A new method to measure hydrodynamic parameters of liquid–gas slug flow using ultrasound technique

The slug flow is a multiphase flow pattern widely found in many industries, like power generation, petrochemical, and oil and gas. Several experimental investigations have been done to estimate slug flow characteristics. Nevertheless, there is a lack of attention to assessing the gas velocity in the liquid slug and the evaluation of the applicability of the developed ultrasound techniques in media with different viscosity. In this context, this paper aims to show a new method, based only on ultrasound measurements, to estimate gas velocity in a liquid slug, Taylor bubble passage frequency, Taylor bubble length, and liquid slug length, as well as to analyze the effects of viscosity on slug flow characteristics assessed using ultrasound techniques. The experiments are carried out in a 2” vertical pipe with water–air or oil–air flows. The ultrasonic measurements were carried out using two piezoelectric transducers of 2.25 MHz central frequency in a pulse-echo mode. The raw echo signals acquired were processed to obtain the echo energy and time-of-flight signals to estimate the slug flow characteristics. The results indicate that the ultrasound method developed can estimate the slug flow characteristics in the water–air and oil–air two-phase flows.