Experimental investigation of mixing efficiency in particle-laden Taylor–Couette flows

This paper reports on original experimental data of mixing in two-phase Taylor–Couette flows. Neutrally buoyant particles with increasing volume concentration enhance significantly mixing of a passive tracer injected within the gap between two concentric cylinders. Mixing efficiency is measured by planar laser-induced fluorescence coupled to particle image velocimetry to detect the Taylor vortices. To achieve reliable experimental data, index matching of both phases is used together with a second PLIF channel. From this second PLIF measurements, dynamic masks of the particle positions in the laser sheet are determined and used to calculate accurately the segregation index of the tracer concentration. Experimental techniques have been thoroughly validated through calibration and robustness tests. Three particle sizes were considered, in two different flow regimes to emphasize their specific roles on the mixing dynamics.