Experimental studies of turbulent Taylor-Couette flows: single phase and liquid-liquid dispersions

TL;DR

This paper investigates turbulent Taylor-Couette flows with liquid-liquid dispersions, analyzing flow characteristics, turbulence transition, and dissipation, revealing that two-phase flows can significantly increase torque compared to single-phase flows.

Contribution

It provides the first detailed experimental analysis of liquid-liquid dispersions in turbulent Taylor-Couette flows, including flow characterization and dissipation measurements.

Findings

Torque per unit mass can double in two-phase flows.

Flow transition thresholds are characterized.

Long-term flow behaviors are observed.

Abstract

We study liquid-liquid dispersions in a turbulent Taylor-Couette flow, produced between two counterrotating coaxial cylinders. In pure Water and in counterrotation, Reynolds numbers up to 1.4 10^5 are reached. The liquids we use are a low-viscous Oil and pure Water or a Sodium Iodide solution with a refractive index matched to that of Oil, in order to get transparent dispersions. We first characterize the single-phase flow, in terms of threshold for transition to turbulence, scaling of the torque and measurements of the mean flow and of the Reynolds stress by stereoscopic PIV. We then study the increase of the dissipation in the two-phase flows and find that the torque per unit mass can be twice the torque for a single-phase flow. Long-time behaviours are also reported.