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  • 1.
    Amanatidou, Rebeka
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    CFD Measurements of the Cooling Air in a DC-Motor2008Självständigt arbete på grundnivå (kandidatexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

     

    The cooling system of a DC-motor is examined in this thesis. A change of direction of the cooling air is desired to prevent the generated coal dust from entering into the windings of the machine. Ultimately this will have a negative effect on the cooling in the machine and the loss of cooling needs to be compensated through other ways. The purpose of this thesis is to work for an improved operational safety and performance of the DC-motor and to make it more competitive in the market. By modelling the interior geometry of the machine and defining the boundaries in the software programs Gambit and FLUENT respectively, the motion and the heat transfer of the airflow could be simulated. The simulation results would give us an understanding of the flow pattern which later could be used to develop design modifications on the cooling system of a DC-motor. In this thesis the main focus lies on creating a simulation model with a sufficiently fine mesh size.

  • 2.
    Aslanidou, Ioanna
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. University of Oxford, United Kingdom.
    Rosic, Budimir
    University of Oxford, United Kingdom.
    Aerothermal Performance of Shielded Vane Design2017Ingår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 139, nr 11, artikel-id 111003Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents an experimental investigation of the concept of using the combustor transition duct wall to shield the nozzle guide vane leading edge. The new vane is tested in a high-speed experimental facility, demonstrating the improved aerodynamic and thermal performance of the shielded vane. The new design is shown to have a lower average total pressure loss than the original vane, and the heat transfer on the vane surface is overall reduced. The peak heat transfer on the vane leading edge–endwall junction is moved further upstream, to a region that can be effectively cooled as shown in previously published numerical studies. Experimental results under engine-representative inlet conditions showed that the better performance of the shielded vane is maintained under a variety of inlet conditions.

  • 3.
    Aslanidou, Ioanna
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Rosic, Budimir
    University of Oxford, United Kingdom.
    Effect of the Combustor Wall on the Aerothermal Field of a Nozzle Guide Vane2018Ingår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 140, nr 5, artikel-id 051010Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In gas turbines with can combustors the trailing edge of the combustor transition duct wall is found upstream of ev- ery second vane. This paper presents an experimental and numerical investigation of the effect of the combustor wall trailing edge on the aerothermal performance of the nozzle guide vane. In the measurements carried out in a high speed experimental facility, the wake of this wall is shown to in- crease the aerodynamic loss of the vane. On the other hand, the wall alters secondary flow structures and has a protective effect on the heat transfer in the leading edge-endwall junc- tion, a critical region for component life. The different clock- ing positions of the vane relative to the combustor wall are tested experimentally and are shown to alter the aerothermal field. The experimental methods and processing techniques adopted in this work are used to highlight the differences be- tween the different cases studied. 

  • 4.
    Aslanidou, Ioanna
    et al.
    University of Oxford, United Kingdom.
    Rosic, Budimir
    University of Oxford, United Kingdom.
    Kanjirakkad, Vasudevan
    University of Sussex, United Kingdom.
    Uchida, Sumiu
    Mitsubishi Heavy Industries, Japan.
    Leading Edge Shielding Concept in Gas Turbines With Can Combustors2012Ingår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 135, nr 2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The remarkable developments in gas turbine materials and cooling technologies haveallowed a steady increase in combustor outlet temperature and, hence, in gas turbine efficiencyover the last half century. However, the efficiency benefits of higher gas temperature,even at the current levels, are significantly offset by the increased losses associatedwith the required cooling. Additionally, the advancements in gas turbine cooling technologyhave introduced considerable complexities into turbine design and manufacture.Therefore, a reduction in coolant requirements for the current gas temperature levels isone possible way for gas turbine designers to achieve even higher efficiency levels. Theleading edges of the first turbine vane row are exposed to high heat loads. The high coolantrequirements and geometry constraints limit the possible arrangement of the multiplerows of film cooling holes in the so-called showerhead region. In the past, investigatorshave tested many different showerhead configurations by varying the number of rows, inclinationangle, and shape of the cooling holes. However, the current leading edge coolingstrategies using showerheads have not been shown to allow a further increase inturbine temperature without the excessive use of coolant air. Therefore, new coolingstrategies for the first vane have to be explored. In gas turbines with multiple combustorchambers around the annulus, the transition duct walls can be used to shield, i.e., to protect,the first vane leading edges from the high heat loads. In this way, the stagnationregion at the leading edge and the showerhead of film cooling holes can be completelyremoved, resulting in a significant reduction in the total amount of cooling air that is otherwiserequired. By eliminating the showerhead the shielding concept significantly simplifiesthe design and lowers the manufacturing costs. This paper numerically analyzes the potentialof the leading edge shielding concept for cooling air reduction. The vane shape wasmodified to allow for the implementation of the concept and nonrestrictive relative movementbetween the combustor and the vane. It has been demonstrated that the coolant flowthat was originally used for cooling the combustor wall trailing edge and a fraction of thecoolant air used for the vane showerhead cooling can be used to effectively cool both thesuction and the pressure surfaces of the vane.

