Modified discrete phase numerical model for calculating ultrasonic coagulation in Eckart flows

Abstract

One of the most effective methods for trapping aerosol particles is the preliminary combination of particles into agglomerates under the action of high-intensity sinusoidal ultrasonic (US) oscillations (ultrasonic agglomeration) for further trapping of coarse particles by traditional methods (inertial or gravitational settling, filtration through a porous material, etc.). To date, the effectiveness of ultrasonic agglomeration has been repeatedly proven for particles larger than 2.5 μm. However, ultrasonic agglomeration, based on the known mechanisms of particle interaction, is not very effective when exposed to particles smaller than 2.5 μm and especially less than 1 μm. At the same time, the possibilities of a linear acoustic field are well studied today and it has been established that exposure to a linear acoustic field does not provide effective coagulation of PM2.5 particles. And with an increase in the sound pressure level of a linear acoustic field, coagulated particles (especially when it comes to solid particles) begin to break down. Therefore, the authors proposed to use nonlinear effects, which consist in the formation of vortex acoustic (Eckart) flows that can cause a local increase in the concentration of particles and, consequently, an increase in the efficiency of coagulation. It has been established that the formation of vortex acoustic sweats in the resonant gap can additionally increase the efficiency of ultrasonic coagulation by at least 1.5 times.