1. Analytical, numerical and experimental performance prediction of a model-sized wind turbineMatej Fike, Andrej Predin, Gorazd Hren, Marko Pezdevšek, 2024, original scientific article Abstract: The present work focuses on the comparison of the capabilities of Blade Element Momentum Theory, with and without the high induction factor value model and Computational Fluid Dynamics modelling in relation to experimental measurements of the power coefficient for a model-sized horizontal axial wind turbine. Initially, an analytical investigation was performed to obtain the power coefficient curve. Furthermore, three-dimensional numerical simulations were performed, where a lot of effort was devoted to the preparation of a low y+ structured mesh. Analytical and numerical results of the power coefficient were compared with experimental results, which were obtained with our own conducted experiments in the wind tunnel. The most significant conclusions are that the classic BEM method deviates from measured data in the entire range of tip speed ratios, the BEM method with Spera correction predicts a significantly better agreement with experimental measurements compared to the classic BEM method, especially the part where the power coefficient decreases and finally that CFD computations can accurately predict the performance of wind turbines and compute the flow around an aerofoil of the blade.
Keywords: BEM method, CFD, measurements, wind turbine
Published in DKUM: 06.11.2025; Views: 0; Downloads: 1
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2. Assessing the effects of a hydropower plant basin on fish spawning in an upstream river tributaryGorazd Hren, Andrej Predin, Matej Fike, Marko Pezdevšek, 2024, original scientific article Abstract: This paper presents a combined modeling approach to evaluate the ecological effects on the habitat of an upstream tributary of a river with a series of hydropower plants. The influence is investigated of the last planned hydropower plant to be built, which has a large impact on the river ecosystem. The new hydropower plant basin will affect the tributary with hydropeaking in the upstream basin. A simulation was conducted of spawning conditions for two protected fish species. The analysis combined a hydro-morphological model with a fish module that considers the water depth and velocity necessary for fish reproduction. The different river discharge scenarios were simulated, incorporating the hydropeaking effects of the new hydropower plant basin on the upstream tributary. With the new hydropower plant, sustainable measures are planned to prevent the damaging negative impacts that could lead to the degradation of the river ecosystem and the destruction of the existing ecosystem at the river’s confluence. The results indicate that, after the hydropower plant begins operation, the habitat`s suitability will decrease, and the planned sustainable measures will not provide a fully satisfactory solution.
Keywords: environmental impact, habitat sustainability, hydro-dynamic model
Published in DKUM: 11.04.2025; Views: 0; Downloads: 39
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3. Vizualizacija hidroelektrarne z uporabo Unity 3D : diplomsko deloAleksa Kaličanin, 2024, undergraduate thesis Abstract: Namen diplomskega dela je predstavitev predvidene hidroelektrarne Mokrice na spodnji
Savi v virtualnem okolju s pomočjo programskega orodja Unity. Za vizualizacijo
hidroelektrarne smo uporabili poenostavljen model ustvarjen v sistemu CAD. Prenos
modela v virtualno okolje je izveden s pomočjo standardnih formatov, vmesnika VRML
in Blender. Opisan je večfazni postopek prenosa, kakor tudi proces kreiranja grafičnih
predstavitev materialov in tekstur s pomočjo programa Blender. V virtualno okolje so
vključene animacije in interaktivnost. Virtualno okolje je implementirano na sistemski
opremi za navidezno resničnost z uporabo aktivne opreme za interakcijo in vizualizacijo
v programskem orodju Unity.
Keywords: virtualni prototip, Unity, VRML, Blender
Published in DKUM: 11.02.2025; Views: 0; Downloads: 21
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4. Izdelava parametričnega modela Bankijeve turbine : diplomsko deloŽan Suša, 2024, undergraduate thesis Abstract: Namen zaključnega dela je izdelati generični model Bankijeve turbine v sistemu CAD. V prvem delu zaključnega dela so opisane turbine, ki se uporabljajo v velikih in malih hidroelektrarnah, in osnovne značilnosti sistema CAD. V osrednjem delu je opisan način kreiranja in povezovanja konstrukcijske tabele z vsemi parametri za modeliranje Bankijeve turbine po preračunu iz literature. Zasnovana tabela omogoča izvedbo preračuna glede na vhodne karakteristike turbine, volumski pretok in višino padca ter avtomatsko kreiranje modela turbine iz generičnega modela za izračunane parametre. Za kreiranje modela so uporabljene napredne funkcije sistema CAD.
Keywords: SolidWorks, modeliranje, generični model, Bankijeva turbina.
Published in DKUM: 20.09.2024; Views: 0; Downloads: 49
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5. Cavitation erosion modelling : comparison of different driving pressure approachesLuka Kevorkijan, Marko Pezdevšek, Ignacijo Biluš, Gorazd Hren, 2023, original scientific article Abstract: In this paper we compared different driving pressure approaches to calculate the cavitation potential energy from a source, which is transferred to a surface. The first approach used the reference pressure, the second approach used the pressure calculated at each timestep with no averaging, the third approach used the averaged pressure values from all timesteps included in one shedding cycle, and the last approach used pressure values from the steady state simulations results. The results show that for all formulations the averaged pressure values and steady state pressure values give similar results in terms of mean potential power distribution on the hydrofoil surface as in absolute values. The reference pressure approach gave similar results for the derivative and divergence formulation while for the source term the mean potential power distribution on the hydrofoil surface differs and the maximums were near the leading edge. The approach where we used no pressure averaging gave adequate results in terms of mean potential power distribution but differs from other approaches in absolute values which were considerably lower for all potential power formulations.
