title: 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.
authors.affiliation: Department of Electronic Engineering, Federal University of Technology-Paraná (UTFPR), Campus Toledo-PR, 85902-490, Brazil. fabiocoutinho@utfpr.edu.br.
authors.forename: Fábio Rizental
authors.initials: FR
authors.lastname: Coutinho
authors.affiliation: Graduate School on Electrical Engineering and Applied Computer Science, Federal University of Technology-Paraná (UTFPR), Campus Curitiba-PR, 80230-901, Brazil. ofuchi@utfpr.edu.br.
authors.forename: César Yutaka
authors.initials: CY
authors.lastname: Ofuchi
authors.affiliation: Graduate School on Electrical Engineering and Applied Computer Science, Federal University of Technology-Paraná (UTFPR), Campus Curitiba-PR, 80230-901, Brazil. lvrarruda@utfpr.edu.br.
authors.forename: Lúcia Valéria Ramos
authors.initials: LV
authors.lastname: de Arruda
authors.affiliation: Graduate School on Electrical Engineering and Applied Computer Science, Federal University of Technology-Paraná (UTFPR), Campus Curitiba-PR, 80230-901, Brazil. neves@utfpr.edu.br.
authors.forename: Flávio
authors.initials: F
authors.lastname: Neves
authors.affiliation: Graduate School on Electrical Engineering and Applied Computer Science, Federal University of Technology-Paraná (UTFPR), Campus Curitiba-PR, 80230-901, Brazil. rmorales@utfpr.edu.br.
authors.forename: Rigoberto E M
authors.initials: RE
authors.lastname: Morales