2-PHASE FLOWS BY PULSED-FIELD GRADIENT SPIN-ECHO NMR

Pulsed field gradient nuclear magnetic resonance was performed on air- water mixtures flowing through a circular pipe. Analysis of the spin e cho signals established the validity of the technique to measure the m ean velocity and the velocity probability distribution in laminar and turbulent flows of liquid water (one phase) in a long circular pipe. T he purpose of this study was to extend the method to the case of two-p hase air-water flows. A full procedure is proposed and demonstrated fo r deriving different basic characteristics of these flows: void fracti on, mean liquid velocity, liquid volumetric flux and mean velocity pro bability distribution. The experimental results, reported for various void fractions (0-0.5) and liquid volumetric fluxes (up to 25 cm s-1), extensively illustrate the capabilities of this method.