抄録
When a low density gas compared with the ambient gas is discharged from a round nozzle, side jets that are radial ejections of jet fluid are generated at the initial region. The density ratio between the jet fluid and the ambient fluid is a main parameter for side-jet formation. Since the side-jet formation is also related to the instability of shear layer, another parameter is a ratio of the momentum thickness and the nozzle diameter at the nozzle exit. Compressibility suppresses the generation of the side jets. The variable-density jets were issued from two round nozzles, which have different area contraction ratio, with various jet-speed. Effects of the density ratio, the momentum thickness ratio and the Mach number, which is defined by the issuing conditions, on the side-jet formation are researched experimentally. An existence of side jets was confirmed by flow visualization using a laser sheet.
