scholarly journals Measurement of Gas and Liquid Velocities in an Air-Water Two-Phase Flow using Cross-Correlation of Signals from a Double Senor Hot-Film Probe

2002 ◽  
Author(s):  
B. Gurau ◽  
P. Vassalo ◽  
K. Keller
Keyword(s):  
Cross Correlation ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Hot Film

scholarly journals Time Delay Estimation in Two-Phase Flow Investigation Using theγ-Ray Attenuation Technique

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Robert Hanus ◽  
Marcin Zych ◽  
Leszek Petryka ◽  
Dariusz Świsulski
Keyword(s):  
Time Delay ◽  
Cross Correlation ◽  
Two Phase Flow ◽  
Time Delay Estimation ◽  
Delay Estimation ◽  
Phase Flow ◽  
Two Phase ◽  
Stochastic Signals ◽  
Difference Function ◽  
Combined Methods

Time delay estimation is an important research question having many applications in a range of technologies. Measurement of a two-phase flow in a pipeline or an open channel using radioisotopes is an example of such application. For instance, the determination of velocity of dispersed phase in that case is based on estimation of the time delay between two stochastic signals provided by scintillation probes. The proper analysis of such signals, usually in presence of noise, requires the use of advanced statistical signal processing. In this paper, the simulation studies of time delay estimation were carried out with the use of the following differential methods: average magnitude difference function, and average square difference function and proposed combined methods comprising the above-mentioned differential and cross-correlation functions are presented. Attached simulations have been carried out for models of stochastic signals corresponding to the signals obtained in gamma-ray absorption measurements of gas-liquid flow in a horizontal pipeline. The standard uncertainties of time delay estimations have been determined for each of the methods. Improved metrological properties have been stated in the combined methods in comparison with the classical cross-correlation procedure.

Simulative Study On Liquid/Gas Two–Phase Flow Measurement For Dual–Plane Ultrasonic Transmission–Mode Tomography

2012 ◽  
Author(s):  
Nor Muzakkir Nor Ayob ◽  
Mohd Hafiz Fazalul Rahiman ◽  
Zulkarnay Zakaria ◽  
Sazali Yaacob ◽  
Ruzairi Abdul Rahim ◽  
...  
Keyword(s):  
Flow Measurement ◽  
Cross Correlation ◽  
Two Phase Flow ◽  
Separation Distance ◽  
Correlation Technique ◽  
Phase Flow ◽  
Two Phase ◽  
Transmission Tomography ◽  
Single Plane ◽  
Dual Plane

Kajian simulatif telah dijalankan mengenai penggunaan teknik korelasi–silang untuk ultrasonik transmisi tomografi satah berganda. Teknik ini digunakan untuk membandingkan isyarat dari setiap satah yang masing–masing dinamakan satah–bawah dan satah–atas. Pemisahan jarak antara kedua–dua satah adalah tetap. Hasil dari perbandingan isyarat satah berganda, digabungkan dengan jarak pemisahan yang telah diketahui termasuk kelajuan sistem memproses maklumat, boleh digunakan untuk menganggarkan kelajuan aliran di dalam paip pemprosesan yang hendak diteliti. Penggabungan Ultrasonik Transmisi Tomografi (UTT) dengan teknik pengukuran korelasi–silang dapat memberikan maklumat yang lebih lanjut mengenai aliran jika dibandingkan dengan sistem UTT bersatah tunggal. Diskusi dalam artikel ini lebih memfokuskan kepada nilai min setiap gambar dan pekali korelasi 2D yang akan digunakan untuk mengkorelasikan gambar tomogram antara satah–bawah dan satah–atas. Prinsip pengukuran kelajuan pergerakan gas didalam keadaan gas dan cecair yg bergelembung berdasarkan pada korelasi–silang antara kedua–dua satah juga dijelaskan. Keputusan awal eksperimen menggambarkan kesesuaian kaedah yang dibentangkan di sini. Kata kunci: Korelasi–silang; corak beku; korelasi min; simulasi satah berganda; tomografi transmisi ultrasonik Simulative studies are done on the use of cross–correlation technique based on a dual–plane ultrasonic transmission tomography for liquid and gas two–phase flow measurement. This technique is used to correlate the signals from each sensing area namely downstream plane and upstream plane. Separation distance between both sensing areas is fixed. The result from cross correlating the dual–plane signals, combined with the known separation distance and the system’s acquisition rate is used to estimate the velocity of the flow inside the investigated process column. Combining Ultrasonic Transmission Tomography (UTT) with the cross–correlation flow measurement technique can provide more information on the flow than a single–plane UTT system. This paper focuses on the mean value of the images and the 2D correlation coefficient that is used to cross–correlate the tomogram images between the downstream and upstream plane of the simulated dual–plane ultrasonic transmission tomography system. The principle of measurement for local gas velocity distribution in a bubbly gas/liquid pipe flow based on crosscorrelation of two plane images is also described. Initial experimental results illustrate the feasibility of the method presented here. Key words: Cross–correlation; frozen pattern; mean correlation; dual–plane simulation; ultrasonic transmission tomography

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