Active flow control by countercurrent jets

The paper presents the results of experimental analysis of the flowfield in slightly heated countercurrent round jets. The velocity measurements were carried out by means of hot-wire anemometry (a combined CTA-CCA system for temperature compensation). The instantaneous signals collected during the experiment were digitally processed and used for determination of the statistics of velocity and temperature fields including frequency characteristics. The results revealed that the fluid aspiration at the jet periphery significantly influences large-scale structures naturally existing in the flow and being responsible to a great extent for the mixing and entrainment in the free flow. The aspiration intensity was found as the key parameter deciding about the way the reverse flow either inhibits or enhance transport processes.