Time-Resolved Three-Dimensional Concentration Measurements in a Gas Jet

Abstract

Turbulence can greatly influence reaction and heat transfer rates in fluids. The topology of the three-dimensional interface between mixing fluids directly determines the location and degree of reaction. The time-resolved measurement of the three-dimensional concentration field in a transitional gas jet is reported. A thin sheet of laser light was swept through the flow volume by a rotating mirror in a time brief enough that motion of the gas was minimal. The light sheet illuminated different parallel planes within the flow, and light scattered from particles seeding the jet was imaged onto a detector. The series of two-dimensional measurements made during one scan of the flow volume constituted a full three-dimensional mapping of structures within the flow. Computer graphics software was used to reconstruct and visualize three-dimensional surfaces of constant concentration and the magnitude of the concentration gradient vector over such surfaces.