  • 5.
    Aslanidou, Ioanna
    et al.
    University of Oxford, United Kingdom.
    Rosic, Budimir
    University of Oxford, United Kingdom.
    Kanjirakkad, Vasudevan
    University of Sussex, United Kingdom.
    Uchida, Sumiu
    Mitsubishi Heavy Industries, Japan.
    Leading edge shielding concept in gas turbines with can combustors2012Konferensbidrag (Refereegranskat)
  • 6.
    Aslanidou, Ioanna
    et al.
    Cranfield University, United Kingdom.
    Zachos, Pavlos K.
    Cranfield University, United Kingdom.
    Pachidis, Vassilios
    Cranfield University, United Kingdom.
    Singh, Riti
    Cranfield University, United Kingdom.
    Sub-idle & Relight Performance Modelling; A fully parametrical method for sub-idle compressor maps generation2009Konferensbidrag (Övrigt vetenskapligt)
  • 7.
    Bergman, David
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Modelling & implementation of Aerodynamic Zero-lift Drag into ADAPDT2009Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Målet med detta examensarbete var att skapa och implementera en algoritm som införmöjligheten att beräkna nollmotstånd för givna flygplansgeometrier i programmet ADAPDT.ADAPDT, kort för AeroDynamic Analysis and Preliminary Design Tool, är ett program som,baserat på potential strömnings teori, beräknar krafter och moment på en geometri uppbyggd avplana plattor. Nollmotståndet kommer att baseras en kombination av handboksmetoder somfunnits lämpliga och applicerbara på geometridefinitionen given i ADAPDT.

    Motstånd har sitt ursprung i två fysikaliska fenomen: friktion och tryckfördelning, ur vilka alltmotstånd som agerar på ett flygplan härrör. Inom flyget delar man in motståndet ilyftkraftsberoende inducerat motstånd samt geometriberoende nollmotstånd.

    Hur pålitliga och noggranna motståndsberäkningarna kan förväntas vara beror på mängdengeometriska data som finns att tillgå. ADAPDT:s geometridefinition är begränsad till planaplattor men trots detta finns potential att leverera stora mängder data och resultat med rimlignoggrannhet. Plan plattgeometrin visade sig, för kroppsgeometrin, väldigt begränsad ochotillräcklig medan ving element kunde beskrivas med större noggrannhet.

    En rad olika empiriska handboksmetoder användes för att skapa nollmotståndsalgoritmen. Vidvalet av formler och ekvationer var det viktigt att välja sådana som ADAPDT kunde försetillräckligt med data till. Samtidigt fick formlerna inte vara alltför simpla så att måttet avnoggrannhet i resultaten vart alltför låg mot för vad som, för ändamålet, är förväntat.

    Slutligen valdes fyra kända flygplan, med nollmotståndsdata tillgängligt, att modeleras medADAPDT:s plan plattgeometri för att validera, verifiera och utvärdera algoritmens mått avtillförlitlighet. Resultaten för mer konventionella flygplanskonfigurationer visade på ett relativtfel mellan 0-15 % mot de givna referensflygplanens nollmotståndsdata inom hastigheterna 0 tillMach 1,2. För mer komplicerade konfigurationer steg det relativa felet omedelbart upp mot 40% inom samma hastighetsregim. Men även om den begränsade geometridefinitionen iADAPDT är grunden för mycket osäkerheter förser den slutliga produkten ändå programmetmed en väldigt god möjlighet till skattning av nollmotståndet som inte tidigare fanns. Enmöjlighet som över tid, allteftersom ADAPDT forstätter att utvecklas, har all potential till attförbättras med avseende på noggrannhet och tillförlitlighet.

