A portable laser light-scattering probe for turbulent diffusion studies

Abstract

A new instrument has been devised, based on light scattering principles, to measure real‐time concentration variation in a turbulent flow. Used for turbulent diffusionmeasurements in a wind tunnel boundary layer, it can also be utilized for other turbulentmixing studies as well. The instantaneous concentration was detected by means of a 5 mW He–Ne gas laser as a light source, dioctyl phthalate aerosols as tracer particles, fiber optics as the scattered light transmitter, and a photomultiplier as a scattered light sensor. The instrument was designed to be moved to any location in a wind tunnel to measure steady or unsteady diffusion processes.