Visualization of Free Shear Flows by Planar Laser Scattering Method

Temporal vapor concentrations in a cylindrical jet were visualized by planar laser light scattering and a two-dimensional detection system. The light scattering signal was amplified about 10% by adding fluorescent dye in the vapor, and the vapor concentration was almost conserved in the visualized region of z/d=5-10. Two-dimensional distribution of the average concentration showed a trapezoid profile near the nozzle and a Gaussian profile in the developed region. The fluctuation intensity distribution showed peaks near the mixing region. Temporal behavior of the cncentration distributions indicated that three-dimensional large eddies existed in the jet, and that the entrainment of the ambient gas occurred by the eddies.