Influence of electrostatic charges on the particle concentration in wall-bounded turbulent flows

Preferential concentration of inertial particles in wall-bounded turbulent flows is of paramount importance and, thus, subject of fundamental research. In practical applications of confined particle- laden flows the particles experience frequent collisions with the piping system which may result in an unwanted electric charge separation through triboelcctric effects. The consequential occurrence of electrostatic forces alters the particle trajectories and, thus, impairs the general validity of the measured results to an unknown extent. In this work the influence of triboelectric charging on the preferential concentration of inertial particles in a fully developed turbulent duct flow was investigated by means of a combined numerical and experimental approach. The order of magnitude of the potential charge accumulation was estimated and imposed in a parametric study to the particulate phase in the simulations. The simulations demonstrate that the concentration profiles are for the most part independent of the prescribed charge. However, the peaks of the particle number density at the walls caused by turbophoresis are strongly reduced through the local increase of repelling electrostatic forces. The comparison of numerical with experimental data indicates that the particles in the experimental setup are affected by a surface charge density of the order of 40 |iC/m2. The presented results aim to elucidate the impact of electrostatic forces in the particle distribution in wall-bounded particle-laden flows. .