dynamics (CFD) software package ANSYS Fluent v17. Results reveal that the static pressure is uniformly distributed on the impingement surface for the higher nozzle-to-surface distance at a strong swirl flow, while for noswirl and medium-swirl configurations, the static pressure is accumulated at the stagnation regions. A lower impingement distance improves the cooling performance while a higher impingement distance accelerates the consistency in temperature distribution. Moreover, the staggered nozzle arrangement is found superior in terms of generating integrity in thermal cooling. Overall, the pressure coefficient enhances by up to 126% for medium swirl (S = 0.3) and 67% for high swirl (S = 0.75) cases, and in terms of Reynolds number (Re), the pressure coefficient decreases by 12% and 15% for Re = 24,600 and 35,000, respectively, compared to Re = 11,600. Besides, the average Nusselt number amplifies by 8% and 17% for medium (S = 0.3) and high swirl (S = 0.75) flow, respectively, while compared to Re = 11,600, the average Nusselt number raises by 58% and 98% for Re = 24,600 and 35,000, respectively. The eddy viscosity increases strongly with the growth of swirl intensity, while a monotonous vorticity distribution is achieved at high swirl conditions.