Gas‐filled cavity structures and local void fraction distribution in aerated stirred vessel

The local structural function obtained by a microresistivity probe at different hydrodynamic regimes is examined. The structures, such as the vortex‐clinging structure, the appearance of one and two large cavities, small 3‐3 structure, large 3‐3 structure, and ragged cavities were recognized by frequency transformation of the time‐domain structural function. An optimized phase discrimination in signal processing was used. The distribution of the local void fraction (α) in a pilot‐size stirred tank was experimentally investigated, because almost no such data can be found in the literature. The two‐phase mixture was composed of air and water; α was measured at 190 nodes in the vertical half‐section plane of the vessel. Relative differences smaller than 9% between integrated values of α and measured gas holdups agreed reasonably well under all conditions.