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  • 1.
    Cervantes, Michel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Jansson, Ida
    Jourak, Amir
    Glavatskih, Sergei
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Aidanpää, Jan-Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Porjus U9A full-scale hydropower research facility2008Ingår i: Hydro technology and the evironment for the new century: 24th IAHR Symposium on Hydraulic Machinery and Systems, October 27 - 31, 2008, Foz do Iguassu, Brazil, Foz do Iguassu, 2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hydropower still faces complex scientific and technical challenges in order to secure the availability and reliability of the power plants despite more than a century of development. The main challenge is due to new market constrains such as electrical market deregulation and introduction of renewable sources of energy. The major problem is related to the dynamic of the rotor involving several fields: hydraulics, power engineering and mechanics. On the other side, the large and growing hydropower world market represents an opportunity for technically advanced companies offering better efficiency. The difficulty to scale rigorously any technical advance makes full-scale experiment a necessity. World unique facilities are available at Porjus, Sweden, for this purpose. The Porjus Hydropower Centre is composed of a Francis (U8) and a Kaplan (U9) turbine of 10 MW, each exclusively dedicated to education, research and development. In order to further investigate specific issues related to availability and reliability, a project was initiated in 2006. The main objective is to make U9 a full-scale hydropower laboratory able firstly to furnish the necessary data for the development of rotor-dynamic models but also turbines and bearings. To this purposes more than 200 sensors have been installed to measure displacements, forces, pressure, film thickness, strains... The work presents an overview of the newly upgrade facility as well as some of the problems faced during the instrumentation of the machine.

  • 2.
    Herrmann, Inga
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Jourak, Amir
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Gustafsson, Jon Petter
    Department of Land and Water Resources Engineering, Royal Institute of Technology.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Modeling phosphate transport and removal in a compact bed filled with a mineral-based sorbent for domestic wastewater treatment2013Ingår i: Journal of Contaminant Hydrology, ISSN 0169-7722, E-ISSN 1873-6009, Vol. 154, s. 70-77Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Phosphorus filter units containing mineral-based sorbents with a high phosphate (PO4) binding capacity have been shown to be appropriate for removing PO4 in the treatment of domestic wastewater in on-site facilities. However, better understanding of their PO4 removal mechanisms, and reactions that could lead to the formation of PO4 compounds, is required to evaluate the potential utility of candidate sorbents. Models based on data obtained from laboratory-scale experiments with columns of selected materials can be valuable for acquiring such understanding. Thus, in this study the transport and removal of PO4 in experiments with a laboratory-scale column filled with a commercial silicate-based sorbent were modeled, using the hydro-geochemical transport code PHREEQC. The resulting models, that incorporated the dissolution of calcite, kinetic constrains for the dissolution of calcium oxide (CaO) and wollastonite (CaSiO3), and the precipitation of amorphous tricalcium phosphate, Ca3(PO4)2, successfully simulated the removal of PO4 observed in the experiments.

  • 3.
    Herrmann, Inga
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Jourak, Amir
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Enhancing the reliability of laboratory phosphorus filter tests: effect of influent properties and interpretation of effluent parameters2014Ingår i: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 225, nr 1, artikel-id 1766Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Filtration can be a convenient technique for removing phosphorus (P) at on-site wastewater treatment facilities to recycle this non-renewable element. When testing potentially suitable materials for these filters, the properties of the influent and the method used to analyse measured effluent concentrations both affect the P binding capacity determined in filter tests and therewith filter longevity predictions. At present, there is a lack of robust methods for material investigation and filter test interpretation. This study was conducted to investigate the effect of inflow PO4-P concentrations (concentration) and hydraulic surface load (load) on P binding capacity and to analyse possible interpretations of laboratory filter tests. A 22 factorial experiment with replicates was performed on the calcium-based filter material Filtra P. The investigated concentrations ranged from 12 to 50 mg L-1 and loads from 419 to 1,023 L m-2 day-1. P binding capacity (calculated by mass balance including data until PO4-P breakthrough point) was negatively affected by concentration and positively affected by load, with the effect of concentration being slightly greater. Depending on the factors' settings and on the method of evaluation (i.e. analysing all pre-saturation data or considering only pre-breakthrough results), the total measured P binding capacity varied between 2.2 and 9.0 g kg-1. The part of the breakthrough curve between the breakthrough point and saturation contributed significantly to the measured P binding capacity, and it took about three times longer for the filters to become saturated than to reach breakthrough. Furthermore, a considerable amount of P that had reacted with the filter material was washed out of the filters as particle-bound P. This indicates that it is important to determine both the PO4-P and the particle-bound P phases in the filter effluent

