Numerical Investigation on Oscillation Behavior of a Non-isothermal Self-excited Jet in a Cavity: The Effects of Reynolds Number and Temperature Differences

A self-excited oscillating jet can be naturally produced by discharging a plane jet into a rectangular cavity due to pressure effects and without a need for external aid. In recent years, the self-oscillatory jet in non-isothermal conditions has attracted research interests because of its wide range of industrial applications. Therefore, the current study aimed to compare the oscillatory behavior of downward vertical self-excited jet with Reynolds number (Re) ۱۰۰۰ and ۳۰۰۰ under various temperature differences (۰, ۱۰۰, and ۳۰۰ K) between inletflow and cavity’s wall. Computational solutions were obtained using unsteady Reynolds averaged Navier-Stokes (URANS) and energy equations for an incompressible flow. The numerical simulation was carried out by the finite-volume based tool OpenFOAM code. The results showed that depending on the value of temperature difference, oscillatory and non-oscillatory flows were observed. Also, at Re=۳۰۰۰, the temperature differences can change oscillation frequency up to ۱۰% compared to isothermal conditions. This value reaches ۵۸% at Re=۱۰۰۰. The results indicated that where the Archimedes number is less than ۰.۱, the effects of temperature differences between jet and cavity walls on the oscillating behavior are negligible.

Keywords:

Self-excited oscillating jet , Mixed convection heat transfer , Impingement flow