Computational study on self-oscillatory flow induced by vertical and horizontal jets in partially heated and cooled cavities

Abstract

In recent years, non-isothermal jets have received much attention due to their wide range of applications in the industry. The present work concentrates on comparing the buoyancy mediating effects on the performance and oscillating behavior of horizontal and vertical self-excited jets. To this aim, the oscillating behavior and performance characteristics of self-excited jets in horizontal and vertical directions have been simulated and compared under different thermal boundary conditions (e.g., heated, cooled, and adiabatic wall cavities). Computational solutions were obtained using unsteady Reynolds averaged Navier-Stokes (URANS) and energy equations for an incompressible flow. Investigations have been performed for different nozzle thicknesses/widths (0.5–2 cm) at a constant flow rate and inlet temperature of 300 K. The results showed that non-isothermal conditions did not significantly affect the oscillating behavior of horizontal jets, while this could be much more dramatic in vertical jets. In vertical jets with a nozzle thickness of 2 cm, under non-isothermal conditions, the oscillation frequency and the average Nusselt number are about 17% and 40% different from those of the isothermal jet, respectively. The results also indicated that when the Archimedes number exceeds 0.1, the effect of the jet orientation on its performance and oscillating behavior will be more pronounced.