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Title:Numerična analiza toka tekočine v vtočnem bazenu vertikalnih črpalk
Authors:Škerlavaj, Aljaž (Author)
Škerget, Leopold (Mentor) More about this mentor... New window
Ravnik, Jure (Co-mentor)
Files:.pdf DR_Skerlavaj_Aljaz_2011.pdf (15,75 MB)
 
Language:Slovenian
Work type:Dissertation (m)
Organization:FS - Faculty of Mechanical Engineering
Abstract:Napovedovanje lokacije in intenzitete podvodnih in površinskih vrtincev je zelo pomembno v postopku načrtovanja vtočnih bazenov vertikalnih črpalk, kot na primer v nekaterih sistemih jedrskih elektrarn (v obratovalnih ali nezgodnih stanjih) ali v namakalnih sistemih. Močni podvodni ali površinski vrtinci so nezaželeni zaradi morebitne kavitacije, neenakomernega natoka vode na rotor in sesanja plavin ali zraka z vodne gladine, kar lahko poslabša delovanje črpalke ali celo povzroči njeno odpoved. Lokacijo in intenziteto vrtincev v črpalnih bazenih se navadno ugotavlja eksperimentalno na pomanjšanih modelih vtočnih bazenov. Ker je izdelava modelov in eksperimentalno testiranje drago, lahko pričakujemo, da bodo v prihodnosti numerični izračuni pomagali pri izvedbi eksperimentalnih testov ali pa jih celo nadomestili. V doktorski disertaciji smo testirali možnost napovedovanja toka tekočine v vtočnih bazenih z numeričnim izračunom. Na podlagi primerjave enofaznih numeričnih izračunov in eksperimentalnih podatkov smo iskali primeren turbulentni model za takšen tok tekočine. Primerjava je bila izvedena v treh korakih. V prvem delu doktorske disertacije smo obravnavali numerični izračun talnega vrtinca v vtočnem bazenu. V drugem delu disertacije smo izvedli numerični izračun površinskega vrtinca. Odkrili smo, da je najprimernejši turbulentni model za simulacijo talnega in tudi površinskega vrtinca model prilagodljivih skal velikosti (SAS) s korekcijo ukrivljenosti (CC). V drugem delu disertacije smo določali dolžino zračnega jedra površinskih vrtincev na osnovi predpostavke o Burgersovem tipu vrtinca. V tretjem delu disertacije smo uporabili model SAS-CC za numerični izračun laboratorijskega modela vtočnega bazena. Na podlagi primerjave z eksperimentalnimi rezultati glede oblike površinskih vrtincev in napovedanega sesanja zraka z vodne gladine smo potrdili, da je model SAS-CC primerna izbira za numerične izračune vtočnih bazenov.
Keywords:turbulentni model, simulacija, numerični izračun, talni vrtinec, površinski vrtinec, črpalni bazen, SAS, LES, SST, korekcija ukrivljenosti, sesanje zraka
Year of publishing:2011
Publisher:A. Škerlavaj]
Source:[Maribor
UDC:532.517.4:621.5(043.3)
COBISS_ID:259586816 Link is opened in a new window
NUK URN:URN:SI:UM:DK:JMGS3AMA
Views:2011
Downloads:138
Metadata:XML RDF-CHPDL DC-XML DC-RDF
Categories:KTFMB - FS
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Secondary language

Language:English
Title:Numerical Analysis of Fluid Flow in a Pump Sump
Abstract:Prediction of location and strength of subsurface and free-surface vortices is important in the design of pump intake structures with vertical pumps, such as in several systems of nuclear power plants (in operating or post-accident conditions), or in the irrigation systems. Strong subsurface or free-surface vortices are undesired as the cavitation or unequal loading on the runner may appear, or the trash debris or air can be sucked to the impeller eye, which can deteriorate the pump performance or cause the pump failure. The location and strength of pump intake vortices is usually determined in laboratories on downscaled models. Constructing a pump sump model and experimental testing is expensive, therefore numerical simulations are expected to help or even replace the experimental testing in the future. In this thesis the feasibility study has been conducted to assess the single-phase computational fluid dynamics (CFD) simulation of water flow in pump intakes. More specifically, by using a single phase simulation, we searched for a suitable turbulence model for such flow by comparing the CFD vortex prediction to experimental data. The comparison was done in three steps. In the first part of the thesis a floor vortex simulation in a pressurized pump sump was conducted. In the second part a free-surface vortex model was simulated. It was discovered that the scale adaptive simulation with the curvature correction option (SAS-CC) was the best choice for the subsurface and the free-surface vortex simulation. In the second part a method for the free-surface vortex gas core length prediction was based on the Burgers vortex type assumption. In the third part of the thesis the SAS-CC model simulation of the pump intake laboratory model was conducted. Based on the comparison of the calculated free-surface vortex shape and the predicted gas entrainment with the experimental results it was confirmed that the SAS-CC model is a proper choice for the pump intake CFD simulation.
Keywords:turbulence model, simulation, CFD, floor vortex, free-surface vortex, pump intake, pump sump, SAS, LES, SST, curvature correction, gas entrainment


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