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1.
Numerical analysis of a wind turbine blade with different software
Gorazd Hren, 2019, original scientific article

Abstract: The development of wind power generation technology recognises the wind turbine blade design and manufacturing as crucial for its performance. The laboratory size wind turbine blade was analysed, considering the 3D printing plastic material for blades. Applying the structural dynamic equations of blades, the aero-elastic model of the rotating rotor and the numerical simulation method of the deflections are presented under the aerodynamic loads and centrifugal forces. Based on the parameters of aerofoil and the geometrical parameters of blade, 3D model of the blade was established with the modelling software. Then the model was introduced into computational flow dynamics software to carry out the loads on the blade and further into numerical structural analysis. The analysis was performed in two different software packages. Design of wind turbine blades depends on high precision, reliable and robust numerical predictions of performance where the plug-in software is found to be inadequate for nontrivial problems.
Keywords: computational fluid dynamics, numerical analysis, structural analysis, wind turbine blade
Published in DKUM: 22.02.2024; Views: 157; Downloads: 11
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2.
Experimental and Numerical Research of Micro Wind Turbine for Low Wind Speeds
Matej 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: 191; Downloads: 12
.pdf Full text (18,06 MB)
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3.
Reversible pump-turbines - a study of pumping mode off-design conditions
Uroš Ješe, Aleš Skoták, 2020, original scientific article

Abstract: The role of pumped storage power plants (PSP) in electrical grid systems has been changing in recent years. Demands for switching from pumping to generating mode are becoming increasingly frequent. Moreover, the operating ranges of the reversible pump-turbines used in PSP systems are becoming wider in order to use the PSP as a regulator and a stabilizer of the electrical grid. The primary challenges in the development of pump-turbines are the hydraulic instabilities that occur in pumping and generating modes. The present paper focuses on partial load pumping mode instabilities, such as cavitation and rotating stall. Modern tools, such as CFD, are used for the analysis of the phenomena along with conventional experimental approaches. Rotating stall has been investigated in hydraulic laboratory experimentally and reproduced numerically using commercial CFD code. Three rotating stall cells with a rotational frequency of 2.5% of nominal pump-turbine frequency have been identified. Cavitating vortices related to rotating stall were found in the guide vanes region. Both phenomena indicate highly unstable and potentially dangerous operating conditions that need to be investigated in detail. Understanding the causes for the instabilities will lead to an improved pump-turbine design that will enable safer, more flexible and more reliable operating with fewer unwanted instabilities.
Keywords: pump-turbine, rotating stall, cavitation, Pumping mode instabilities
Published in DKUM: 01.12.2023; Views: 230; Downloads: 3
.pdf Full text (2,46 MB)
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4.
Off-design flow analysis of cogeneration steam turbine with real process data
Dušan Strušnik, Igor Kuštrin, Jurij Avsec, 2022, original scientific article

Abstract: This paper presents the concept of reconstruction of the existing coal-fired combined heat and power plant to comply with new European environmental policies. The existing coal-fired boiler will be replaced by two new dual pressure heat recovery steam generators, which will utilize the exhaust gas heat from two new gas turbines. The steam from the heat recovery steam generators will be fed to the existing steam turbine. After the reconstruction, the nominal turbine inlet steam mass-flow of 40 kg/s will be reduced to 30 kg/s. During periods of low heat demand, only one gas turbine and one heat recovery steam generator will be in operation and the live steam mass-flow may drop even to 12 kg/s. Prior to the reconstruction, dedicated tests of the existing steam turbine were carried out using the steam from the existing coal-fired boiler. The goal of the test was to verify the viability of operation with such an extremely low mass-flow. The results of tests show that such operation is possible but inefficient from a power generation point of view. Besides this, the turbine control algorithm needs to be accommodated to this extreme operating regime and additional measures like displacement of the extraction points and steam cooling will be required to control the temperature of the steam extractions. The novelty of this paper is using real prereconstruction process data for the assessment of feasibility and efficiency of the post-reconstruction operation of a combined heat and power turbine.
Keywords: cogeneration, control valves, exhaust gas, heat recovery, steam turbine
Published in DKUM: 30.10.2023; Views: 132; Downloads: 11
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5.
Obratovalne karakteristike modela vetrne turbine v cevi in v prostem toku : diplomsko delo
Klementina Cifer, 2022, undergraduate thesis

Abstract: Diplomska naloga »Obratovalne karakteristike modela vetrne turbine v cevi in v prostem toku« je zasnovana na ideji, da meritve karakteristik modelov vetrnih turbin v cevi ne dajejo verodostojnih rezultatov, ker hitrostni in tlačni profil v cevi vplivata na karakteristiko. Meritve so opravljene pod kontroliranimi pogoji v laboratoriju. Z ventilatorjem se je ustvaril veter, ki se mu je z meritvami določila hitrost ter izračunala moč. Električna moč se je določila prek meritev toka in napetosti ter vrtljajev turbine. Mehanska moč se je določila z napetostmi na merilnih trakovih ter z izkustvenimi enačbami. Rezultati so pokazali, da se modeli v prostem toku obnašajo zelo drugače kot v cevi.
Keywords: vetrne turbine, obratovalne karakteristike, izkoristki, energija vetra, meritve v cevi in v prostem toku, obnovljivi viri energije
Published in DKUM: 29.09.2022; Views: 348; Downloads: 56
.pdf Full text (2,43 MB)

