Investigating the unsteady dynamics of a multi-jet impingement cooling flow using large eddy simulation

Abstract

We investigate the unsteady behavior of an in-line jet impingement array of nine jets at a Reynolds number of $10\,000$ in a narrow channel subjected to a developing cross flow of up to 25\% of the bulk jet velocity. To this end, we present an improved version of a previously published large eddy simulation (LES) now with resolved turbulence at the inflow boundaries. After a careful analysis of the transient behavior and statistical convergence of the LES, we discuss the time-averaged heat transfer characteristics of the configuration compared to numerical references of similar configurations. We then show how the large-scale unsteadiness increases from jet to jet. Both space-only and spectral proper orthogonal decompositions (POD and SPOD) are used to discuss the large-scale organization of single jets and multiple jets in combination. The latter shows a qualitative change in the unsteady behavior of the temperature footprint on the impingement wall with increasing cross flow.