A new method of measuring two-phase mass flow rates in a venturi

The metering of the individual flow rates of gas and liquid in a multicomponent flow is of great importance for the oil industry. A convenient, non-intrusive way of measuring these is the registration and analyzing of pressure drops over parts of a venturi. Because of its importance, quite some attempts were made in the literature, but usually it is mandatory to additionally measure the void fraction. The main goal of the present work is the designing of a reliable measuring method for mass flow rates that only utilizes presssure drop recordings in a venturi. The approach followed consists of measuring flow patterns, void fractions and various pressure drops, and by relating pressure drop fluctuations in parts of the venturi to flow patterns. This paper presents a method to deduce the individual mass flow rates of air and water from pressure drop ratios and fluctuations in pressure drops. Void fractions are calculated from established correlations for the slip. Prediction results for a vertical venturi are compared with measurements, with void fractions up to 80 %, residual errors are quantified and the effect of the choise of slip correlation studied