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Title:Vpliv biogoriv na tokovne pojave v vbrizgalni šobi dizelskega motorja
Authors:Vajda, Blaž (Author)
Kegl, Breda (Mentor) More about this mentor... New window
Škerget, Leopold (Co-mentor)
Žunič, Zoran (Co-mentor)
Files:.pdf DR_Vajda_Blaz_2013.pdf (7,04 MB)
MD5: DC683D219573A4DBE05A7AA26E8C8CFF
 
Language:Slovenian
Work type:Dissertation (m)
Typology:2.08 - Doctoral Dissertation
Organization:FS - Faculty of Mechanical Engineering
Abstract:Vbrizgavanje curka goriva spada na področje dvofaznih tokov, ki obravnava karakteristike curka goriva v odvisnosti od fizikalnih lastnosti, s poudarkom na vbrizgavanju različnih goriv, pod različnimi delovnimi pogoji. Poleg ocene kvalitete tvorbe zmesi je raziskovanje karakteristik curka goriva pomembno tudi za oceno izkoriščenosti zraka v zgorevalni komori in zaradi morebitnega nezaželenega stika goriva s stenami zgorevalne komore. Obstoječi fizikalno-matematični modeli lahko v splošnem relativno natančno popišejo razmere dvofaznega toka. V samih podmodelih so prisotne empirične konstante (vplivni parametri), s pomočjo katerih se uravnavajo karakteristike vbrizganega curka in ki so v osnovi odvisne od lastnosti samega vbrizgalnega sistema, predvsem od geometrije vbrizgalne šobe. V okviru naloge bo vpeljan model, ki bo omogočal obravnavanje karakteristik različnih biogoriv, razmer v šobi in posledice vpliva karakteristik na razvoj, obliko in strukturo curka, kjer bo omogočeno natančnejše analiziranje dvofaznih tokov. Model bo zajemal prenosne enačbe za številsko gostoto parnih mehurčkov, z upoštevanjem fizikalnih procesov nastajanja in izginjanja posameznih mehurčkov, pri različnih oblikah kavitacijskih tokov, hkrati pa bo omogočal še raziskavo vpliva med kapljicami goriva ter obravnavo sil trka z vpeljavo velikostne porazdelitve kapljic goriva. Naloga je razdeljena na eksperimentalni in numerični del. V eksperimentalnem delu so določene in analizirane fizikalne lastnosti uporabljenih goriv, karakteristike procesa vbrizgavanja, s pomočjo hitre kamere pa je bil posnet razvoj curka goriva. V numeričnem delu je prikazan osnovni poenostavljeni fizikalno-matematični model. V disertaciji je pokazano, da je mogoče s spremembo fizikalno-matematičnega modela, ob upoštevanju fizikalnih lastnosti goriva, delovnega režima in karakteristik procesa vbrizgavanja, določiti konstante, ki pri izračunu uravnavajo karakteristike curka goriva. S pomočjo ustreznih izrazov je tako mogoče izraziti empirične vrednosti parametrov in vnaprej napovedati probleme, ki bi se lahko pojavili v dizelskih motorjih z uporabo biogoriv.
Keywords:alternativna goriva, sistem za vbrizgavanje goriva, tokovne razmere v šobi, kavitacija, curek goriva, računalniška dinamika tekočin.
Year of publishing:2013
Publisher:B. Vajda]
Source:[Maribor
UDC:621.436.038:665.753(043.3)
COBISS_ID:268033024 New window
NUK URN:URN:SI:UM:DK:CYAYRSWA
Views:1533
Downloads:172
Metadata:XML RDF-CHPDL DC-XML DC-RDF
Categories:KTFMB - FS
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Secondary language

Language:English
Title:The Influence Of Biofuel Mixtures on Flow Phenomena in Diesel Engine Injectors
Abstract:Fuel spray investigations belong to the field of the two-phase flows witch presents the study of physical fuel property dependent spray characteristics. The research will be focused on different type of fuels under different operating conditions. The investigation of spray development as contributing factor in mixture formation is also very important for the study of processes in internal combustion engine. Existing physical-mathematical model for two phase flows generally gives good results. Several empirical constants are present in sub models and they have significant influence on spray development. They are usually depended on injection system and the geometry of injection nozzle. The improvement of physical-mathematical model including the most influential factors with in the momentum equation for spray development, will enable efficient analysis of spray characteristics of alternative fuels. The model will also include the equations for bubble density and the equation for cavitation occurrence. The parts of equation representing the spray development, formation of bubbles and cavitation will be modelled with the adaptation of knowledge of other authors, where the modified model will be able to predict the spray development more accurately. The work contains both experimental and numerical part. Physical properties of the fuels, characteristics of the fuel injection process and high-speed recordings are described and analysed in the experimental part. The simplified physical-mathematical models is presented in the numerical part. The dissertation shows, that the improvement of standard mathematical model for spray development considering the physical fuel properties, the operating conditions and the injection characteristics enables determination of empirical constants. Additionally the physical-mathematical model can be included. By using of appropriate expressions, the empirical parameters values can be determined and enable predictions of potential problems which could appear in diesel engines during operation with biofuels.
Keywords:alternative fuels, fuel injection system, in nozzle flow, cavitation, fuel spray, Computation Fluid Dynamics


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