MEASUREMENT OF THE LOCAL INTENSITIES OF SEGREGATION WITH THE TOMOGRAPHIC DUAL-WAVELENGTH PHOTOMETRY

The newly developed tomographical dual wavelength photometry enables t he measurement of the local intensity of segregation at a multitude of points inside the stirred vessel. This is done by injecting a mixture of an inert and a reacting dye into the vessel. The inert dye serves as a tracer for the macromixing, whereas the vanishing of the reacting dye shows the micromixing. The concentration fields of the dyes are m easured simultaneously by transluminating the vessel from three direct ions with superimposed laser beams of different wavelength. The light absorption by the dyes is measured with CCD-cameras and these projecti ons are used for the tomographic reconstruction of the concentration f ields. Low Reynolds number measurements with a Rushton turbine show be tter macro- and micromixing, for a dye injection closer to the stirrer shaft compared to a position closer to the main vortex.