Characterization of the Velocity Field in a Small, Cylindrical, Low Reynolds Number Aerosol Sampling Cyclone

Abstract

A laser Doppler velocimeter capable of simultaneously measuring two components of velocity was used to measure the flow field in a 88.9-mm diameter, cylindrical, reverse-flow, multiport cyclone. A third component was measured by reorienting the cyclone. The components measured were those in the radial, axial, and tangential directions with the tangential component being measured in both orientations. The ratio of velocities was Ũ _θ:Ũ _z:Ũ _R = 100:10:1. At a flow-rate Reynolds number, N _RQ= (4pQ)/(πμD _c), of approximately 860, values of turbulence intensity for each component within the cyclone were on the order of 10% when determined as the component standard deviation normalized to the mean flow. The vortex structure is dependent upon Reynolds number.