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  • 1.
    Altimira, Mireia
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Analysis of Atomization Systems through Mathematical Modeling and Experimentation: Application to Industrial Fan-Spray Atomizers2010Doctoral thesis, monograph (Other academic)
  • 2.
    Altimira, Mireia
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    OPTIMIZACIÓN DEL DISEÑO DE SISTEMAS DE ATOMIZACIÓN DE LÁMINA LÍQUIDA MEDIANTE MODELACIÓN MATEMÁTICA Y EXPERIMENTACIÓN2008Licentiate thesis, monograph (Other academic)
  • 3.
    Altimira, Mireia
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    RAISING AWARENESS ON DIVERSITY AND EQUALITY IN STEM DEGREES IN HIGHER EDUCATION2017In: INTED2017: 11TH INTERNATIONAL TECHNOLOGY, EDUCATION AND DEVELOPMENT CONFERENCE / [ed] Chova, LG Martinez, AL Torres, IC, IATED-INT ASSOC TECHNOLOGY EDUCATION A& DEVELOPMENT , 2017, p. 1037-1041Conference paper (Refereed)
    Abstract [en]

    Higher education environments are becoming more and more diverse, regarding both gender and cultural background, which could pose significant challenges for both students and teachers. In order to raise the topic amongst STEM students, a lecture on Diversity has been implemented in the course Research Methodologies for Engineering Mechanics, where different concepts regarding equality have been introduced and unconscious bias have been explained to the students. The lecture was placed in the middle of the course so that students could reflect back on their previous evaluations and enable them to correct their biases in the second half of the course. Feedback of the whole course has also been compared between the 2016 and 2015 editions, where this lecture was not present. The results show that a lecture in Diversity and Equality is especially useful for female students, strongly supporting its inclusion in the course.

  • 4.
    Altimira, Mireia
    et al.
    Lund University.
    Fuchs, Laszlo
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Mechanics of Industrial Processes.
    Effect of fuel flexibility on cavitation in injector-like flows2014In: Proceedings of the 26th ILASS-Europe 2014, 2014Conference paper (Refereed)
  • 5.
    Altimira, Mireia
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Teaching Research Methodologies2016In: INTED2016 Proceedings, IATED , 2016Conference paper (Refereed)
    Abstract [en]

    This paper presents the methodology employed in the Research Methodology course, part of the Master Program in Engineering Mechanics of the Royal Institute of Technology (KTH). As a higher education institution, KTH aims at excellence in both generation and dissemination of knowledge. Even though these two activities are traditionally seen as independent –or even mutually exclusive-, there is a positive correlation between performance in research andin pedagogical activities, reinforced by the fact that inquiry-based or researchbased learning activities enhance deep learning among the students. The course Research Methodology in Engineering Mechanics poses a unique opportunity to engage the students to research in different areas through diversity-oriented learning activities.The course’s main learning outcome is that the students become acquainted with the most common concepts and research methodologies used in the fields of Fundamental Mechanics, Solid Mechanics, Fluid Mechanics, Acoustics and Biomechanics. After the completion of the course, the student should also be able to identify and analyze the methodologies in a given published work.The course consists of 9 lectures and a group project, with an estimation of the total dedication time of 80h (3hp). One lecture is focused on research ethics;while in the other 8 researchers from KTH present their areas of expertise, introducing the most relevant methodologies applied. The attendance is about40 students.In the last two years, and based on the course assessment survey, the structure of the course has been continuously shifting from traditional lectures to cover a broader range of teaching activities. In this way, different learning styles are covered and the learning outcomes can be achieved by as many students as possible. In this regard, traditional lectures are combined with problem-based or case-based lectures, and role-play. Additionally, in the content of the lectures we also try to keep a balance between experimental and numerical research methods of the different disciplines, in such a way that the students get a holistic view of the research in that particular field.This project involves reading a research journal article in the subject of engineering mechanics and presenting, in written and oral form, a critical analysis of the methodologies employed. In the beginning of their project, the students give an oral presentation of their article to another group. At the end of this activity, each group is asked to mention a positive aspect of the presentation they just heard and something that they believe should be improved. As an additional task, each group is asked to peer-review another group’s report. To do so, the students are given a document with some guidelines and evaluation criteria. Special instructions are given to make sure positive feedback is also included in the review. With this, the students get to read the work of others, learn to apply quality criteria and give feedback, and self-reflect on their own work after the review process.