6.
Primerjava karakteristik alternativnih vodnih turbin za malo HE
Simon Trupi, 2019, undergraduate thesis

Abstract: Namen diplomskega dela je primerjava karakteristik alternativnih vodnih turbin s karakteristikami klasičnih vodnih turbin za malo hidroelektrarno. Male vodne hidroelektrarne so specifične, predvsem v padcu in pretoku vode, ki jo lahko izkoristimo za proizvodnjo električne energije. V diplomskem delu na konkretnem primeru ugotavljamo učinkovitost in rentabilnost alternativnih vodnih turbin, in ugotavljamo katera je v danem primeru najprimernejša. Ugotovili smo, da je izbrana alternativna turbina ugodna zamenjava za klasično vodno turbino.
Keywords: alternativne vodne turbine, mala hidroelektrarna, obnovljivi viri energije
Published in DKUM: 18.07.2019; Views: 1990; Downloads: 141
.pdf Full text (4,59 MB)

7.
Napoved energetske in ekonomske učinkovitosti vetrne turbine s programskim paketom RETScreen Expert : diplomsko delo
Patrik Ambrožič, 2018, undergraduate thesis

Abstract: Diplomska naloga obravnava energetsko in ekonomsko analizo vetrne elektrarne s programskim paketom RETScreen Expert. Analiza je sestavljena iz šestih korakov, ki jih omogoča program. Lokacija postavitve vetrne elektrarne je Lisca, ki je vrh nad Sevnico. Vetrno polje je sestavljeno iz petih turbin nemškega proizvajalca Enercon E53. Podatki so izbrani iz baze podatkov samega programa, hitrost vetra je vnesena po podatkih Agencije Republike Slovenije za okolje, odkupna cena električne energije iz vetrnih elektrarn pa je izbrana iz portala Energetika Ministrstva za Infrastrukturo. Na podlagi opravljene analize smo ugotovili, da bi se izgradnja vetrne elektrarne ne bi izplačala.
Keywords: vetrne elektrarne, vetrne turbine, vetrna energija, energetska učinkovitost, ekonomičnost, analiza učinkovitosti, programska podpora, Lisca, RETScreen Expert
Published in DKUM: 12.10.2018; Views: 1552; Downloads: 130
.pdf Full text (1,83 MB)

8.
Design of geometry and numerical simulation of the operating characteristic of the rotor of the wind turbine : diplomsko delo
aljaž Janič, 2018, undergraduate thesis

Abstract: The diploma thesis consists of design and numerical simulation of the wind turbine. Geometries are designed according to two theories, the Betz theory and the Schmitz theory. I used Solidworks for 3D modeling of the both rotors. Using Ansys software package, we performed numerical simulations of a rigid body for two different wind speed regimes. We were interested in the angular velocity of the spinning blades, which in combination with moment give us power.
Keywords: Renewable energy, wind energy, numerical simulation, wind turbine, blade design, Betz and Schmitz theory
Published in DKUM: 09.08.2018; Views: 1517; Downloads: 186
.pdf Full text (2,19 MB)

9.
On-line condition monitoring and evaluation of remaining useful lifetimes for mineral hydraulic and turbine oils
Vito Tič, Darko Lovrec, 2017, scientific monograph

Abstract: Condition monitoring of hydraulic and turbine oils, and especially their remaining useful life, is becoming an important strategic business advantage for plant owners, which benefits in environment protection and cost reduction. This monograph discusses the problem of condition monitoring of hydraulic fluids throughout their life-cycles. Particular emphasis is placed on assessing mineral-based oils’ conditions and their remaining useful lifetimes quantitatively. Practicality and usefulness are vital when developing and deploying various methods for condition monitoring systems within industrial environments. Therefore, it is important to know the oil degradation mechanisms and influencing factors, commonly used laboratory methods and oil ageing tests, as well as, for on-line condition monitoring system design, the available sensors with all their characteristics and restrictions. The proposed approach is based on a novel method for testing the durability and oxidation stability of different hydraulic and turbine oils. The developed mathematical model is based on data from previously conducted oil-ageing tests for the assessment of an oil's condition and its remaining useful lifetime. The method can also be used for comparison of different oils and selection of a more adequate oil with high oxidation stability and long service-lifetime.
Keywords: Hydraulic and turbine oils, degradation mechanisms, on-line condition monitoring, test methods, remaining useful lifetime
Published in DKUM: 22.12.2017; Views: 1581; Downloads: 406
.pdf Full text (7,75 MB)
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10.
Preračun geometrije lopatice vetrne turbine in prenos v cad sistem
Igor Ščuri, 2017, master's thesis

Abstract: Za magistersko nalogo smo izvedli proceduro za izračun geometrije lopatice vetrne turbine v Excelu. Izračun geometrije lopatice temelji na metodi »Blade element theory«, ki je del BEM metode. Razika med našo proceduro in omenejima metodama je le v tem, da je v omenjenih metodah geometrija lopatice vetrne turbine že dana. Preračunano geometrijo s pomočjo izvedenega programa prenesemo v program SolidWorks tako, da program najprej izriše krivulje profilov in jih podem s funkcijo »Loft« poveže v lopatico. Program izračuna optimalno geometrijo lopatice z upoštevanjem rotirajoče brazde, ki je modelirana v SolidWorksu. Geometrijo lopatice preračunamo le s kliki na gumbe v programu, prav tako jo s kliki na gumbe tudi modeliramo v SolidWorksu. V nalogi je natančneje predstavljeno delovanje programa.
Keywords: preračun, geometrija lopatice vetrne turbine, modeliranje
Published in DKUM: 18.08.2017; Views: 1646; Downloads: 120
.pdf Full text (2,90 MB)

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