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Title:NUMERICAL MODELING OF THE IMMERSION QUENCHING PROCESS USING AN EULERIAN MULTI-FLUID MODELING APPROACH
Authors:ID Kopun, Rok (Author)
ID Škerget, Leopold (Mentor) More about this mentor... New window
ID HRIBERŠEK, Matjaž (Comentor)
Files:.pdf DR_Kopun_Rok_2014.pdf (6,07 MB)
MD5: C77ADCB1C724921D276D5E5CA0447383
 
Language:English
Work type:Dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FS - Faculty of Mechanical Engineering
Abstract:Optimization of heat transfer characteristics in automotive industries is one of the more important factors leading to reductions in fuel consumption and lower emissions values. Efficient heat treatment techniques, like immersion quenching, have been introduced in order to replace heavier metals with lower weight alloys (aluminum), which results in vehicle weight reduction and consequently improved fuel consumption and emission values. Immersion quenching is one of the more important heat treatment techniques introduced in automotive industries, where heat transfer plays a vital role in determining the structure and mechanical properties of the material (e.g. the cylinder head). This presented PhD thesis deals with the development and validation of improved computational methodology in order to simulate the heat transfer characteristics of the immersion quenching cooling process, as implemented within the commercial computational fluid dynamics (CFD) code AVL FIRE®. The boiling phase change process between the heated part and a sub-cooled liquid domain is handled by using the Eulerian multi-fluid modeling approach, where each phase is treated as interpenetrating continua. While for the fluid domain mass, momentum and energy equations are solved within the content of the multi-fluid modeling approach, where only the energy equation is solved to predict the thermal field within the solid region. Result comparisons between the measurements and corresponding numerical simulations using the variable Leidenfrost temperature with additional interfacial forces showed very good agreement. The comparisons were performed on an aluminum step-plate test piece with different thicknesses along its length and on a simplified aluminum cylinder head structure. The specimens were submerged within the liquid domain at different pool temperatures and different solid part orientations, where the solid temperature histories predicted by the numerical model correlated very well with the provided measurement data.
Keywords:CFD, Multiphase boiling, heat transfer, quenching, Leidenfrost temperature, interfacial forces, results comparison
Place of publishing:[Maribor]
Publisher:[R. Kopun]
Year of publishing:2014
PID:20.500.12556/DKUM-44875 New window
UDC:519.6:536.242:[004:532.5](043.3)
COBISS.SI-ID:18027030 New window
NUK URN:URN:SI:UM:DK:SVEAECCU
Publication date in DKUM:14.08.2014
Views:2367
Downloads:349
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FS
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Secondary language

Language:Slovenian
Title:NUMERIČNO MODELIRANJE PROCESA GAŠENJA Z UPORABO EULERJEVEGA VEČFAZNEGA PRISTOPA
Abstract:Optimizacija prenosa toplote v avtomobilistični industriji je eden izmed ključnih dejavnikov, ki pripomore k zmanjšanju porabe goriva in znižanju emisij izpustnih sistemov. Učinkovite metode toplotne obdelave, kot je proces gašenja, se uporabljajo pri nadomestitvi delov iz težjih kovin z lažjimi zlitinami (npr. aluminijastimi), kar pripomore k zmanjšanju teže vozila in posledično vpliva na znižanje porabe goriva in emisijskih vrednosti. Proces gašenja s potapljanjem v tekoči fazi je tako eden izmed najpomembnejših industrijskih procesov v avtomobilistični industriji, saj igra prenos toplote ključno vlogo pri določitvi strukturne in mehanske lastnosti materiala (npr. glave motorja). Doktorska disertacija obravnava razvoj in validacijo izboljšanega numeričnega modela prenosa toplote pri procesu gašenja s potapljanjem v tekočini implementiranega v komercialni program računalniške dinamike tekočin (CFD) AVL FIRE®. Prenos toplote pri procesu gašenja med surovcem in pregreto tekočo fazo se obravnava s pomočjo Eulerjevega večfaznega pristopa, kjer obravnavamo vsako fazo kot samostojno in neodvisno. Masna, gibalna in energijska enačba se rešujejo neodvisno le za tekočo domeno, medtem ko se za trdnino rešuje le energijska enačba. Primerjava rezultatov eksperimentalnih meritev in pripadajočih numeričnih simulacij z uporabo spreminjajoče se Leidenfrost temperaturne predpostavke skupaj z upoštevanjem dodatnih medfaznih sil je pokazala zelo dobro ujemanje. Primerjavo smo izvedli na testnem aluminijastem preizkušancu z različnimi odebelitvami vzdolž dolžine in poenostavljeni aluminijasti glavi motorja. Preizkušanca sta bila potopljena v tekočo fazo s različnimi temperaturami in različnimi orientacijami potopitve, pri čemer se numerična temperaturna napoved hlajenja strukture po celotnem volumnu med procesom gašenja zelo dobro ujema z eksperimentalno dobljenimi vrednostmi.
Keywords:CFD, večfazno vrenje, prenos toplote, gašenje, Leidenfrost temperatura, medfazne sile, primerjava rezultatov


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