Characterization of the Velocity and Concentration of Pneumatically Conveyed Particles in the Upstream of an Acoustic Emission Waveguide Through CFD-DEM Modeling and Electrostatic Sensing

The characterization of the velocity and concentration of pneumatically conveyed particles in the upstream of the waveguide protruded into the flow is essential for the measurement of the mass flow rate and size distribution of particles using acoustic emission (AE) methods. However, the protrusion of the waveguide affects the movement of particles, and there is a challenge in quantifying its effects on particle velocity and concentration due to the complexity of the dynamics of particle flow. Therefore, the computational fluid dynamics-discrete element method (CFD-DEM) is employed in this study to simulate the collisions between particles and waveguides with a varying protrusion depth in both circular and square vertical pipes. The modeling data indicate that in circular and square pipes, the waveguide protruded into the flow between 2 and 10 mm results in a reduction in particle velocity of about 30.6%-32.7% and 30.8%-32.9%, respectively, and an increase in particle concentration of about 3.5%-15.6% and 4.0%-17.3%, respectively. Based on the modeling data, a sensing system incorporating electrostatic sensors is developed to measure the particle velocity and concentration in the upstream of the waveguide. Experimental tests were carried out on both circular and square vertical pipes on a particle flow test rig. Experimental results show that in circular and square pipes, the waveguide protruded into the flow between 2 and 10 mm results in a reduction in particle velocity of approximately 32.5%-34.5% and 32.7%-34.8%, respectively, and an increase in particle concentration of approximately 4.1%-19.5% and 4.6%-21.8%, respectively. The experimental results show a close agreement with the modeling data.