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Abstract: Erosion of Pelton turbine components due to cavitation and particle-laden flow is a major challenge in hydropower applications, particularly in sediment-rich river environments. This study presents a numerical investigation on how solid particles contribute to the erosion of a Pelton runner. Computational fluid dynamics (CFD) simulations were conducted using ANSYS CFX 2023 R2, incorporating a Lagrangian particle tracking approach and the Finnie abrasion model to predict erosion patterns under varying sediment concentrations. The results indicate that, under normal sediment conditions, particle erosion does not significantly contribute to blade tip damage. However, under extreme sediment loading, the predicted erosion patterns closely match real-world observations, particularly at the blade tip.
Keywords: Pelton turbine, solid particle erosion, cavitation, CFD simulation
Published in DKUM: 09.12.2025; Views: 0; Downloads: 7
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Abstract: Eden izmed produktov obdelave odpadkov je gorivo iz odpadkov (RDF) z visoko kurilno vrednostjo. Kljub visokemu energetskemu potencialu ni pogosto izkoriščen, najpogosteje se ga uporablja za sosežiganje v cementarnah ali toplarnah, lahko se ga predela tudi s pirolizo. V magistrski nalogi je opisana raziskava možne uporabnosti RDF z primešanimi različnimi deleži plastike (HDPE). Rezultati raziskave kažejo, da imajo tako pridobljena pirolizna olja, visok energetski potencial in jih je mogoče uporabiti v več različnih aplikacijah, ne le v procesu sežiganja. S tem bi lahko zmanjšali odvisnost od tujih sežigalnic in omogočili učinkovitejšo, okolju prijaznejšo rabo odpadkov.
Keywords: RDF, piroliza, gorivo iz odpadkov, termična razgradnja
Published in DKUM: 16.09.2025; Views: 0; Downloads: 13
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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: Waste-to-energy (WtE) is a key part of modern waste management. In the European Union, approximately 500 WtE plants process more than 100 million tons of waste yearly, while globally, more than 2700 plants handle over 500 million tons. Roughly 20% of the waste processed is bottom ash (BA). However, this ash can contain heavy metals in concentrations that may render it hazardous. This paper presents a study focusing on stabilizing municipal solid waste incineration BA using simple and industrially viable treatments. The Slovenian WtE plant operator wishes to install the stabilization process; thus, the samples obtained from the plant were treated (1) with a CO2 gas flow, (2) with water spraying, and (3) with a combination of water spraying and a CO2 gas flow under laboratory conditions. Thermodynamic calculations were applied to define potential reactions during the treatment processes in the temperature range from 0 to 100 ◦C and to define the equilibrium composition of the treated ash with additions of CO2 and water. The standard leaching test EN 12457-4 of treated ash shows a reduction of over 40% in barium concentration and over 30% in lead concentration in leachates.
Keywords: heavy metals, waste-to-energy, bottom ash, leachate, reuse
Published in DKUM: 10.03.2025; Views: 0; Downloads: 10
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Abstract: Proučevan je bil vpliv dodatka piroliznega olja, pridobljenega iz polietilena nizke gostote dizelskemu gorivu na pojavnost kavitacije v vbrizgalni šobi dizelskega motorja. V numerični simulaciji s programsko opremo Ansys Fluent so bile upoštevane lastnosti treh različnih goriv: čistega dizelskega goriva, dizelskega goriva z dodatkom 10% in 20% piroliznega olja (volumski deleži). Analiza rezultatov je pokazala, da dodajanje piroliznega olja dizelskemu gorivu vpliva na pojavnost kavitacije. Najnižja pojavnost kavitacije je bila zabeležena pri sto odstotnem dizelskem gorivu, najvišja pa pri gorivu z dodatkom 20% piroliznega olja. Pirolizno olje, pridobljeno iz polietilena nizke gostote ima nižji vrednosti viskoznosti in gostote kot dizelsko gorivo. Možno je sklepati, da nižji vrednosti viskoznosti in gostote vplivata na večjo pojavnost kavitacije pri gorivu z višjim volumskim deležem piroliznega olja iz polietilena nizke gostote v zmesi.
Keywords: kavitacija, računalniška dinamika tekočin, pirolizno olje, polietilen nizke gostote, vbrizgalna šoba, dizelski motor
Published in DKUM: 08.01.2025; Views: 0; Downloads: 41
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