Polydisperse particle size characterization by ultrasonic attenuation spectroscopy for systems of diverse acoustic contrast in the large particle limit

Abstract

Ultrasonic attenuation spectroscopy offers advantages over other spectrometric methods for the determination of suspension and emulsion size distributions. One advantage is the possibility of conducting measurements in highly concentrated or optically opaque dispersions. Models useable for the inversion of measured attenuation spectra to calculate particle size distributions are available and widely used, but their applied forms only allow for the characterization of particles smaller than 10μm. In this paper, a methodology using the Faran model for elastic scatterers is examined in the region of micrometer-sized particles with respect to its suitability for the prediction of measured attenuation spectra and size distributions of various material combinations. All selected particle fractions and fluid materials were characterized independently from ultrasonic attenuation spectroscopy with respect to their material properties, size distributions, and shape. A comparison of measured and calculated attenuation spectra shows an acceptable agreement. The chosen methodology for particle sizing applications is further confirmed if a fit of the model to the measurement data is performed. In this approach, the solids volume fraction is treated as the only fit parameter. The findings indicate that the methodology is suitable for polydisperse particle size characterization for a wide range of acoustic contrast.