  • 4.
    Herrmann, Inga
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Jourak, Amir
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    The effect of hydraulic loading rate and influent source on the binding capacity of phosphorus filters2013Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sorption by active filter media can be a convenient option for phosphorus (P) removal and recovery from wastewater for on-site treatment systems. There is a need for a robust laboratory method for the investigation of filter materials to enable a reliable estimation of their longevity. The objectives of this study were to (1) investigate and (2) quantify the effect of hydraulic loading rate and influent source (secondary wastewater and synthetic phosphate solution) on P binding capacity determined in laboratory column tests and (3) to study how much time is needed for the P to react with the filter material (reaction time). To study the effects of these factors, a 22 factorial experiment with 11 filter columns was performed. The reaction time was studied in a batch experiment. Both factors significantly (α = 0.05) affected the P binding capacity negatively, but the interaction of the two factors was not significant. Increasing the loading rate from 100 to 1200 L m-2 d-1 decreased P binding capacity from 1.152 to 0.070 g kg-1 for wastewater filters and from 1.382 to 0.300 g kg-1 for phosphate solution filters. At a loading rate of 100 L m-2 d-1, the average P binding capacity of wastewater filters was 1.152 g kg-1 as opposed to 1.382 g kg-1 for phosphate solution filters. Therefore, influent source or hydraulic loading rate should be carefully controlled in the laboratory. When phosphate solution and wastewater were used, the reaction times for the filters to remove P were determined to be 5 and 15 minutes, respectively, suggesting that a short residence time is required. However, breakthrough in this study occurred unexpectedly quickly, implying that more time is needed for the P that has reacted to be physically retained in the filter.

  • 5.
    Herrmann, Inga
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Jourak, Amir
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Flow design of phosphorus filters2012Konferensbidrag (Refereegranskat)
  • 6.
    Herrmann, Inga
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Jourak, Amir
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Phosphorus binding to Filtra P in batch tests2012Ingår i: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 33, nr 9, s. 1013-1019Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent guidelines from the Swedish Environmental Protection Agency recommend stricter regulations for phosphorus (P) reduction in small-scale wastewater treatment, which raises the need for additional and novel treatment steps in small-scale facilities. Following a biological pre-treatment, filter systems can be a convenient option. In this study, the P binding capacity of the filter material Filtra P was investigated in batch tests. The batch test method was evaluated with respect to the effects of liquid-to-solid ratio and particle size on P binding capacity. For initial concentrations (ci ) between 3 and 100 mg L−1, the P in the solution was completely and rapidly bound to the material, indicating that Filtra P was an efficient substrate for this process. The maximum amount of bound P was 4.3 ± 0.64 g kg−1 at c i = 300 mg L−1. P binding capacity and turbidity measured in the supernatant correlated positively. Turbidity was probably caused by calcium-P-precipitates suggesting precipitation was the major removal mechanism. Neither liquid-to-solid ratio, nor particle size, affected P binding capacity significantly (α = 0.05) at ci  = 1000 mg L−1, confirming that the conditions used in the batch tests were appropriate. In full-scale applications, the precipitate formed may be at risk of being washed out of the filter, leading to low total P reduction and recovery.