  • 6.
    Altimira, Mireia
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Rivas, A.
    Ramos, J. C.
    Anton, R.
    On The Disintegration Of Fan-Shaped Liquid Sheets2012In: Atomization and sprays, ISSN 1044-5110, E-ISSN 1936-2684, Vol. 22, no 9, p. 733-755Article in journal (Refereed)
    Abstract [en]

    This paper presents a combined experimental and theoretical investigation of the disintegration of fan-shaped liquid sheets produced by industrial fan-spray atomizers. The disintegration regimes observed for different geometries and operating conditions are described, proving the paramount role of nozzle flow on the final characteristics of the spray produced. The concept of breakup length is redefined to account for the stochastic nature of liquid stream disintegration. An analogy is established between the breakup of a liquid sheet dominated by the wave mode and a radial sheet, obtaining good agreement with the experiments. However, in those cases where several disintegration regimes coexist, the breakup length cannot be given by an analytical expression. Finally, the influence of the disintegration regime on both the droplet size and the spatial distribution of the droplets is investigated, confirming the strong influence of rim breakup.

  • 7.
    Altimira, Mireia
    et al.
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Rivas, Alejandro
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Anton, Raul
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Sanchez Larraona, Gorka
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Ramos, Juan Carlos
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Fan-Spray Atomizers Analysis through Mathematical Modeling2007In: Proceedings of the 21st ILASS - Europe Meeting 2007, 2007Conference paper (Refereed)
    Abstract [en]

    The main objective of this work is to determine the most important design parameters in fan spray atomizers and their effect in the atomization features in order to provide a design tool for nozzle manufacturers. A mathematical model relating the geometry and operating conditions to the characteristics of the spray has been obtained and validated. Three different sub-models have been used in series, so that the results of one model become inputs of the next one, namely multiphase flow simulation, instability and break-up model and maximum entropy model. These have been joined achieving a global model of the whole primary atomization process.

  • 8.
    Altimira, Mireia
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Rivas, Alejandro
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Ramos, Juan Carlos
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Anton, Raul
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Disintegration regime of industrial fan-spray atomizers through CFD simulations2011In: ILASS – Europe 2011, 24th European Conference on Liquid Atomization and Spray Systems, Estoril, Portugal, September 2011, 2011Conference paper (Refereed)
    Abstract [en]

    Among all the literature devoted to the investigation of sprays, very few works deal with the influence of the nozzle’s geometry on the characteristics of the spray produced, even though it has been proved to play a crucial role in certain operating regimes. The present paper presents criteria for the determination of the dominant disintegration regime in industrial fan-spray atomizers through CFD simulations accounting for the atomizer’s geometry.

  • 9.
    Altimira, Mireia
    et al.
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Rivas, Alejandro
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Ramos, Juan Carlos
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Anton, Raul
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Linear spatial instability of viscous flow of a liquid sheet through gas2010In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 22, no 7Article in journal (Refereed)
    Abstract [en]

