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Naslov:CFD simulacija vbrizgavanja zraka v aeracijski bazen centralne čistilne naprave Ptuj
Avtorji:ID Mlakar, Matija (Avtor)
ID Hriberšek, Matjaž (Mentor) Več o mentorju... Novo okno
ID Zadravec, Matej (Komentor)
Datoteke:.pdf UNI_Mlakar_Matija_2014.pdf (3,95 MB)
MD5: C13F11476D128149164CAF07741B14C4
 
Jezik:Slovenski jezik
Vrsta gradiva:Diplomsko delo/naloga
Tipologija:2.11 - Diplomsko delo
Organizacija:FS - Fakulteta za strojništvo
Opis:Pred začetkom izdelave diplomske naloge sem v podjetju na glavni cevovod namestili merilec pretoka, s katerim sem v tabelo zbral dejanske vrednosti masnega pretoka plinske faze v sistem pri različnih obremenitvah puhal. Do takrat so bile poznane samo teoretične vrednosti podane s strani proizvajalca puhal. Simulacija je bila narejena za tri pretoke, maksimalnega 2,472kg/s, srednjega 1,388kg/s in najmanjšega 0,88kg/s. Nato je bil v programu Ansys 15.0 zmodeliran celoten bazen (52,80m X 18,00m X 4,66m), prav tako sta bila zmodelirana dva podporna stebra za most, dva cevovoda za črpalki in dekanter. Nato je sledila mreža, katera je bila namensko zgoščena pod blazinami za vbrizgavanje zraka za večjo natančnost pri določanju hitrostnih polj in vsebuje 4.385.013 vozlišč, torej 14.752.784 elementov. Nato so sledile fizikalne nastavitve v programu Ansys 15.0. treba je omeniti, da je celotna simulacija temelji na Euler-Euler pristopu in ne na Euler – Lagrange. Vse fizikalne nastavitve si sledijo v kronološkem zaporedju, na začetku je bil izbran tip analize »časovno odvisna analiza«, kjer je bilo izbranih 300 sekund s časovnim korakom 0,1s. Potem so sledile nastavitve sistema, kjer sem določil fizikalne nastavitve posameznih faz, ter nastavitve obeh faz kot par. Ko so bile vnesene vse fizikalne nastavitve, je bilo potrebno določiti definirana območja v sistemu. Tako so bile za vnos plinske faze v sistem izbrane blazine, katerih je 72. Simulacija je bila narejena za tri pretoke, ki so bili pridobljeni s namestitvijo merilca. Na gladini vode je bilo potrebno določiti pogoje odplinjevanja disperzne faze. Vse ostale nastavitve so bile narejene v zavihku nedefinirana območja, kjer sem vsem oviram in stenam v sistemu predpisal, da je hitrost zvezne faze enaka 0m/s, torej ni dovoljen zdrs. Za zvezno fazo pa stene in ovire predstavljajo površino s prostim zdrsom. Pri nadzorovanju konvergence sem si pomagal s dodano funkcijo in sicer volumski delež zraka, iz katere je bilo razvidno, da je bila izbira 3000 časovnih korakov pravilna, saj se prične plinska faza v sistemu stabilizirati. Ko je bila simulacija končana sem primerjal rezultate vseh treh pretokov. Volumski delež plinske faze je prikazan po prerezih bazena. Posebej zanimiv je volumski delež plinske faze od enega metra navzgor. Ugotovil sem, da se volumski delež plinske faze najbolj enakomerno porazdeli prav pri pretoku 1,388kg/s v katerem obratuje Centralna čistilna naprava Ptuj. Prav tako je narejen graf povprečnih vrednosti volumskega deleža plinske faze v sistemu in graf maksimalnih vrednosti volumskega deleža plinske faze v sistemu. Zanimivo je, da se maksimalne vrednosti volumskega deleža plinske faze pojavijo v območij največje turbolence. Druga naloga te diplomske naloge pa je bila preučiti posedanje delcev v bazenu. Iz grafa posedanja delcev sem določil povprečno hitrost posedanja delcev. Nato sem v programu Ansys omejil hitrost zvezne faze tako, da je bilo mogoče razbrati ali so hitrosti manjše ali večje. Če so bile večje od predpisane hitrosti posedanja, tam do posedanja ni prišlo. Ko sem se osredotočil na samo par blazin, je bilo razvidno, da v sistemu lahko prihaja do popolnega posedanja ali pa do delnega posedanja delcev pod blazinami. Ko je bil narejen prečni prerez bazena pa je bilo razvidno, da prihaja do delnega posedanja ponovno v območjih največje turbolence. Končne ugotovitve diplomske naloge so bile naslednje, čeprav v bazenu prihaja do posedanja delcev je količina teh dovolj majhna, da lahko Centralna čistilna naprava Ptuj obratuje ne moteno. Ugotovitev, da se volumski delež plinske faze najbolj enakomerno razporedi pri točno tem pretoku pri katerem deluje Ptujska čistilna naprava. S odkritjem območij največjih koncentracij zraka smo na predstavitvi v podjetju ugotovili, da se nahaja sonda za merjenje kisika ravno v tem območju in bo v prihodnosti premeščena na mesto, kjer ne prihaja do maksimalnih vrednosti volumskega deleža plinske faze.
Ključne besede:CFD simulacija, čistilna naprava, vbrizgavanje zraka, razporeditev plinske faze, posedanje
Kraj izida:Maribor
Založnik:[M. Mlakar]
Leto izida:2014
PID:20.500.12556/DKUM-45285 Novo okno
UDK:[532.5:004]:533.4:621.64.057(043.2)
COBISS.SI-ID:18397206 Novo okno
NUK URN:URN:SI:UM:DK:WQUDRSFQ
Datum objave v DKUM:20.10.2014
Število ogledov:2009
Število prenosov:228
Metapodatki:XML DC-XML DC-RDF
Področja:KTFMB - FS
:
MLAKAR, Matija, 2014, CFD simulacija vbrizgavanja zraka v aeracijski bazen centralne čistilne naprave Ptuj [na spletu]. Diplomsko delo. Maribor : M. Mlakar. [Dostopano 22 april 2025]. Pridobljeno s: https://dk.um.si/IzpisGradiva.php?lang=slv&id=45285
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Sekundarni jezik

