We have conducted studies on the passive control of fluctuating velocity or the large vortex structure of jet flows in order to improve the
mixing and diffusion properties using a non-circular nozzle, a coaxial
annular nozzle, and vortex generator or tab which is fitted near the nozzle exit. The use of a resonance nozzle may be also an effective means of controlling jet flows. However, the details of the flowcharacteristics of the resonance jet have not been made clear.In this study, we experimentally clarify the flow characteristics of the round turbulent resonance free jet, such as resonance frequency, mean and fluctuating velocity profiles, jet spread, and others, and test its control by
changing the volume of the resonance room. As a result, we established that the fluctuation, the decay of centerline velocity, and also the resonance jet’s spread are much larger than those for a conventional jet. We also discuss the impinging jet resonance and the enhancing the heat transfer of the impinging jet using a resonance nozzle.