Numerical investigation of electrostatic effect on particle behavior in a 90 degrees bend

Abstract

Particle behavior in a turbulent circular-sectioned 90° bend under electrostatic field at three air flow rates (1600 L/min, 1100 L/min and 950 L/min, the corresponding bulk Reynolds numbers are 58,000, 40,000, 34,000) is simulated by a Large Eddy Simulation-Lagrangian particle tracking technique (LES-LPT) method coupled with electrostatic field model by Coulomb’s law. This numerical simulation is dedicated to study the electrostatic effect on particle behavior and erosion occurred in the dilute particle-laden bend flow. Forces considered acting on particles includes drag, lift, gravity and electrostatic force. Results obtained for the fluid phase are in good agreement with experimental and numerical data. Predictions show that electrostatic field does affect the particle motion in the pipe bend. At higher air flow rate with higher electrostatics at the inner arc the increasement of impact angle is lower than that at lower flow rate with lower electrostatics. The same conclusion can be found at the outer arc. In addition, electrostatic effect does increase particle-wall impact velocity while such trend decreases with flow rate. Erosion rate increases with increasing air flow rate, which is independent of electrostatics. However, given the same flow rate, the electrostatics reduces the occurrence of erosion at the bend. The erosion rate under electrostatic effect is found to approach that without electrostatics as the flow rate increases. Therefore, the effect of electrostatics on erosion decreases with the air flow rate.