Particle imaging velocimetry for sooting flames with scattering suppression

Abstract Light scattering from soot particles in hydrocarbon flames presents a significant source of background noise in particle image velocimetry (PIV) measurements. To mitigate this effect, the relative scattering intensities of 200 nm PIV seed particles and soot particles in a hydrocarbon-air flame were optimized for a 90 ∘ viewing angle. A polarization control assembly-comprising a Pockels cell, vertical polarizer, and half-wave plate-was implemented to vary the incident light polarization angle relative to the scattering plane. The observed trends in scattered irradiance agree with Lorenz–Mie theory predictions for the ratio of scattered light from a single PIV seed particle to that from a single soot particle, across a range of polarization angles. Experimental single-shot PIV images qualitatively illustrate the resulting improvements. Reduced soot-scattered light led to decreased velocity vector uncertainty and a lower incidence of vector dropouts in the processed PIV fields.