Non-intrusive measurements of free-water-surface profiles and fluctuations of turbulent, two-phase flow using 2-D laser scanner

Rak, Gašper (author), Hočevar, Marko (author), Steinman, Franci (author)

For measuring free-water surfaces conventional methods, such as resistance-type probes, U-manometers, point gauges, ultrasonic sensors, etc. are still most commonly used in modern hydro engineering. These methods give accurate results at suitable flow conditions, but are insufficient when the water surface is characterized by turbulence and two-phase flow, with fast dynamics. This paper presents the use of laser scanning as a measurement method for the acquisition of free-water-surface profiles of hydraulic phenomena with turbulent, non-stationary, and non-homogeneous free-surface flows. Results shows that laser scanning can provide accurate measurements of free-water-surface profiles with high spatial and temporal resolution, even in cases of turbulent flows with high vertical fluctuations on the water surface. The comparison with the reference values determined by analysing the images taken with the high-speed camera showed that measurement uncertainty ranges from 5 mm to 10 mm, which is more than an order of magnitude smaller than the range of local vertical water-surface fluctuations. The average profiles, envelopes of vertical water surface fluctuation around the mean value, as well as the construction of complex water surface topography of intensive waving can be determined by processing laser scanning data. The results contribute to the wider use of this non-contact measurement method, which provides important information on water flow properties to many fields of hydro-engineering. The application of 2-D laser scanning for free-water-surface acquisition was conducted in the model of supercritical junction flow, where the development of standing waves leads to the phenomenon of self-aerated flow.

• Language: English
• Keywords: hydrotechnics, laser scanning, turbulent two-phase flow, water surface topography, fluctuations, friction
• Work type: Scientific work
• Typology: 1.01 - Original Scientific Article
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Publication status: Published
• Publication version: Author Accepted Manuscript
• Year: 2020
• Number of pages: Str. 1-14
• Numbering: Letn. , št.
• PID: 20.500.12556/RUL-114375
• UDC: 626/627
• ISSN on article: 0957-0233
• DOI: 10.1088/1361-6501/ab727f
• COBISS.SI-ID: 9074529
• Publication date in RUL: 24.02.2020

Record is a part of a journal

• Title: Measurement science & technology
• Shortened title: Meas. sci. technol.
• Publisher: IOP Publishing
• ISSN: 0957-0233
• COBISS.SI-ID: 6000901

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
• Licensing start date: 24.02.2020

Secondary language

• Language: Slovenian
• Keywords: hidrotehnika, lasersko skeniranje, turbulentni dvo-fazni tok, topografija vodne gladine, fluktuacije

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0180
• Name: Vodarstvo in geotehnika: orodja in metode za analize in simulacije procesov ter razvoj tehnologij.