Signals features extraction in liquid-gas flow measurements using gamma densitometry. Part 1: time domain

¹ Rzeszow University of Technology, 35-959 Rzeszow, Poland
² AGH University of Science and Technology, 30-059 Krakow, Poland
³ Test & Measurement Solutions sp. z o.o., 53-025 Wrocław, Poland

^a Corresponding author: rohan@prz.edu.pl

Published online: 28 March 2016

Abstract

The paper presents an application of the gamma-absorption method to study a gas-liquid two-phase flow in a horizontal pipeline. In the tests on laboratory installation two ²⁴¹Am radioactive sources and scintillation probes with NaI(Tl) crystals have been used. The experimental set-up allows recording of stochastic signals, which describe instantaneous content of the stream in the particular cross-section of the flow mixture. The analyses of these signals by statistical methods allow to determine the mean velocity of the gas phase. Meanwhile, the selected features of signals provided by the absorption set, can be applied to recognition of the structure of the flow. In this work such three structures of air-water flow as: plug, bubble, and transitional plug – bubble one were considered. The recorded raw signals were analyzed in time domain and several features were extracted. It was found that following features of signals as the mean, standard deviation, root mean square (RMS), variance and 4^th moment are most useful to recognize the structure of the flow.