Simultaneous planar measurements of gas and particle velocities in particle-laden flows: proof-of-concept

Abstract

A laser-based technique is reported, employing simultaneous laser-induced fluorescence (LIF) and phosphorescence (LIP) to respectively mark the gas- and particle- phases and allow their simultaneous velocity measurement in a particle-laden flow. The technique discriminates the phases by optically separating the fluorescent and phosphorescent signals from each other and also from the scattering signals, thorough the novel use of optical filters and temporal separation. A proof-of-concept demonstration was conducted with using 250 μm PMMA spherical particles and 4 μm BAM:Eu²⁺ phosphorescent tracers, suspended in a water cuvette. Under 355 nm excitation (3rd harmonic of the Nd:YAG laser), both PMMA fluorescent and BAM:Eu²⁺ phosphorescent signals are shown to be sufficiently strong for imaging with CCD cameras, and sufficiently separable with using spectral filters and temporal profiles.