Image Processing of a Plane Mixing Layer

Abstract

Vortical structure and mixing process of a confined plane mixing layer (u ₂/u ₁=0.67, angles of the confined walls = -4 - +6 degree) were visualized using a laser sheet and a high-speed imaging system at a rate of 333frames/s. The system detected an area of 40mm×50mm with a spatial resolution of 0.5mm. Images of water vaporconcentration in a high-speed side flow showed a two-dimensional coherent structure and its entrainment process. The visualized concentration images were analyzed to get average concentration, fluctuation intensity, and the spatial correlation. As the angles of the confined walls became larger, the mixing layer developed faster and the distance between the vortices decreased. Thefreq uency of the vortices was, however, 53Hz for all angles of walls.