Jezik:Angleški jezik
Naslov:CFD simulation of the injection of air into the aeration pool of central wastewater treatment plant Ptuj
Opis:Before I started writing my thesis I had a flow meter installed on to the main air pipeline. Data was collected in to the table of the actual values of the mass flow rate of the gas phase in the system at different loads of the blowers. Until that time, only theoretical values given by the manufacturer of blowers were known. The simulation was conducted for three streams, the maximum 2,472kg / s, middle 1,388kg / s and a minimum 0,88kg / s. Then the pool (52,80m X 18,00m X 4,66m) was modeled in the program Ansys 15.0 I have also modeled two support pillars for the bridge, two pipeline pump and a »decanter«. Then followed a grid, which has been specially concentrated under the pillows for injection of air, for greater accuracy in determining the velocity fields and volume fractions. The grid contains 4,385,013 nodes, that is 14,752,784 elements. Then followed the physical settings in Ansys 15.0. It should be noted that the whole simulation is based on the Euler-Euler approach and not the Euler – Lagrange approach. All physical setting are chosen in a chronological order. At the beginning I choose the type of analysis "time-dependent analysis", which lasted 300 seconds with a time step of 0.1sec. Then followed the system settings where I set the physical settings of individual phases and settings of the two phases as a couple. When all physical setting were set, it was necessary to establish the defined areas of the system. Gas phase was set to enter the system through selected cushion, and there are 72 of them. Simulation was conducted for the three flow rates, which were obtained by installing the flow meter. On the surface of the water, it was necessary to determine degassing conditions the disperse phase. All other settings were made in the tab« undefined area« where all other obstacles and walls in the system were prescribed »no slip wall for the continuous phase«, which means the speed of the water on the walls is zero. For continuous phase, the walls and barriers represent an area with »free slip wall«, which means the speed of the dispersed phase is greater than zero. In the case of controlling the convergence I helped my self with an additional function, called » air volume fraction«, from which it was apparent that the choice of 3000 time steps was correct, since the gas phase in the system starts to stabilize. When the simulation was completed, I compared the results of all three flows. The volume fraction of the gas phase is shown by the cross sections of the pool. Particularly interesting is the volume fraction of the gas phase from one meter upwards. I found that the volume of the gas phase is most evenly distributed in the flow 1,388kg / s under which Central Wastewater Treatment Plant Ptuj operates. I also made a graph of the average value of the volume fraction of the gas phase in the system, and a graph of the maximum value of the volume fraction of the gas phase in the system. It is interesting, that the maximum value of the volume fraction of the gas phase occur in the areas of maximum turbulence. The second task of this thesis was to examine the settling of particles in the pool., I set an average settling velocity of particles from the graph of the settling particles. Then I limited the speed of the continuous phase in the program Ansys 15.0 so that it was possible to figure out whether the speed is less than or greater than the settling sped of the particles. If the speed was larger than the prescribed settling speed, the settling would not occur. When I focused on just a couple of cushions, it was clear that a complete or partial settling of particles can occur under the pillows. When the cross-sectional view of the pool has been made, it was clear that there is a partial settling of the particles in the area of maximum turbulence. Final conclusions of the thesis are as follows, although the settling of the particles occurs in the pool, the amount of settled particles is small enough that the Central Wastewater Treatment Plant Ptuj operation is not disturbed. I came to the conclusi
Ključne besede:CFD simulation, wastewater treatment plant, air injection, the distribution of the gas phase, settling


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