FLOW MEASUREMENTS AROUND A STATIC MIXER USING LASER-DOPPLER ANEMOMETRY, PARTICLE IMAGE VELOCIMETRY AND LASER-INDUCED FLUORESCENCE

摘要

Liquid phase hydrodynamics and mixing behavior around a static mixer have been investigated using Laser-Doppler Anemometry (LDA), Particle Image Velocimetry (PIV) and Laser-Induced Fluorescence (LIF). A SMX-type mixer geometry has been chosen as a first configuration. It consists of seven rectangular lamellas: four are orientated in the direction of the flow; between them, three are turned against the flow. For the experiments the round shapes of duct and mixer have been changed to a square shape in order to get a better optical access for the measurements. Water is used as flow medium. Laminar, transitional and turbulent conditions in the inflow section have been investigated. Three-dimensional velocity fields are measured in vertical sections in the inflow duct and vertically and horizontally in the perturbed outflow. Behind the mixer, the structure of the velocity field mimics the mixer geometry in all three directions. Due to a long acquisition time LDA gives point-wise velocity components in all three directions, which are only representative of the time-averaged velocity field but not of vortex-induced fast flow fluctuations. PIV data has been used to calculate stream lines for the mean flow with different inflow conditions. The velocity fields have been compared and analyzed. In the outflow sections, LIF measurements have been carried out along vertical sections. The injected tracer-dye is Rhodamine 6G. Mixing behavior (segregation index) and frequency characterization of the vortex structures induced by the mixer have been analyzed.