Enhancement of submicron particle deposition on a semi-circular surface in turbulent flow

Abstract

Air pollution due to suspended particles in the built environment threatens people’s health. The collection of submicron particles using air cleaners is especially difficult due to their tiny sizes. Surface patterned structures can enhance submicron particle deposition, thus improving the performance of an air cleaner. In this study, a semi-circular micro-structured surface was designed and optimized by considering particle deposition enhancement and reduction of pressure differential. The maximum efficiency ratio at the pitch-to-height ratio (α) of 3 reached 1137 for the 1 µm particles but only 3.4 for 0.01 µm particles. The main mechanism of enhancing submicron particle deposition depends on the capture of the recirculation wake induced by semi-circular structures and entrainments of large turbulence kinetic energy to the near-wall regions. Submicron particles was observed to deposit between cavities on the semi-circular surface at a small α. This study shows that surface patterned structures in the semi-circular shape at small α can enhance the submicron deposition efficiency, thus providing a possible approach to improve the overall efficiency of air cleaners.