| 论文简介 |
Particle agglomeration in turbulent flows plays an important role in the formation process of atmospheric pollution and the control technology of fine particulate matter. In this work, an experimental platform was built to study the structure characteristics, including geometric size, row number, spanwise pitch, longitudinal pitch and arrangement, of the vortex generators affecting the particle agglomeration. At the flow velocity of 4.8 m/s, the optimal agglomeration efficiency within the particle size range of 15.7–850.0 nm is about 16.42%. The three agglomeration morphologies of multi-branched particle tree, long strip-shaped particle chain and stacked particle ball are observed and characterized through the three parameters of void content, degree of sphericity and dynamic shape factor. Moreover, a numerical model, considering the Brownian collision of the slip flow regime and the aerodynamic collision of the inertialess particles, was developed to analyze the distribution and collision of the particles in the vortexes. The simulation results indicate that the windward boundary layers of the vortex generators and the longitudinal edges of the vortexes are main areas where collision and agglomeration occur. Under the staggered arrangement, the windward boundary layers are beneficial to facilitate the transverse motion of particles, but also form the transverse local enrichment. Finally, a dimensionless criteria Ag (Agglomeration number, abbreviated as Ag) was put forward to evaluate the agglomeration ability of the vortex generator. |
(创新港)