  • 7.
    Jourak, Amir
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Modeling Flow and Solute Transport in Packed Beds: Applications in On-site Wastewater Treatment Systems2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The use of separate phosphorus (P) filter units containing replaceable filter materials with a high P binding capacity have been suggested as an appropriate passive method to treat the P from pre-treated domestic wastewater in on-site facilities. A large number of materials have been identified and suggested as being potentially suitable for such filters. Despite the numerous experimental works with these P filter materials there is still a lack of systematic effort to model the P transport and removal in a packed-bed column experiment filled with such materials. Such a methodology is useful for assessing the performance and longevity of a material. Such a model could also have the potential to be used for scale-up and optimization of operational parameters.The overall objective of this thesis is to investigate and develop methods that can be used to model the flow and solute transport in packed beds in general, as well as dissolved P transport and removal in a laboratory-scale packed bed that is filled with P filter materials. Two different model approaches are investigated: discrete and continuum modeling. In the discrete modeling approach, a packed bed is modeled as a porous medium that consists of thousands of discrete particles. In the continuum modeling approach, a packed bed is considered as a single continuum model with effective parameters such as average pore-water velocity and dispersion coefficients describing the movement of a solute in the packed-bed model.In the discrete modeling approach, two- and three-dimensional randomly packed beds of inert cylinders and spheres are considered, respectively. The flow and nonreactive solute transport are modeled in packed-bed models. Voronoi diagrams are applied to discretize the system into cells that each contains one particle. The whole flow pattern for packed-bed models at low particle Reynolds number is obtained by minimization of the dissipation rate of energy. The effective dispersion coefficients that are derived from packed-bed models are in excellent agreement with the previous data in the literature, showing that these methods can successfully model the flow and solute transport in packed beds. One main advantage of the present method is to make it possible to perform pore-scale simulations of flow, mass and heat transfer in porous media and packed beds with many particles. Moreover, these models facilitate the study of the effects of different packing parameters, such as particle-size distribution, porosity and packing structure on the dispersion coefficients. For example, one result is that an increase in the width of the particle-size distribution increases the dispersion coefficients at high velocities. This discrete modeling approach to solve transport problems in porous media is generic and is applicable for studying heat transfer, drying processes, internal erosion in embankment dams, etc.In the continuum modeling approach, the Langmuir isotherm is fitted to measurements obtained from batch experiments. This Langmuir isotherm is further coupled with the one-dimensional advection-dispersion equation and can successfully model the dissolved P effluent curve of a laboratory- scale column experiment. In the next step, the hydro-geochemical transport code PHREEQC is used to model the transport of dissolved P, dissolution of reactive minerals from a calcium-silicate sorbent and precipitation of P- products in a laboratory-scale column experiment. This methodology can successfully simulate the possible dissolved P removal scenario that occurs in the laboratory-scale column containing the calcium-silicate sorbent.

  • 8.
    Jourak, Amir
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Phosphorus transport and reduction in compact-bed filters: simulations and experiments2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Excessive release of phosphorus from the effluent of on-site sanitation facilities to the environment is one source of aquatic pollution. The primary effect of excess phosphorus in the aquatic environment is eutrophication. In Sweden, there are about one million private on-site wastewater treatment facilities, half of which are considered unacceptable by the Swedish Environmental Protection Agency (SEPA). Recent guidelines issued by SEPA recommended total phosphorus reduction of 70-90 % in wastewater in small scale treatment facilities. Using reactive filter materials as compact filter systems following a biological pretreatment can be a convenient option for upgrading the present on-site sewage treatment facilities. Research on reactive filter materials has been undertaken in many different ways as there is no standard method for such investigations. Therefore, there is a need to develop methods and models to evaluate the reduction capacity and predict the longevity of potential reactive filter materials.In the first part of this thesis a filter material Filtra P (Nordkalk, Finland) is investigated. The phosphorus sorption characteristics of Filtra P were investigated in batch and column experiments. The batch test method was evaluated with respect to the effects of liquid-to-solid ratio and particle size on phosphorus sorption. Column experiments were carried out at different flow rates and phosphate (PO4-P) feed concentrations. The experimental data obtained from batch and column experiments were used to investigate the feasibility of modeling PO4-P breakthrough curves in fixed-bed columns by means of the convection-dispersion equation and a Langmuir isotherm. The model successfully predicted the PO4-P breakthrough curves for the columns with low influent concentration (11 mg dm-3), which is within the range normally found in wastewater (5-15 mg dm-3). Experimental observations however yield that the possibility to combine the convection-dispersion equation with a model accounting for precipitation of calcium-phosphate compounds in the bulk should be examined.The second part of the thesis focuses on dispersion in laminar flow through a randomly packed porous-medium model. The study of dispersion in flow through porous media is an important issue in many branches of science and engineering and has direct applications in several industries. For example, dispersion occurs in the disposal of sewage waste into aquifers and flow through reactive compact-bed filters that are used for on-site sanitation systems. In order to shed light on this phenomenon, a detailed longitudinal and transverse dispersion numerical experiments were performed in two-dimensional (2D) randomly packed beds of thousands of circular particles in a laminar flow regime. The calculated longitudinal and transverse dispersion coefficients were presented as Peclet numbers based on longitudinal and transverse dispersion coefficients versus Peclet number based on molecular diffusion coefficient, and were compared to three-dimensional (3D) experimental data available in the literature. It was found that at very low superficial liquid velocities both longitudinal and transverse dispersions were governed by molecular diffusion. Based on the comparisons between numerical results obtained from the 2D model to the 3D experimental data, it was found that the present 2D approach to study the longitudinal dispersion in flow through porous media can be considered to be acceptable.The present numerical data may be used to estimate the longitudinal and transverse dispersion coefficients in a 2D process by which one fluid is displaced from a porous medium by a second fluid which is miscible with the first in a laminar flow regime.

