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Topološka struktura vodne gladine na sotočju pri deročem toku : doktorska disertacija
Rak, Gašper (Author), Steinman, Franci (Mentor) More about this mentor... This link opens in a new window, Hočevar, Marko (Thesis defence commission member), Žagar, Dušan (Thesis defence commission member), Jecl, Renata (Thesis defence commission member), Klasinc, Roman (Thesis defence commission member)

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Abstract
Z eksperimentalno raziskavo smo analizirali hidrodinamične razmere na območju asimetričnega pravokotnega sotočja pri deročih dotokih z višjimi vrednostmi Froudovih števil (2 %Fr % 12), pri katerih se pojavi dinamično, razpenjeno stoječe valovanje. Da bi fenomenološko določili sovisnosti med integralnimi parametri vodnih tokov in lastnostmi stoječega valovanja na območju sotočja, smo najprej izvedli meritve topografije vodne gladine za 168 kombinacij dveh tokov (scenarijev na sotočju). Za meritve prečnega poteka gladine smo uporabili lasersko skeniranje, ki kot sodobna brezkontaktna merilna tehnika omogoča meritve pojavov z veliko dinamiko ter prostorsko in časovno ločljivostjo. Kljub razširjenosti laserskega skeniranja pa to za zajem topografije gladine čiste vode, brez dodanih primesi, plovcev ipd., še ni bilo uporabljeno. Zaradi narave interakcije med laserskimi žarki in gladino vodnih teles smo v prvem delu raziskali, ali % in pod kakšnimi pogoji % je lasersko skeniranje uporabno za zajem topografije vodne gladine. S primerjavo teh meritev z referenčnimi vrednostmi drugačnih merilnih tehnik smo potrdili prvo hipotezo, da je % tako pri laboratorijskih kot tudi terenskih meritvah % mogoče z laserskim skeniranjem zelo natančno zajeti potek vodne gladine predvsem razburkanih, dvofaznih tokov z veliko vertikalno dinamiko, torej kompleksnejših hidravličnih pojavov, kjer so druge merilne metode manj uspešne oziroma neuporabne. V drugem delu smo uporabili sistematične meritve vodne gladine po prerezih na območju sotočja pri vseh scenarijih za določitev srednjega poteka gladine in z izdelavo mrežnih modelov izdelali topografije stoječega valovanja. S tem smo pridobili pomembno podlago za analizo topologije sotočja. Rezultati so potrdili drugo hipotezo, da je mogoče zapisati fenomenološke zveze med vhodnimi, geometrijskimi in hidravličnimi parametri tokov ter glavnimi značilnostmi vodnih struktur, ki se pojavljajo na sotočjih pri deročem toku. Nove fenomenološko izpeljane enačbe, ki opisujejo prečni in vzdolžni potek gladin ter tudi višino fluktuacij, opišejo topologijo vodne gladine v ustrezni meri ter tako prinašajo informacije o procesih in njihovi magnitudi, ki so pomembne za inženirsko prakso.

Language:Slovenian
Keywords:grajeno okolje, gradbeništvo, disertacije, sotočje, deroči tok, eksperimentalno hidravlično modeliranje, topologija, stoječi valovi, lasersko skeniranje
Work type:Doctoral dissertation (mb31)
Tipology:2.08 - Doctoral Dissertation
Organization:FGG - Faculty of Civil and Geodetic Engineering
Year:2017
Publisher:[G. Rak]
UDC:515.1:519.87:528.8:532.5(043)
COBISS.SI-ID:8168801 Link is opened in a new window
License:CC BY-NC 4.0
This work is available under this license: Creative Commons Attribution Non-Commercial 4.0 International
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Downloads:403
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Secondary language

Language:English
Title:Water surface topology of supercritical confluence flow : doctoral thesis
Abstract:
We used an experimental study to analyse the hydrodynamic conditions at an asymmetric right-angled confluence with incoming supercritical flow at higher Froude numbers (2 % Fr % 12), where dynamic, foamed standing waves form. For a phenomenological determination of the relations between the integral parameters of water flows and the characteristics of standing waves at the confluence area, we first measured water surface topographies for 168 combinations of two flows (i.e. scenarios at the confluence). Laser scanning was used to measure transversal water surface profiles, which, as a modern non-contact measurement method, allows for measurements of the phenomena with high dynamics as well as high spatial and temporal resolution. Despite its widespread use, laser scanning has not yet been used to acquire clean water topography, without any additional substances, floats, etc. Given the nature of interactions between laser beams and water body surfaces, we investigated, in the first part, the conditions under which laser scanning can be applied in water surface topography measurements. Comparing these measurements with the reference values of other measurement methods supported the first hypothesis that, both in laboratory and field measurements, laser scanning allows for a precise determination of water levels, particularly of turbulent, two-phase flows with high vertical fluctuations, i.e. complex hydraulic phenomena where other measurement methods are less successful or unsuited. In the second part we used the systematically measured water surfaces in the individual cross-sections in the confluence area for all the scenarios for determining the water level%s mean value, and by producing mesh models we constructed the topographies of standing waves. This provided an important basis for analysing confluence topography. The results supported the second hypothesis, i.e. that it is possible to record phenomenological relations between input, geometrical, and hydraulic flow parameters and the main characteristics of flow structures forming at confluences with incoming supercritical flows. The new, phenomenologically-derived equations modelling the formation of surfaces in the transversal and longitudinal directions and the fluctuation level describe the water surface topology to a satisfying degree, resulting in important information about the processes and their magnitude for engineering workWe used an experimental study to analyse the hydrodynamic conditions at an asymmetric right-angled confluence with incoming supercritical flow at higher Froude numbers (2 % Fr % 12), where dynamic, foamed standing waves form. For a phenomenological determination of the relations between the integral parameters of water flows and the characteristics of standing waves at the confluence area, we first measured water surface topographies for 168 combinations of two flows (i.e. scenarios at the confluence). Laser scanning was used to measure transversal water surface profiles, which, as a modern non-contact measurement method, allows for measurements of the phenomena with high dynamics as well as high spatial and temporal resolution. Despite its widespread use, laser scanning has not yet been used to acquire clean water topography, without any additional substances, floats, etc. Given the nature of interactions between laser beams and water body surfaces, we investigated, in the first part, the conditions under which laser scanning can be applied in water surface topography measurements. Comparing these measurements with the reference values of other measurement methods supported the first hypothesis that, both in laboratory and field measurements, laser scanning allows for a precise determination of water levels, particularly of turbulent, two-phase flows with high vertical fluctuations, i.e. complex hydraulic phenomena where other measurement methods are less successful or unsuited. In the second part we used the systematically measured water surfaces in the individual cross-sections in the confluence area for all the scenarios for determining the water level%s mean value, and by producing mesh models we constructed the topographies of standing waves. This provided an important basis for analysing confluence topography. The results supported the second hypothesis, i.e. that it is possible to record phenomenological relations between input, geometrical, and hydraulic flow parameters and the main characteristics of flow structures forming at confluences with incoming supercritical flows. The new, phenomenologically-derived equations modelling the formation of surfaces in the transversal and longitudinal directions and the fluctuation level describe the water surface topology to a satisfying degree, resulting in important information about the processes and their magnitude for engineering work

Keywords:building environment, civil engineering, thesis, confluence, supercritical flow, experimental hydraulic modeling, topology, standing waves, laser scanning

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