Generalized Correlations for Inertial Impaction of Particles on a Circular Cylinder

Abstract

The trajectories of spherical particles impacting a relatively larger circular cylinder in crossflow are calculated using finite difference methods to solve the equations of motion in a Lagrangian form. Drag forces on the particles are described using an empirical correlation for the drag coefficient (as a function of Reynolds number) and the solution for steady, inviscid, incompressible flow (potential flow) around a circular cylinder. Numerical integration of the particle equations of motion is started upstream of the cylindrical target, and calculations are carried out until the particle impacts the cylinder or bypasses it completely. The effects of particle interception are neglected. Results for target efficiency and angle of impingement compare favorably with previous numerical solutions at low-particle Reynolds numbers but are found to be more accurate for free-stream velocity Reynolds numbers (Re₀) > 1. In addition, results for particle velocity, angle of impact, and particle concentration are presented. Generalized correlations are developed to describe target efficiency, local impingement efficiency, impact velocity, and impact angle of particles on the cylinder surface. Correlations are valid for Stokes numbers (Stk) ≥ 0.125 and Re² ₀/Stk ≤ 50,000. These results serve as useful tools in performing engineering calculations without requiring lengthy computations of particle trajectories.