Author(s): Nikolai Stache; Tobias Bleninger; Bernd Hofmann; Gerhard Jirka; Matthias Maier; Karl Roth
Linked Author(s): Tobias Bleninger
Keywords: No Keywords
Abstract: Mixing efficiency and the related residence times need to be optimized in drinking water storage tanks to avoid microbiological pollution, especially in relation to flow variations. Field studies have been conducted in a drinking water storage tank in Karlsruhe Germany. The tank is operated either in filling-mode or emptying-mode, thus unsteady flow conditions and changing water levels. Flow velocities and current structures have been observed by using three ADV probes and small drifters recorded by a video camera. The results are compared to a laboratory model (scale 1:10) using flow visualisations with coloured dye. The correct scaling of the laboratory set-up is defined by the discharge pipe Reynolds-number on one hand, and a tank Reynolds-number on the other hand, without exceedance regarding the Froude effects. Due to the existing flow conditions within the tank from highly turbulent near the discharge pipe, down to laminar flow in the corners a different scaling approach for tank and pipe size for further quantitative lab studies has been proposed.
Year: 2009