Keywords: cavitation, erosion potentional, driving pressure, numerical simulations
Published in DKUM: 21.02.2024; Views: 400; Downloads: 295
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6. Primerjava sistemov CAD (Solidworks in Onshape) pri 3D modeliranju : diplomsko deloJan Gabrijel, 2023, undergraduate thesis Abstract: Programska oprema za računalniško podprto konstruiranje je stalnica pri razvoju izdelkov in ima velik vpliv na različne tehnologije in sisteme proizvodnje v raznovrstnih panogah. Razvoj in uporaba teh sistemov je ključno spremenila tradicionalne metode razvoja izdelkov vse od prototipa do končne proizvodnje. Čeprav se teoretske metode modeliranja ne spreminjajo veliko, je njihov razvoj v zadnjem času predvsem usmerjen na prilagajanje vedno močnejši strojni opremi, kakovosti prikazovanja in predvsem soočanja s številnimi izzivi kot so dostopnost do skupnih podatkovnih baz, komunikacija preko računalniških mrež, težave z verzijami ter stroški strojne opreme in licenciranja.
Novejša programska oprema CAD v oblaku, uporabnikom ponuja novo in drugačno storitev, ki ne zahteva namestitve programske opreme in licenciranje, in je enostavno dosegljiva iz internetnega prikazovalnika. Programska oprema v oblaku na splošno sicer še ne odgovarja na vsa vprašanja, ki se ob pojavljajo ob uporabi, vendar že prinaša nove pristope, ki nakazujejo smernice drugačne uporabe sistemov CAD.
V diplomski nalogi smo na primeru geometrije sklopa parnega stroja primerjali sistema CAD: Solidwoks kot tradicionalni sistem CAD in Onshape kot primer sistema CAD v oblaku. Namen diplomske naloge je uporabniška izkušnja dveh programskih sistemov CAD na enakem izdelku katere rezultat so številni dejavniki, ki jih je potrebno upoštevati. Ugotovimo lahko, da je uporabniška izkušnja zelo podobna, a je prednost, ob zagotovljeni varnosti podatkov na strani oblačnih storitev.
Keywords: sistemi CAD, modeliranje, računalništvo v oblaku
Published in DKUM: 16.01.2024; Views: 389; Downloads: 32
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7. Lift and drag coefficients for different magnus rotor typesMarko Pezdevšek, 2019, original scientific article Abstract: In this paper, the results of numerical simulations for various Magnus rotor configurations are presented. For each configuration, a blocked structured mesh was designed in ICEM CFD. Numerical simulations were conducted using Ansys CFX. The influence of the aspect ratio on the lift and drag coefficients depending on the speed ratio was investigated, as was the influence of endplates on a Magnus rotor. From the obtained results, it was concluded that adding endplates to a Magnus rotor increases the lift and drag coefficients.
Keywords: Magnus effect, lift coefficient, drag coefficient, Ansys CFX, endplates, aspect ratio
Published in DKUM: 05.12.2023; Views: 408; Downloads: 92
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8. Influence of Numerical Mesh Type on Airfoil Aerodynamic CharacteristicsMarko Pezdevšek, Matej Fike, Andrej Predin, Gorazd Hren, 2019, published scientific conference contribution Abstract: In this paper, we will examine how different mesh types affect the aerodynamic characteristic of an airfoil. The airfoil used for this paper was the NREL S809. Three different mesh types were created, a blocked structured mesh, an unstructured mesh and a hybrid mesh containing a blocked structured mesh near the surface of the airfoil and an unstructured mesh on the outside perimeter. Steady state simulations were performed for angles of attack between 0°and 22°. Lift and drag coefficient for all created meshes were compared to experimental results from literature. From angles of attack between 2° and 8° all three meshes predict similar lift and drag coefficients. We encountered problems with convergence for the unstructured mesh at angles of attack higher than 8°. Structured and hybrid mesh had similar lift and drag coefficients across all angles of attack.
Keywords: computational fluid dynamics, NREL S809, structured mesh, unstructured mesh, hybrid mesh
Published in DKUM: 04.12.2023; Views: 361; Downloads: 49
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9. Experimental and Numerical Research of Micro Wind Turbine for Low Wind SpeedsMatej Fike, Marko Pezdevšek, Andrej Predin, Gorazd Hren, 2019, published scientific conference contribution Abstract: In this paper, experimental and numerical study of micro wind turbine for low wind speeds is presented. Numerical simulations were performed for two turbines with different blades at various wind speeds. The first geometry was NTNU turbine and the second was modified NTNU turbine with shorter blades. Results from the numerical study showed that more efficient with higher power coefficient is turbine with modified blades.
Keywords: wind turbine, NREL S826, CFD, power coefficient, structured mesh
Published in DKUM: 04.12.2023; Views: 301; Downloads: 48
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10. Lost Energy of Water Spilled over Hydropower DamsAndrej Predin, Matej Fike, Marko Pezdevšek, Gorazd Hren, 2021, original scientific article Abstract: The present paper presents a view of water spilled over hydropower plants as an energy loss. In the current climate conditions, flood events are becoming more frequent due to human impact on the environment; water spills are also more frequent, which means more and more energy is lost. How much water is spilled and, consequently, how much energy is lost is shown in the present article on the chain of power plants on the Sava River in the five years from 2015 to 2019. An analytical assessment of the current situation in the lock was carried out, which showed that the available water through the locks could be used efficiently. The paper presents a case study of one overflow event lasting 48 h. The calculated theoretical losses of energy (of spilled water) and possible technical implementation for capturing losses are given. The proposed technical implementation is based on established technology, so we could expect that the approach is feasible. The results show that the estimated spilled water energy potential reaches about 40% of the actual spilled water or energy lost.
Keywords: energy loss, spilled water energy, hydropower
Published in DKUM: 13.11.2023; Views: 263; Downloads: 34
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