    The present paper focuses on the linear spatial instability of a viscous two-dimensional liquid sheet bounded by two identical viscous gas streams. The Orr–Sommerfeld differential equations and the boundary conditions of the flow configuration are numerically solved using Chebyshev series expansions and the collocation method. The strong dependence of the instability parameters on the velocity profiles is proven by using both quadratic and error functions to define the base flow in the liquid sheet and the gas shear layer. The sensitivity of the spatial instability growth rate to changes in the dimensionless parameters of the problem is assessed. Regarding the liquid sheet Reynolds number, it has been observed that, when this parameter increases, both the most unstable growth rate and the corresponding wavenumber decrease, whereas the cutoff wavenumber increases. The results of this analysis are compared with temporal theory through Gaster transformation. The effects liquid and gas viscosity have on instability are studied by comparing the instability curves given by the presented model with those from an inviscid liquid sheet and a viscous liquid sheet in an inviscid gaseous medium. The model presented in this paper features a variation in the cutoff wavenumber with all the governing parameters of the problem, whereas that provided by cases that account for an inviscid surrounding gas depends only on the liquid sheet Weber number and the ratio of gas to liquid densities. Results provided by the presented model have been experimentally validated and show that quadratic profiles have a greater capacity to predict the disturbance wavelength.

  • 10.
    Altimira, Mireia
    et al.
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Rivas, Alejandro
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Sanchez Larraona, Gorka
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Anton, Raul
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Ramos, Juan Carlos
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Characterization of fan spray atomizers through numerical simulation2009In: International Journal of Heat and Fluid Flow, ISSN 0142-727X, E-ISSN 1879-2278, Vol. 30, no 2, p. 339-355Article in journal (Refereed)
    Abstract [en]

    The present paper focuses on the mathematical modeling of industrial fan spray atomizers. The two-phase flow taking place inside the nozzle's tip and the exterior region near the outlet of three different industrial nozzle designs has been modeled and simulated. As a result, valuable information has been obtained regarding the influence of the inner geometry on the flow and also the formation and development of the liquid sheet. Characteristic magnitudes such as the discharge coefficient and the liquid sheet thickness factor have been obtained and validated through experimental measurements. The accumulation of liquid at the border of fan-shaped liquid sheets, also known as rim, has been studied in the analyzed designs, revealing the presence of a tangential velocity component in the liquid sheet and a relationship between the incoming flow rate of the rim and the angle of the liquid sheet. The dependence of the results on turbulence modeling has also been analyzed, drawing interesting conclusions regarding their influence on the liquid sheet mean flow characteristics and on the surrounding gas. Thus, the mathematical model developed has been proved to be a useful tool for nozzle manufacturers; it provides the most important characteristic parameters of the liquid sheet formed given certain nozzle geometry and, additionally, those data necessary to carry out studies of instability, breakup and atomization of the liquid sheet.

  • 11.
    Casanueva, Carlos
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Altimira, Mireia
    KTH, School of Engineering Sciences (SCI), Mechanics. Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Course design oriented towards degree objectives in higher education2016In: EDULEARN16 Proceedings, IATED , 2016, p. 1662-1669Conference paper (Refereed)
    Abstract [en]

    The goal of engineering education is to facilitate the learning of technical knowledge and understanding, skills, and attitudes required by students to become successful engineers. In the Swedish higher education system, the qualifications for a master degree in engineering are listed in the Higher Education Ordinance. Such qualifications, also called Degree Objectives, have to be fulfilled on a programme level, that is, throughout all courses that form the programme. This requires a high level of communication and collaboration between all course responsibles and the programme coordinator. At the same time, it also restricts the freedom in the design of each individual course, as they all have fit into a 2-year-long educational puzzle. Designing courses from their conception with a view on fulfilling all the degree objectives would be more effective in terms of programme coordination. However, it poses new challenges, since it requires that all degree objectives related to skills and attitudes be fulfilled in each and every course through its learning activities. Is there a way of designing the course activities in such a way that most degree objectives are covered, while respecting the diversity in learning styles and maturity level of the students, and promoting self-regulation? We explore the possibilities of this course design concept when framed within the CDIO Initiative. We analyse the relative importance of the different Degree Objectives in Swedish Higher Education, and how these can be introduced in the Intended Learning Outcomes of each individual course while keeping in mind the personal evolution of the students at different stages of their education.

