Axis-switching Phenomena and Flow Characteristics for Non-circular Jets with Density Differences

Axis-switching phenomena and mixing characteristics were numerically investigated for noncircular jets with different densities. Four fluids of hydrogen, methane, air, and propane were adopted for circular, square, and triangular jets injected into ambient air. The Reynolds number based on the equivalent diameter was fixed at 10,000. From the results of the axial velocity decay and jet half width, effects of the density differences on the flow mixing of noncircular jets were discussed. The source terms in the vorticity transport equation were analyzed for the flow structure of axis-switching phenomenon. Depending on the density of jet fluid, axis-switching phenomenon was affected very differently. In light jets, the density difference hindered the axis-switching phenomenon, but the opposite effects of the density difference were obtained for heavy jets.