Laser-Doppler measurements of the turbulent flow in stirred vessels to establish scaling rules

✍ Scribed by K. Van Der Molen; H.R.E. Van Maanen

• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 792 KB
• Volume: 33
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(78)85081-7

✦ Synopsis

A laser-Doppler velocuneter. equipped with a frequency shift so as to elunmate duecuonal ambwlty, has been used to measure the turbulent flow m stvred vessels with duuneters of 0 12.0 29 and 0 90 m of the same geometry The vessels contamed water and measurements were done in the unpeller stream relpon Scahng rules have been derived for average velocity, the permdlc component. turbulent mtenslws and turbulence power spectra It appears that close to the unpeller the Bow IS dommated by the penod~cally fiuctuatmg flow of the tradmg vortxes behmd the unpeller blades The normahzed mean velocity m the tradmg vortices. and therefore the turbulence mtenslty close to the Impeller. IS very sensltrve to unpeller geometry and shows a sbght mcrease with size of the vessel In the greater part of the unpeller stream regmn the power spectra have a sectmn wth a -512 slope on a log-log scale and consequently the energy of the small eddles decreases with masing scale At the vessel wall the vortrccs have decayed completely to random turbulence and the spectrum shows a -5/3 slope