  • 8.
    Gustafsson, Linda
    Mälardalens högskola, Institutionen för samhällsteknik.
    Undersökning av ljudnivåer på skolgårdar: - samt hur fasad och fönster dimensioneras med uppmätta värden2009Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [en]

    This report is written on commission by WSP Acoustics. The report studies the outdoor sound levels on school yards in Stockholm. The questions given by the company to be answered was what are the actual sound levels at diffrent school yards with low traffic noise and how can you construct a facade element that reduces the sound level from the outside and meet the indoor requirements. Mesurements for four hours was done at eight schools set north and south of the city centre. The measurement period included one school break and one lunch break. The results of the measurements were that the equivalent and maximum sound level had small variations between the schools with some exceptions.The equivalent sound level was Leq 58-62 dB(A) and this shows a small variation. The school with the highest equivalent sound level of 67 dB was Maria skolan. This high level can be explained by more children on the school yard together at the same time etc. The maximum sound level was 85-89 dB(A), this if the level for Sofia skolan 82 dB was ignored. The level 85-89 dB(A) also shows a small variation. Calculations of the sound reduction index (R'w) for facade elements were also carried out for all the schools. The resulting sound reduction index for the whole facade was 34-41 dB. After assuming a 200 mm thick concrete facade for Sjöstadsskolan another calculation of building elements gives that the window have to reduce R'w 32 dB to meet the indoor requirements. In the future WSP Acoustics will use this report to choose building elements such as windows when building or rebuilding schools. It can also be used if any of the eight schools in this report needs a window changed to improve the acoustics.

  • 9.
    Hardie, Staffan
    Mälardalens högskola, Institutionen för matematik och fysik.
    Drag Estimations on Experimental Aircraft Using CFD2007Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [sv]

    Det approximerade värdet på luftmotståndet som gjordes I den preliminära designfasen behövde verifieras. En flygplansmodell har analyserats med CFD och resultaten har undersökts för att se hur exakta antagandena var. En analys gjordes steg för steg och slutligen har en simulering utförts. Det uppmätta luftmotståndet motsvarade inte målet i den preliminära designfasen. Flera olika anledningar till detta diskuteras. Analysen visar att denna flygplansdesign fungerar bra aerodynamiskt men identifierar också en del punkter på vilken den kan förbättras.

  • 10.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Västerås, Sweden.
    Bel Fdhila, Rebei
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Västerås, Sweden.
    Daneryd, Anders
    ABB AB, Corporate Research, Västerås, Sweden.
    Heat transfer by liquid jets impinging on a hot flat surface2016Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 164, nr 15, s. 934-943Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Runout Table (ROT) cooling is one of the most important factors for controlling quality of hot rolled steel. ROT cooling uses large quantities of water to cool the steel plate. Optimizing heat transfer in the ROT would reduce the amount of water used, which will lower the amount of energy needed for pumping, filtering, storage and use of water. Optimization will therefore result in a direct energy saving as well as increasing the product quality.

    This study investigates heat transfer by turbulent water jets impinging on a hot flat steel plate at temperatures below the boiling point in order to understand convection heat transfer phenomena. This is an important stage that precedes the boiling and addresses the applicability of the heat transfer correlations available in the literature.

    A single axisymmetric jet and a pair of interacting jets are simulated using Computational Fluid Dynamics (CFD). The Reynolds Averaged Navier Stokes (RANS) model under steady and transient conditions and the kɛ turbulence model are used in both 2D axisymmetric and 3D simulations. We investigate the influence of the water flow rate on the jet cooling characteristics and develop a correlation for the radial position of the maximum Nusselt number based on numerical results.

    Two sets of boundary conditions – constant temperature and constant heat flux – are applied at the surface of the steel plate and evaluated. The single jet numerical results compare favourably with published data based on measurements and analytical models. The thermal performance of a two-jet system was found to be no better than a single jet because the jets were too far from each other to generate any additional thermal interaction.