  • 12.
    Heide, Jakob
    et al.
    KTH.
    Karlsson, Mikael
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).
    Altimira, Mireia
    KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).
    Numerical Analysis of Urea-SCR Sprays under Cross-Flow Conditions2017In: SAE technical paper series, ISSN 0148-7191, Vol. 2017-March, no MarchArticle in journal (Refereed)
    Abstract [en]

    Selective Catalytic Reduction (SCR) of NOx through injection of Urea-Water-Solution (UWS) into the hot exhaust gas stream is an effective and extensively used strategy in internal combustion engines. Even though actual SCR systems have 95-96% de-NOx efficiency over test cycles, real driving emissions of NOx are a challenge, proving that there is room for improvement. The efficiency of the NOx conversion is highly dependent on the size of UWS droplets and their spatial distribution. These factors are, in turn, mainly determined by the spray characteristics and its interaction with the exhaust gas flow. The main purpose of this study is to numerically investigate the sensitivity to the modelling framework of the evaporation and mixing of the spray upstream of the catalyst. The dynamics of discrete droplets is handled through the Lagrangian Particle Tracking framework, with models that account for droplet breakup and coalescence, turbulence effects, and water evaporation. All simulations have been run in the commercial code Ansys Fluent 16.0. Experimental validation of droplet size distribution is carried out through PDPA measurements. Through the present study we have identified suitable modelling setup that provides accurate results with a competitive computational cost. Results also show the importance of accounting for the effects of evaporation and turbulent fluctuations in the droplet phase.

  • 13.
    Kékesi, Timea
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Altimira, Mireia
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Amberg, Gustav
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Interaction between two deforming liquid drops in tandem and various off-axis arrangements subject to uniform flow2019In: International Journal of Multiphase Flow, ISSN 0301-9322, E-ISSN 1879-3533, p. 193-218Article in journal (Refereed)
    Abstract [en]

    A Volume of Fluid (VOF) method is applied to study the interaction between two liquid drops with the same initial diameter in uniform flow. Various arrangements of the drops are studied, based on two parameters, namely the initial separation distance and the angle between the line connecting the centres of the drops and the free-stream direction. Initial separation distances of 1.5–5 drop diameters, and angles between β=0 ∘ and 90° are considered. Simulations for a Weber number of We=20, two Reynolds numbers Re=20 and 50, and density and viscosity ratios in the range ρ * =20–80 and μ * =0.5–50 are performed. The movement of the secondary drop with respect to the primary drop, and estimates on the time required for the breakup of the secondary drop as compared to those observed for single drops are evaluated. It is found that the drops collide only in cases corresponding to the shortest initial displacements, while in others they deform and break up independently, similarly or identically to single drops. The same behaviour is reflected in the time required for breakup. Cases where the drops behave independently show breakup times close to those observed for single drops.

  • 14.
    Kékesi, Tímea
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.
    Altimira, Mireia
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Amberg, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Interaction between two deforming liquid drops in tandem and various off-axis arrangements subject to uniform flowManuscript (preprint) (Other academic)
    Abstract [en]

    A Volume of Fluid (VOF) method is applied to study the interaction between two liquid drops with the same initial diameter in uniform flow. Various arrangements of the drops are studied, based on two parameters, namely the initial separation distance and the angle between the line connecting the centres of the drops and the free-stream direction. Specifically, initial separation distances of l = 1.5 − 5D drop diamters, and angles between β = 0◦ − 90◦ are considered. Simulations for a Weber number of W e = 20, two Reynolds numbers Re = 20 and 50, and density and viscosity ratios in the range ρ∗ = 20 − 80 and μ∗ = 0.5 − 50 are performed. The movement of the secondary drop with respect to the primary drop, and the time required for the breakup of the secondary drop as compared to those observed for single drops are evaluated. It is found that the drops collide only in cases corresponding to the shortest initial displacements, while in others they deform and break up independently, similar or identical to single drops. The same behaviour is reflected in the time required for breakup. Cases where the drops behave independently show breakup times close to those observed for single drops.

