Comparative evaluation of oscillatory behavior and cooling performance of twin and single self-excited jets in a confined heated enclosure

Abstract

This study presents numerical simulations to investigate the oscillatory behavior and cooling performance of twin self-excited impinging jets in a heated enclosure. Simulations were carried out by a computational code developed on the OpenFOAM platform, and the shear stress transport (SST) model was used to consider turbulence characteristics. Flow field characteristics are evaluated at different nozzle spacing-to-width ratios S/e of 0, 3, 6, and 9 and inlet flow rates (Q) of 0.04, 0.06, and 0.08 m3/s. The effects of S/e and Q on the flow pattern, oscillation frequency, and the average Nusselt number Nuave on the enclosure’s impingement wall were examined. Results showed that, for S/e≤6, the two jets merge and oscillate as an equivalent single jet, while for S/e>6, two jets oscillate with the same frequency but are unsynchronized. The results also indicated that at Q=0.04m3/s, the use of a twin jet with S/e=0 can increase the Nuave by 12% compared to a single jet. By increasing the flow rate, the cooling performance of these two jets becomes more similar. The study found that increasing the nozzle spacing at a constant flow rate does not significantly affect the oscillation frequency, but it can reduce Nuave by about 50%.