Self-oscillating jets in cooling applications

Abstract

In the present computational study, an assessment of self-oscillating jets for use in cooling applications is investigated. The jet exits from a square nozzle into a narrow rectangular cavity at a Reynolds number of 54,000 based on nozzle hydraulic diameter and average jet exit velocity. The heated devices, such as electronic chips, are located externally on the surface of the cavity. A three-dimensional numerical simulation of the flow is conducted by solving the unsteady Reynolds-Averaged Navier-Stokes and energy equations to assess the thermal features of the flow field. The unsteady Elliptic Blending Reynolds Stress Model, which consists of transport equations for each of the stress tensor components, was used to model turbulence. The cooling performance of a self-oscillating jet is compared with that of a wall jet and a channel flow for the same flow conditions and the same arrangement of the hot devices. The cooling efficacy of two different arrangements of the heated devices is also evaluated. The self-oscillating jet provides a higher heat transfer for the heated blocks which are located farther from the central region, while the wall jet improves heat transfer around the central region. Self-oscillating jets can improve heat transfer over a larger area when the heated devices are aligned orthogonal to the axis of the nozzle. On a Nusselt number comparative basis, the channel flow provides the least desirable heat transfer performance.