  • 11.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Bel Fdhila, Rebei
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Daneryd, Anders
    ABB, Sweden.
    Multi-Jet Impingement Cooling of a Hot Flat Steel Plate2014Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 61, s. 1835-1839Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One of the most important steps to control the quality in steel hot rolling is the Runout Table (ROT) Cooling. In this investigation, the heat transfer of water jets impinging on a hot flat steel plate was studied under temperatures below the boiling point to understand the convection heat transfer phenomena which is a major step preceding the boiling. Single axisymmetric jet and a pair of interacting jets are simulated using Computational Fluid Dynamics (CFD). The RANS model under steady and transient conditions as well as the k-Ɛ turbulence model are used for both 2D axisymmetric and 3D simulations. The water flow rate influence on the jets cooling characteristics is investigated.Two sets of boundary conditions, constant temperature and constant heat flux were applied at the surface of the steel plate and evaluated. The single jet numerical results are successfully compared to published data based on measurements and analytical models. The two jets thermal performance was found to be unaffected because the jets are too far from each other to generate any additional thermal interaction.

  • 12.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Bel Fdhila, Rebei
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Simulation and validation of flow and heat transfer in an infinite mini-channel using Smoothed Particle Hydrodynamics2018Ingår i: Energy Procedia, Elsevier, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fluid flow and heat transfer in small channels have a wide range of engineering and medical applications. It has always been a topic of numerous theoretical, numerical and experimental studies. Several numerical methods have been used to simulate such flows. The most common approaches are the finite volume method (FVM) and the direct numerical simulation (DNS), which are numerically expensive to solve cases involving complex engineering problems. The main purpose of this work is to investigate the usability of the mesh-free particle based Smoothed Particle Hydrodynamics (SPH) method to simulate convective heat transfer. To validate our approach, as a starting point, we choose to solve a simple well-established problem which is the laminar flow and heat transfer through an infinitely long mini-channel. The solution obtained from SPH method has been compared to the solution from FVM method and analytical solution with good accuracy. The results presented in this paper show that SPH is capable to solve laminar forced convection heat transfer, however, turbulent flow cases need to be considered to be able to utilize the SPH method for engineering thermal applications.

  • 13.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Domínguez, José
    University of VIGO, Spain.
    Crespo, Alejandro
    University of VIGO, Spain.
    Bel Fdhila, Rebei
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Smoothed Particle Hydrodynamics modeling of transient conduction and convection heat transferManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Smoothed Particle Hydrodynamics (SPH) is a mesh-free particle method that has been widely used in the last years to model some complex flows. SPH was mainly used to investigate problems related to hydrodynamics and maritime engineering where heat transfer is of no importance. Thermal problems have seldom been addressed due to the limitation of the main commercial and open-source SPH codes.

    In this article, the energy equation is implemented in the SPH based open-source code DualSPHysics to solve conduction and forced convection heat transfer problems. Laminar flow cases are simulated as the first validation cases of the implemented model. The studied cases include conduction in an aluminum block, conduction in still water in a cavity, laminar water flow between two infinite parallel plates and tube bank heat exchanger. The thermal solutions obtained from SPH are benchmarked with the solutions from Finite Volume Method (FVM) and also validated using available analytical solutions. The obtained results are in good agreement with FVM and available analytical models, which combined with the advantages of the meshless approach, show the high potential for industrial heat transfer applications.

    This development is an important step towards thermal optimization of several industrial applications that can’t benefit from the conventional FVM approach due to geometry or process complexities. The demonstrated SPH simulation and visualization capabilities contribute to build the future reliable energy-saving solutions.

  • 14.
    Hosain, Md Lokman
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Västerås, Sweden.
    Fdhila, Rebei Bel
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB AB, Corporate Research, Västerås, Sweden.
    Rönnberg, Kristian
    ABB AB, Corporate Research.
    Air-Gap Flow and Thermal Analysis of Rotating Machines using CFD2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, s. 5153-5159Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal management of the rotating electrical machines is a very challenging area which needs appropriate solutions for each machine and operating condition. The heat is generated by the electromagnetic losses and the mechanical friction during the rotation. Computational Fluid Dynamics (CFD) is used in this study to predict and analyze the thermal performance of a rotating electrical machine where high speed rotation is coupled with small flow gaps. The investigation presented in this paper is based on a geometry used for model assessment and verification purposes. However, the approach outlined and the observations made are transferrable to other geometries. ANSYS Fluent has been used to perform CFD simulation where both the air velocity field and the temperature distribution are obtained. The results are qualitatively highly interesting to understand the thermal behavior within an electrical machine operations. The results show a periodic temperature distribution on the stator surface with similar periodic pattern for the heat transfer coefficient on the rotor surface. The simulated average heat transfer coefficient at the rotor surface is compared with the correlations from published literature with an overall good agreement.

