Experimental Investigation of Ba e E ect on the Flow in a Rectangular Primary Sedimentation Tank

Abstract

In primary sedimentation tanks, short-circuiting enlargement of dead zones and high

ow mixing problems are caused by circulation regions (dead zones), which can reduce the optimal sedimentation of particles. For proper design of such tanks, the formation of recirculation zones should be avoided. The provision of a ba e as a geometrical modi cation of a tank may in uence the ow eld for better sedimentation. Thus, in this study, velocity measurements were performed by a three-dimensional Acoustic Doppler Velocimeter (ADV) to investigate ba e e ects on the velocity distribution in a primary rectangular sedimentation tank, quantitatively. E ects of ba e positioning were also determined. Mean

ow analysis shows how a ba e can alter the hydrodynamics of the ow eld. It was quantitatively found that the intermediate ba e not only in uences the ow eld in its downstream, but also a ects the ow pattern in its upstream. It was found that the ba e setting and its position relative to the inlet and outlet in uences the ow eld and the development of ow. Ba ed ow may provide better conditions for sedimentation by in uencing velocity pro les. However, further detailed experimental study is necessary to fully capture the ba e e ect and obtain further insight into the complex ow eld in a sedimentation tank.