Ultrasonic Attenuation of Gas-Solid Flow Pneumatic Conveying Fly Ash

Abstract

In order to set solid particle phase distributed uniformly in the whole detection space， the McClements model and Bouguer -Lambert -Beer law model were applied to formulate the ultrasonic attenuation properties of gas-solid flow for pneumatic conveying fly ash. The theoretical relation between the ultrasonic attenuation coefficients and the flow parameters of gas/ solids two-phase flow was established. By numerical simulations, the alteration laws of the ultrasonic attenuation coefficients with particle volume fraction， ultrasonic frequency and particle size were analyzed. The results show that the higher the ultrasonic frequency was, the greater the attenuation coefficients were. The ultrasonic attenuation coefficients linearly increased with the increasing of the solid particles volume fraction. If some fixed frequency was chosen， the slopes of attenuation -volume fractions curves can be confirmed by just testing ultrasonic attenuation coefficients under two volume fractions. So that testing of particle volume fraction corresponding to arbitrarily ultrasonic attenuation coefficients can be achieved. If the fly ash particle sizes were in the domain of 10 -200 μm with the same volume fraction， the ultrasonic attenuation coefficients monotonically decreased with the increasing of the particle size. But if the fly ash particle size was higher than 200 μm， the ultrasonic attenuation coefficients were no longer sensitive to the solids particle size.