Benjamin Bizjan (Author), Marko Hočevar (Author), Sabina Kolbl (Author), Gašper Rak (Author)

Abstract

Aerirani tokovi predstavljajo izziv in priložnost pri merjenju proste vodne površine. V tej študiji je bila naprava LIDAR uporabljena za merjenje razdalje od senzorja naprave do površine vodnega stolpca, izpostavljenega različnim stopnjam prezračevanja, medtem ko so bile referenčne meritve opravljene s slikanjem z veliko hitrostjo. Različni pogoji prezračevanja so bili ustvarjeni s spreminjanjem hitrosti pretoka zraka, ki se dovaja v tekočino, in z uporabo perforiranih plošč z različno razporeditvijo lukenj. Pokazalo se je, da je naprava LIDAR izmerila višino gladine pod vidno gladino vode. Merilna napaka metode LIDAR je v veliki meri odvisna od prostorninskega deleža zraka v vodi in je bila najmanjša pri približno 0,1 prostorninskega deleža zraka. Napaka linearno narašča do zelo visokega volumskega deleža zraka (tj. nad 0,55), metoda LIDAR pa se slabo obnese tudi v vodi brez zraka. Čeprav je merilna negotovost metode LIDAR v območj u prezračevane vode vsaj za red velikosti večja kot pri merjenju suhih trdnih površin, je metoda primerna za merjenje prostih površin v pogojih nizke do zmerne ozračenosti, ki ne povzročajo prekomernega penjenja.

Keywords

aerated flow;free surface;laser scanning;LIDAR;non-stationary surface;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UL FGG - Faculty of Civil and Geodetic Engineering
UDC: 531.717:528.8.042
COBISS: 177070595 Link will open in a new window
ISSN: 0955-5986
Views: 143
Downloads: 33
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Other data

Secondary language: Slovenian
Secondary abstract: Aerated flows pose both challenges and opportunities in the measurement of free water surface. In this study, an amplitude-modulated continuous wave scanning LIDAR device was used to measure a distance from the device sensor to the water column surface subjected to different degrees of aeration, while reference measurements were performed by high-speed imaging. Different aeration conditions were generated by variation of the air flow rate supplied to the liquid and by using perforated plates with different hole arrangements. The LIDAR device was shown to produce level readings consistently below visible water levels. The measurement error of the LIDAR method is largely determined by the volume fraction of air in water and was lowest at about 0.1 air volume fraction. The error increases linearly until a very high air volume fraction (i.e., above 0.55), while the LIDAR method also performs poorly in unaerated water. Although the measurement uncertainty of L IDAR in the range of aerated water is by at least an order of magnitude higher than in the case of measuring dry solid surfaces, the method is viable for free surface measurement under low to moderate aeration conditions that don’t produce excessive foaming.
Secondary keywords: aeriran tok;prosta gladina;lasersko skeniranje;LIDAR;nestacionarna gladina;
Type (COBISS): Article
Pages: str. 1-8
Issue: ǂVol. ǂ95, [article no.] 102502
Chronology: Feb. 2024
DOI: 10.1016/j.flowmeasinst.2023.102502
ID: 21843122