  • 15.
    Kyprianidis, Konstantinos G.
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University.
    Sethi, Vishal
    Cranfield University.
    Ogaji, Stephen O. T.
    Cranfield University.
    Pilidis, Pericles
    Cranfield University.
    Singh, Riti
    Cranfield University.
    Kalfas, Anestis I.
    Aristotle University of Thessaloniki.
    Thermo-Fluid Modelling for Gas Turbines-Part I: Theoretical Foundation and Uncertainty Analysis2009Ingår i: ASME TURBO EXPO 2009 Proceedings, GT2009-60092, 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this two-part publication, various aspects of thermo-fluidmodelling for gas turbines are described and their impact onperformance calculations and emissions predictions at aircraftsystem level is assessed. Accurate and reliable fluid modellingis essential for any gas turbine performance simulation softwareas it provides a robust foundation for building advanced multidisciplinarymodelling capabilities. Caloric properties forgeneric and semi-generic gas turbine performance simulationcodes can be calculated at various levels of fidelity; selection ofthe fidelity level is dependent upon the objectives of thesimulation and execution time constraints. However, rigorousfluid modelling may not necessarily improve performancesimulation accuracy unless all modelling assumptions andsources of uncertainty are aligned to the same level. Certainmodelling aspects such as the introduction of chemical kinetics,and dissociation effects, may reduce computational speed andthis is of significant importance for radical space explorationand novel propulsion cycle assessment.

    This paper describes and compares fluid models, based ondifferent levels of fidelity, which have been developed for anindustry standard gas turbine performance simulation code and an environmental assessment tool for novel propulsion cycles.The latter comprises the following modules: engineperformance, aircraft performance, emissions prediction, andenvironmental impact. The work presented aims to fill thecurrent literature gap by: (i) investigating the commonassumptions made in thermo-fluid modelling for gas turbinesand their effect on caloric properties and (ii) assessing theimpact of uncertainties on performance calculations andemissions predictions at aircraft system level.

    In Part I of this two-part publication, a comprehensiveanalysis of thermo-fluid modelling for gas turbines is presentedand the fluid models developed are discussed in detail.Common technical models, used for calculating caloricproperties, are compared while typical assumptions made influid modelling, and the uncertainties induced, are examined.Several analyses, which demonstrate the effects of composition,temperature and pressure on caloric properties of workingmediums for gas turbines, are presented. The working mediumsexamined include dry air and combustion products for variousfuels and H/C ratios. The errors induced by ignoringdissociation effects are also discussed.

  • 16.
    Kyprianidis, Konstantinos G.
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University.
    Sethi, Vishal
    Cranfield University.
    Ogaji, Stephen O. T.
    Cranfield University.
    Pilidis, Pericles
    Cranfield University.
    Singh, Riti
    Cranfield University.
    Kalfas, Anestis I.
    Aristotle University of Thessaloniki.
    Thermo-Fluid Modelling for Gas Turbines-Part II: Impact on Performance Calculations and Emissions Predictions at Aircraft System Level2009Ingår i: ASME TURBO EXPO 2009 Proceedings, GT-2009-60101, 2009, s. 483-494Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this two-part publication, various aspects of thermo-fluidmodelling for gas turbines are described and their impact onperformance calculations and emissions predictions at aircraftsystem level is assessed. Accurate and reliable fluid modellingis essential for any gas turbine performance simulation softwareas it provides a robust foundation for building advanced multidisciplinarymodelling capabilities. Caloric properties forgeneric and semi-generic gas turbine performance simulationcodes can be calculated at various levels of fidelity; selection ofthe fidelity level is dependent upon the objectives of thesimulation and execution time constraints. However, rigorousfluid modelling may not necessarily improve performancesimulation accuracy unless all modelling assumptions andsources of uncertainty are aligned to the same level. Certainmodelling aspects such as the introduction of chemical kinetics,and dissociation effects, may reduce computational speed andthis is of significant importance for radical space explorationand novel propulsion cycle assessment.

    This paper describes and compares fluid models, based ondifferent levels of fidelity, which have been developed for anindustry standard gas turbine performance simulation code and an environmental assessment tool for novel propulsion cycles.The latter comprises the following modules: engineperformance, aircraft performance, emissions prediction, andenvironmental impact. The work presented aims to fill thecurrent literature gap by: (i) investigating the commonassumptions made in thermo-fluid modelling for gas turbinesand their effect on caloric properties and (ii) assessing theimpact of uncertainties on performance calculations andemissions predictions at aircraft system level.

