Measured dependence of the attenuation of audio-frequency sound on concentration in flowing particulate suspensions

摘要

The relationship between the attenuation of sound at frequencies between 500 and 3500 Hz and the concentration of flowing suspensions of various powdered solids has been explored. The suspensions were conveyed in a pipeline of 53 mm diameter andthe particle concentration was varied up to a maximum of 2.8 kg/kg. Three materials were tested: flour (mean radius. 27μm). olivine sand (mean radius, 278μm) and barytes. The feasibility of measuring the acoustic attenuation of particulate suspensionsat audio-frequencies and relating the measured attenuation to concentration has been demonstrated. Although the audio-frequency attenuation is smaller at a given concentration than at ultrasonic frequencies, audio-frequency measurements are lesssusceptible to inhomogeneity of flow and to in-pipe turbulence than ultrasonic measurements.