Taniguchi N.: PIV and LIF Measurements on the Lobed Jet Mixing Flows

Abstract: The effect of lobed nozzle on the vortical and turbulent structure chnages in the near field (X/D<3.0) of the jet mixing flow had been conducted experimentally in the present study. The techniques of planar Laser Induced Fluoresce (LIF) and Particle Image Velocimetry (PIV) were used to accomplish the flow visualization and velocity field measurements. The experimental results showed that, compared with a circular jet mixing flow, lobed jet mixing flows were found to have shorter laminar region, smaller scale of the spanwise Kelvin-Helmholtz vortices, earlier appearance of small scale turbulent structures and thicker mixing layers in the near field of the jet mixing flow. Bigger high-turbulence intensity regions were found to concentrate at the region of X/D<2.0 for the lobed jet mixing flows. All these indicted the better mixing enhancement performance of a lobed nozzle over a conventional circular nozzle at the near field of a jet mixing flow