    In Part II of this two-part publication, the uncertaintyinduced in performance calculations by common technicalmodels, used for calculating caloric properties, is discussed atengine level. The errors induced by ignoring dissociation areexamined at 3 different levels: i) component level, ii) enginelevel, and iii) aircraft system level. Essentially, an attempt ismade to shed light on the trade-off between improving theaccuracy of a fluid model and the accuracy of a multidisciplinarysimulation at aircraft system level, againstcomputational time penalties. The results obtained demonstratethat accurate modelling of the working fluid is not alwaysessential; the accuracy/uncertainty for an overall engine modelwill always be better than the mean accuracy/uncertainty of the individual component estimates as long as systematic errors arecarefully examined and reduced to acceptable levels to ensureerror propagation does not cause significant discrepancies.Computational time penalties induced by improving theaccuracy of the fluid model as well as the validity of the idealgas assumption for future turbofan engines and novelpropulsion cycles are discussed.

  • 17.
    Li, H.
    et al.
    Royal Institute of Technology, Sweden.
    Ji, X.
    Royal Institute of Technology, Sweden.
    Yan, Jinyue
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling. Royal Institute of Technology, Sweden.
    A new modification on RK EOS for gaseous CO2 and gaseous mixtures of CO2 and H2O2006Ingår i: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 30, nr 3, s. 135-148Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To develop an equation of state with simple structure and reasonable accuracy for engineering application, Redlich-Kwong equation of state was modified for gaseous CO2 and CO2-H2O mixtures. In the new modification, parameter a of gaseous CO2 was regressed as a function of temperature and pressure from recent reliable experimental data in the range: 220-750 K and 0.1-400 MPa. Moreover, a new mixing rule was proposed for gaseous CO2-H2O mixtures. To verify the accuracy of the new modification, densities were calculated and compared with experimental data. The average error is 1.68% for gaseous CO2 and 0.93% for gaseous mixtures of CO2 and H2O. Other thermodynamic properties, such as enthalpy and heat capacities of CO2 and excess enthalpy of gaseous CO2-H2O mixtures, were also calculated; results fit experimental data well, except for the critical region.

  • 18.
    Luque, Salvador
    et al.
    University of Oxford, United Kingdom.
    Kanjirakkad, Vasudevan
    University of Sussex, United Kingdom.
    Aslanidou, Ioanna
    University of Oxford, United Kingdom.
    Lubbock, Roderick
    University of Oxford, United Kingdom.
    Rosic, Budimir
    University of Oxford, United Kingdom.
    Uchida, Sumiu
    Mitsubishi Heavy Industries, Japan.
    A New Experimental Facility to Investigate Combustor-Turbine Interactions in Gas Turbines With Multiple Can Combustors2015Ingår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 137, nr 5Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes a new modular experimental facility that was purpose-built to investigateflow interactions between the combustor and first stage nozzle guide vanes (NGVs)of heavy duty power generation gas turbines with multiple can combustors. The first stageturbine NGV is subjected to the highest thermal loads of all turbine components andtherefore consumes a proportionally large amount of cooling air that contributes detrimentallyto the stage and cycle efficiency. It has become necessary to devise novel coolingconcepts that can substantially reduce the coolant air requirement but still allow theturbine to maintain its aerothermal performance. The present work aims to aid this objectiveby the design and commissioning of a high-speed linear cascade, which consists oftwo can combustor transition ducts and four first stage NGVs. This is a modular nonreactiveair test platform with engine realistic geometries (gas path and near gas path), coolingsystem, and boundary conditions (inlet swirl, turbulence level, and boundary layer).The paper presents the various design aspects of the high pressure (HP) blow down typefacility, and the initial results from a wide range of aerodynamic and heat transfermeasurements under highly engine realistic conditions.

