Direct Numerical Simulations of Free Jets Emerging from A Precessing Nozzle

Abstract

Control of turbulent jets is an essential research topic in fluid mechanics with many industrial applications, such as cooling electric devices, combustion engines, chemical mixing, and air conditioning. Recently, attention has been paid to the blooming jet, and detailed control parameters have been clarified. In this study, we propose a mechanical precessing nozzle with axisymmetric excitation to realize the blooming jet from the viewpoint of feasibility. We conduct the DNS of the proposed method for typical control frequency ratios found in the previous literature of the blooming jet. It is clarified that blooming and bifurcating mode can be reproduced by the proposed method and that high mixing performance is confirmed by evaluating the mixing characteristics. Furthermore, the dominant modes in the flow are clarified by the analysis with the DMD method.