Trailing vortices around a 45° pitched‐blade impeller

Abstract

The trailing vortex system near impeller blades has been identified as the major flow mechanism responsible for mixing and dispersion in stirred vessels

Flow Instabilities in Mechanically Agitated Stirred Vessels

“…Similar investigations on such transition may be found in the works of Hockey (1990) and Hockey & Nouri (1996). Schäfer et al (1998) observed by means of flow visualisation the flow discharged by a 45° PBT to be directed axially at higher Re and radially at lower Re. The flow stream direction was unstable, varying from radial to axial, for Re = 490-510.…”

Assessment of Large Eddy Simulations for Agitated Flows

“…In the entire vertical plane, midway between two baf es, velocities have been measured in a nely spaced grid by Schäfer et al 9 , see Figure 3(a). The average upward ow close to the tank wall only extends over a limited axial distance.…”

“…In the experimental work 9 , the Reynolds number (de ned as Re ND 2 =n, with N the angular velocity of the impeller (in rev s 1 ), D the diameter of the impeller, and n the kinematic viscosity of the uid) was set to 7,300. A cubic computational domain, consisting of 120 3 , 240 3 , or 360 3 grid nodes was de ned.…”

“…In this paper, results on the ow case de ned experimentally by Schäfer et al 9 will be presented. The case was chosen here because of the good quality of the experimental data available.…”

Entwicklung eines numerischen Berechnungsverfahrens für Rührwerksschwingungen

“…Für die Vermessung turbulenter Rührwerksströmungen eignet sich insbesondere die Laser-Doppler-Anemometrie, da sie zum einen in stark instationären und hochturbulenten Strömungsgebieten verlässliche Informationen liefert und zum anderen berührungslos arbeitet, so dass die Strömung nicht beeinflusst wird [28], [87], [88]. Bei dieser Methode wird durch zwei sich kreuzende, kohärente Laserstrahlen ein Interferenzmuster, bestehend aus hell-dunkel-Streifen, erzeugt.…”