A New Method for Ultrasound Detection of Interfacial Position in Gas-Liquid Two-Phase Flow

Abstract

Ultrasonic measurement techniques for velocity estimation are currently widely used in fluid flow studies and applications. An accurate determination of interfacial position in gas-liquid two-phase flows is still an open problem. The quality of this information directly reflects on the accuracy of void fraction measurement, and it provides a means of discriminating velocity information of both phases. The algorithm known as Velocity Matched Spectrum (VM Spectrum) is a velocity estimator that stands out from other methods by returning a spectrum of velocities for each interrogated volume sample. Interface detection of free-rising bubbles in quiescent liquid presents some difficulties for interface detection due to abrupt changes in interface inclination. In this work a method based on velocity spectrum curve shape is used to generate a spatial-temporal mapping, which, after spatial filtering, yields an accurate contour of the air-water interface. It is shown that the proposed technique yields a RMS error between 1.71 and 3.39 and a probability of detection failure and false detection between 0.89% and 11.9% in determining the spatial-temporal gas-liquid interface position in the flow of free rising bubbles in stagnant liquid. This result is valid for both free path and with transducer emitting through a metallic plate or a Plexiglas pipe.

Design and characterization of immersion ultrasonic transducers for pulsed regime applications

“…Non-destructive testing, flow metering [1][2][3][4] , material evaluation [5] and medical diagnosis [6,7] are the major application areas. Furthermore, ultrasonic transducers are widely used for the measurement of diverse quantities, such as detection of interfacial position on two-phase (gas-liquid) flows [8] , short range vehicle detection in smart cars [9] , or measurement of thickness, position, or fluid properties such as density, viscosity, etc. The measurement principle used in the cited applications usually consist in observing changes in the velocity or the intensity of the ultrasonic wave, and to deduce the This is the post-print (i.e.…”

Two Models of Electrical Impedance for Electrodes With Tapwater and Their Capability to Record Gas Volume Fraction

“…3) is coincident with the slice sensed by the electrodes. There are some volume fraction experimental measurement techniques (Prasser, 2007;Falcone, 2009b;Coutinho et al 2014) such as the acoustic attenuation, microwave attenuation, ultrasound, tomography, wire-mesh and electrical impedance. This last technique is the simplest and probably the cheapest of all techniques (Rocha, 2008) and allows measurements of the void fraction with resolution times of 10 −3 s and smaller.…”