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Abstract: V diplomskem delu se je analiziralo aerodinamično obnašanje preobraznega krila pri različnih vpadnih kotih. S programom ANSYS FLUENT so bile izračunane spremembe koeficienta upora in vzgona ter primerjane pri pogojih lebdenja in križarjenja. Dodatno je bil preučen vpliv gostote računske mreže na koeficiente vzgona, pri čemer je bila določena optimalna velikost mreže – 1,7 milijona elementov, pri kateri so se vrednosti stabilizirale. Na tej osnovi so bili analizirani različni vpadni koti in spremljane so bile spremembe aerodinamičnih lastnosti. Ugotovljeno je bilo, da režim letenja vpliva minimalno, medtem ko ima največji vpliv vpadni kot (preboj pri 14°). Rezultati so se stabilizirali pri 1,7 milijona elementov mreže in so sledili trendom analitičnega izračuna ob ohranjeni stalni razliki.
Keywords: preobrazno krilo, ANSYS Fluent, vpadni kot, upor, vzgon
Published in DKUM: 09.10.2025; Views: 0; Downloads: 18
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Abstract: V diplomskem delu je bila izvedena primerjava učinkovitosti športnih vesel s pomočjo simulacij računalniške dinamike tekočin. Kot glavni pokazatelj učinkovitosti vesla je bila upoštevana sila, ki deluje na veslo pri določeni hitrosti zaveslaja v smeri plovbe. Za lažjo primerjavo je bila pri vseh analiziranih vrstah vesel uporabljena enaka hitrost zaveslaja. Simulacije so bile opravljene v računskem volumnu ob uporabi robnih pogojev, s katerimi so bili simulirani realni pogoji pri športnem veslanju. Poleg rezultatov simulacij diplomsko delo vključuje tudi opis modeliranja, analizo kakovosti računskega območja in predstavitev uporabljenih robnih pogojev. Rezultati simulacije kažejo, da so najučinkovitejše oblike vesel vesla tipa »sekira«, kar je skladno z njihovo pogosto uporabo v praksi. Kot najuspešnejša se je izkazala oblika Sekira 2v3, vendar so razlike v učinkovitosti med vsemi tremi izvedbami lopatice tipa »sekira« zelo majhne in praktično zanemarljive. To pomeni, da vse analizirane izvedbe tega tipa dosegajo podobno visoko raven potisne učinkovitosti.
Keywords: računalniška dinamika tekočin (RDT), numerična analiza, rotirajoča domena, športno veslanje, učinkovitost vesla
Published in DKUM: 25.09.2025; Views: 0; Downloads: 13
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Abstract: The International Fluid Power Conferences are a two day event, intended for all those professionally-involved with hydraulic or pneumatic power devices and for all those, wishing to be informed about the ‘state of the art’, new findings and innovations within the field of hydraulics and pneumatics. All papers included in the conference program are reviewed and collected in the conference proceedings. The gathering of experts at this conference in Maribor has been a tradition since 1995, and is organised by the Faculty of Mechanical Engineering at the University of Maribor, in Slovenia. Fluid Power conferences are organised every second year and cover those principal technical events within the field of fluid power technologies in Slovenia, and throughout this region of Europe. This year's conference FT2025 is taking place on the 17th and 18th September in Maribor, at Congress centre Habakuk.
Keywords: international conference, fluid power, science and profession, inovations, achievements
Published in DKUM: 16.09.2025; Views: 0; Downloads: 78
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Abstract: Cavitation is the phenomenon of fluid evaporation in hydraulic systems, which occurs due to a pressure drop below the value of the vapor pressure. For numerical modelling of this generally undesirable phenomenon, which is often associated with material damage (erosion), there are various mathematical vapor transfer models that have been validated in the past. There are different approaches to predicting cavitation erosion, which have mostly been experimental in the past. Recently various numerical models have been developed with the development of numerical simulations. They describe the phenomenon of cavitation erosion based on different theoretical considerations, such as Pressure wave hypothesis, Microjet hypothesis, or a combination of both. In the present paper, an analysis of the Schnerr-Sauer transport cavitation model was used, upgraded with an erosive potential energy model based on pressure wave hypothesis for cavitation erosion prediction. The extended numerical model has been applied to the case of a radial divergent test section in three different mathematical formulations. The results of simulation were compared and validated to experimental work performed by other authors. The study shows that the distribution of surface accumulated energy agrees with the experimental results, although certain differences exist between formulations. The applied method appears to be appropriate for further use, and to be extended to materials response modelling in the future.
Keywords: kavitacija, erozija, erozivna potencialna energija, numerične simulacije, cavitation, erosion, erosive potential energy, numerical simulation
Published in DKUM: 26.03.2025; Views: 0; Downloads: 7
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Abstract: Skripta obravnava hidroenergetske sisteme. V uvodu so podane temeljne značilnosti oskrbe z energijo v Sloveniji, nato so predstavljeni obnovljivi viri energije in hidroenergija. Temu sledita poglavji o hidrologiji in hidroelektrarnah. V slednjem je podana osnovna razdelitev hidroelektrarn in predstavljen način njihovega delovanja. Na integralni ravni so obravnavani tudi energijski parametri vodnih turbin. Ločena poglavja so namenjena obravnavi konvencionalnih vodnih turbin in njihovih obratovalnih karakteristik. Zadnje poglavje obravnava pojav kavitacije v vodnih turbinah. Definirane so pojavne oblike glede na vrsto vodne turbine in vpliv tega pojava na integralne obratovalne karakteristike.
Keywords: obnovljivi viri energije, hidroelektrarne, vodna turbina, obratovalne karakteristike, kavitacija
Published in DKUM: 22.11.2024; Views: 0; Downloads: 33
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