  • 15.
    Montecchio, Francesco
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering. KTH, Dept Chem Engn, SE-10044 Stockholm, Sweden..
    Altimira, Mireia
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Andersson, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Fluid dynamics modelling of UV reactors in advanced oxidation processes for VOC abatement applications2019In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 369, p. 280-291Article in journal (Refereed)
    Abstract [en]

    The present work focuses on the treatment of VOC emissions from industrial processes, since they represent a very severe environmental hazard. For removing the VOC, an AOP (Advanced Oxidation Process) stage based on UV light and ozone was considered, analyzing the methods for the unit scale-up. An innovative CFD (Computational Fluid Dynamics) model, combining UV irradiation, reaction kinetics and fluid dynamics, describing the behavior of UV reactors in the laboratory scale, was developed. This model was verified against experimental results, displaying good agreement. Therefore, we concluded the CFD model could adequately describe relevant features regarding the performance of UV reactors. After analyzing the laboratory reactors, two designed and scaled up prototypes, were simulated using the CFD model. While the first prototype has a standard lamps configuration, the second presents an innovative lamps distribution. As for the laboratory cases, the most relevant features in terms of irradiation and reaction were described for the prototypes, comparing their performance. We evaluated both the overall VOC conversion and VOC conversion per UV lamp, analyzing the energy efficiency of each configuration with adequately accuracy. Therefore, we conclude the developed CFD model to be an important tool for reactor scale-up as a result of the good prediction of experimental results and the accurate description of the governing phenomena. By using the developed model, the scale-up process of UV reactors can be quickly improved, by screening various configurations with the simulator before testing them, saving significant time and effort in the development of full-scale reactors.

  • 16.
    Nygård, Alexander
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Altimira, Mireia
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Fuchs, Laszlo
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Disintegration Mechanisms of Intermittent Liquid Jets2016In: SAE International Journal of Fuels and Lubricants, ISSN 1946-3952, E-ISSN 1946-3960, Vol. 9, no 1, p. 91-99Article in journal (Refereed)
    Abstract [en]

    It has been observed that intermittent injection leads to improved spray characteristics in terms of mixing and gas entrainment. Although some experimental work has been carried out in the past, the disintegration mechanisms that govern the breakup of intermittent jets remain unknown. In this paper we have carried out a systematic numerical analysis of the breakup of pulsated jets under different injection conditions. More specifically, the duty cycle (share of active injection during one cycle) is varied, while the total cycle time is kept constant. The advection of the liquid phase is handled through the Volume of Fluid approach and, in order to provide an accurate, yet computationally acceptable, resolution of the turbulent structures, the implicit Large Eddy Simulation has been adopted. The results show that the primary disintegration results from a combination of stretching, collision and aerodynamic interaction effects. Moreover, there exists a strong coupling between stretching and collision as stretching makes the pulse thinner prior to the contact between pulses. In this work, the purpose is to study the collision contribution to breakup in terms of the near nozzle pulse disintegration rate. When approaching the low duty cycle limit, this effect is significant because of the lower liquid volume of the pulse. In contrast, for a high duty cycle, the stretching effect is limited and a wide tail region remains as an obstruction for following pulses. However, the integral momentum of the pulse is maintained to a larger degree that has an adverse effect on the outcome of the collision event.

  • 17.
    Nygård, Alexander
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Altimira, Mireia
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Fuchs, Laszlo
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Quantifying primary breakup in pulsating liquid2014In: / [ed] A. Eriksson, A. Kulachenko, M. Mihaescu and G. Tibert, 2014Conference paper (Refereed)
  • 18.
    Nygård, Alexander
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Mechanics of Industrial Processes.
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Mechanics of Industrial Processes.
    Altimira, Mireia
    Lund University.
    Fuchs, Laszlo
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Interaction between liquid pulses during intermittent injection2014In: Proceedings of the 26th ILASS-Europe 2014, 2014Conference paper (Refereed)
  • 19.
    Olin, Linus
    et al.
    KTH.
    Altimira, Mireia
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Danielsson, Jonas
    Rosén, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Numerical modelling of spray sheet deflection on planing hulls2017In: Journal of Engineering for the Maritime Environment (Part M), ISSN 1475-0902, E-ISSN 2041-3084, Vol. 231, no 4, p. 811-817Article in journal (Refereed)
    Abstract [en]