  • 19.
    Luque, Salvador
    et al.
    University of Oxford, United Kingdom.
    Kanjirakkad, Vasudevan
    University of Sussex, United Kingdom.
    Aslanidou, Ioanna
    University of Oxford, United Kingdom.
    Lubbock, Roderick
    University of Oxford, United Kingdom.
    Rosic, Budimir
    University of Oxford, United Kingdom.
    Uchida, Sumiu
    Mitsubishi Heavy Industries, Japan.
    A New Experimental Facility to Investigate Combustor-Turbine Interactions in Gas Turbines With Multiple Can Combustors2014Konferensbidrag (Refereegranskat)
  • 20.
    Nabati, Hamid
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Investigation on Numerical Modeling of Water Vapour Condensation from aFlue Gas with High CO2 Content2011Ingår i: Energy and Power Engineering journal, ISSN 1949-243X, Vol. 03, nr 02, s. 181-189Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, the numerical modeling of condensation processof water vapor from a flue gas with high CO2 concentration is studied. Tosimplify the study and focus on the physical model, a simple vertical platewas chosen. Two condensation models are developed. A numericalapproach is considered to implement these models. The main objective inthe current paper was to study the capability of numerical model inprediction of complex process. Results showed that developedcondensation models in combination with numerical approach can predictthe trends in condensation behavior of binary mixture very well. Resultsfrom this study can be developed further to be used in designing ofcondenser which are suitable for oxy-fuel power plants.

  • 21.
    Porian, Bijan
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Modelling of the Chemical Reactions in a Continuous Pulping Digester in the Presence of the Channelling Phenomenon2009Ingår i: International Review of Chemical Engineering Rapid Communications, ISSN 2035-1755, Vol. 1, nr 5, s. 419-427Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pulping digester including the channelling phenomenon and chemical reactions in the channel is modelled using the CFD, finite volume method, FLUENT. The objective of this paper is to predict the chemical and hydraulic behaviour of the digester under the hazardous situations.

    A 2D geometry of the digester is built and symmetric planes are defined in the Gambit. The mesh is then exported to the FLUENT and then the created half geometry was treated by axisymmetric function to establish a complete model of the digester. The Eulerian scheme is applied which    represent the multiphase flows in the digester. A heterogeneous porous media is defined for the compressible bed. Species transport is applied to define a mixture template of the wood chips components. The kappa number is predicted in the channel and around it to characterize the cooking development under hazardous conditions.               

  • 22.
    Pourian, Bijan
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    CFD modelling of solid-liquid multiphase and mathematical separation of the phases in a continuous pulp digester2010Ingår i: International Journal of Modelling and Simulation, ISSN 0228-6203, Vol. 30, nr 3, s. 384-395Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes the use of a CFD multiphase model using commercial FLUENT software to aid understanding of the physical behavior of solid and liquid flows in the digester of the pulping process. We take into consideration the mass balance of the multi-inlets, outlets and circulation flows in the digester. We also look at the application of a Porous media model to describe the dynamic behavior of the liquor flow through a bed of solid particles.

    The cylindrical Korsnas/vallvik pulping digester in Sweden is represented in the models as an axisymmetric two-dimensional model, which includes multiple feeds, outlets, pressure adjustment valves and circulation pipes.

    Separation of the phases is an important part of the pulping process. A number of multiphase models are evaluated for their potential use in phase separation.

    For this evaluation we constructed the two-dimensional digester model in the Gambit software package, a pre- processor tool for FLUENT 

    Physical strainers at the entrances of outlet pipes were designed in Gambit, in order to investigate the possibility of physically separating large solid particles from the liquid flow where both phases are subject to suction into the circulation pipes.

    The compaction of the wood chips is also considered in the modeling. In the Porous model, the digester is divided into sections of different porosity, and the behavior of individual suspension particles  is not considered. The bulk of this paper concerns modeling mass balances and phases of the mixture in the digester using Eulerian and Mixture strategies.

  • 23.
    Pourian, Jan
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Modelling of the channelling phenomenon of the pulping digester using porous Media2009Ingår i: SIMS, Scandinavian Modelling and Simulation  Society 50, conference in Fredrice, Denmark, October 7-8 (2009) / [ed] Brian Elmegard, Fredrice: SIMS electronic , 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    A dynamic model is developed for a continuous pulping digester to characterize the channeling phenomenon. The commercial CFD codes, FLUENT, are used to compute the hydraulic behavior of the digester under the normal and particular operational conditions. All the circulation flows, extractions, multiple inlets and outlets are included in this model. The digester is designed in the Gambit and an axisymmetric 2d model is applied. A porous scheme is implemented in the model in order to design the fluid flow and channelling phenomenon inside the digester. A heterogeneous porous media is specified in order to take the compression of the pulp into account. The simulation can serves as a prognosis model to predict the risk situations and probably to hinder high economical damage. The k- model contributes to compute the flow “regimes” or eventual eddies in some turbulent zones of the digester.

1 - 23 av 23
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