    This paper considers the modelling of spray formation on planing hulls. The focus is on assessing the applicability of the prevailing theories and two-dimensional and three-dimensional Computational Fluid Dynamics (CFD) simulations in the investigation of different design factors for a novel spray deflection concept. The spray deflection concept is presented and its performance is evaluated by comparison with traditional spray rails. It is found that the prevailing theory where the spray field of a planing hull is represented by a two-dimensional flat planing plate will overestimate the spray thickness, whereas the theories that are based on wedge impact are correlating well with the results from the CFD simulations. Compared to a bare hull, adding spray deflectors reduces the viscous resistance by 28% for the studied cases. The spray deflectors further redirect the spray aftwards which reduce the total drag an additional 4%. The paper also discusses various aspects on CFD modelling of spray formation.

  • 20.
    Rivas, Alejandro
    et al.
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Altimira, Mireia
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Sanchez Larraona, Gorka
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Ramos, Juan Carlos
    Mech. Eng. Dept., Tecnun (Univ. of Navarra).
    Analysis of Liquid-Gas Flow near a Fan-Spray Nozzle Outlet2006In: Conference on Modelling Fluid Flow (CMFF’06): The 13th International Conference on Fluid Flow Technologies Budapest, Hungary, September 6-9, 2006, 2006Conference paper (Refereed)
    Abstract [en]

    This paper reports the results of mathematical modelling and simulation of two-phase flow near the outlet of six different industrial fan-spray atomizers under different operating conditions.

    The Finite Volume Method, implemented in the commercial code, Fluent V.6.2, has been used to solve the mathematical model numerically, whilst the Volume of Fluid (VOF) approach has been employed to track the interface between liquid and gas. Surface tension effects have been included using the Continuum Surface Force method (CSF).

    Results from simulation have been validated with experimental data and compared with those from previous works. Interesting conclusions about sheet thickness, velocity and vorticity of the flow have been obtained; some of them differ from hypotheses assumed in previous works. These conclusions may reflect the way in which break-up models are used to obtain drop size and break-up length.

  • 21.
    Wu, Hongwen
    et al.
    KTH.
    Brunberg, Johan
    Altimira, Mireia
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Bratt, Niclas
    Nyberg, Henrik
    Cronhjort, Andreas
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Peciura, Justinas
    Semi-Empirical CFD Transient Simulation of Engine Air Filtration Systems2016In: SAE International Journal of Passenger Cars - Mechanical Systems, ISSN 1946-3995, E-ISSN 1946-4002, Vol. 9, no 1, p. 310-320Article in journal (Refereed)
    Abstract [en]

    To improve fuel efficiency and facilitate handling of the vehicle in a dense city environment, it should be as small as possible given its intended application. This downsizing trend impacts the size of the engine bay, where the air filter box has to be packed in a reduced space, still without increased pressure drop, reduced load capacity nor lower filtering efficiency. Due to its flexibility and reduced cost, CFD simulations play an important role in the optimization process of the filter design. Even though the air-flow through the filter box changes as the dust load increases, the current modeling framework seldom account for such time dependence. Volvo Car Corporation presents an industrial affordable model to solve the time-dependent dust load on filter elements and calculate the corresponding flow behavior over the life time of the air filter box. The implemented semi-empirical simulation algorithm integrates several sub-models derived from different studies on flows over pleated filters. This work also introduces an experimental method to record the dust pattern on the filter element in order to validate the numerical results. Test results show that the overall dust load as well as its distribution within the filter element can be estimated accurately.

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