  • 9. Jourak, Amir
    et al.
    Cervantes, Michel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Cupillard, Samuel
    Glavatskih, Sergei
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    CFD analysis of a journal bearing with a microgroove on the shaft2008Ingår i: Proceedings of the 19th International Symposium on Transport Phenomena (ISTP-19): Reykjavik, Iceland, August 17-21, 2008 / [ed] Sigurdur Brynjolfsson; Olafur Petur Palsson; Jong H. Kim, University of Iceland, Faculty of Industrial Engineering, Mechanical Engineering and Computer Science , 2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    Journal bearings are used in many applications. An increase of their load carrying capacity and/or decrease of their losses may allow for savings of an enormous amount of energy. One way to enhance the characteristics of journal bearings is to modify the surface texture of the stator. The purpose of the present study is to investigate the influence of a textured rotor on journal bearing characteristics. Computational Fluid Dynamics is used to model the flow between the rotor and the journal. The full Navier-Stokes equations are solved under unsteady conditions with the commercial software ANSYS CFX 11. A two-dimensional geometry is used to model the bearing. In order to make a simulation, a separate rotor and stator are made and are attached to each other using a rotor-stator interface. Firstly, a single mesh for the smooth journal bearing is used to evaluate possible numerical artefacts created by the interface. The results illustrate a difference of 2.8 % in the load carrying capacity. Simulation with a dimpled rotor followed. Comparison between a dimpled rotor and smooth rotor shows no significant increase in load carrying capacity of the journal bearing when thermal effects are not taken into account.

  • 10.
    Jourak, Amir
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Frishfelds, Vilnis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Hellström, J. Gunnar I.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Derivation of dispersion coefficients in large random arrays of spheres and cylinders2012Konferensbidrag (Refereegranskat)
  • 11. Jourak, Amir
    et al.
    Frishfelds, Vilnis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Hellström, J. Gunnar I.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Numerical derivation of dispersion coefficients for flow through three-dimensional randomly packed beds of monodisperse spheres2014Ingår i: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 60, nr 2, s. 749-761Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The longitudinal (DL) and transverse (DT) dispersion coefficients for flow through randomly packed beds of discrete monosized spherical particles are studied. The three-dimensional (3-D) porous-medium model consists of thousands of spherical particles that are divided into cells using Voronoi diagrams. The relationship between the variation of the dual stream function and the vorticity between neighboring particles is derived using Laurent series. The whole flow pattern at low particle Reynolds number is then obtained by minimization of the dissipation rate of energy with respect to the dual stream function. The DL is obtained by fitting the resulting effluent curve to a 1-D solution of a continuous model. The DT is obtained by fitting the numerical concentration profile to an approximate 2-D solution. The derived DL and DT values are in agreement with 3-D experimental data from the literature enabling a study of the effects of pore structure and porosity on DL and DT.

  • 12.
    Jourak, Amir
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Frishfelds, Vilnis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Hellström, J. Gunnar I.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Herrmann, Inga
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Longitudinal dispersion coefficient: effects of particle-size distribution2013Ingår i: Transport in Porous Media, ISSN 0169-3913, E-ISSN 1573-1634, Vol. 99, nr 1, s. 1-16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of particle-size distribution on the longitudinal dispersion coefficient (DL) in packed beds of spherical particles are studied by simulating a tracer column experiment. The packed-bed models consist of uniform and different-sized spherical particles with a ratio of maximum to minimum particle diameter in the range of 1–4. The modified version of Euclidian Voronoi diagrams is used to discretize the system of particles into cells that each contains one sphere. The local flow distribution is derived with the use of Laurent series. The flow pattern at low particle Reynolds number is then obtained by minimization of dissipation rate of energy for the dual stream function. The value of DL is obtained by comparing the effluent curve from large discrete systems of spherical particles to the solution of the one-dimensional advection-dispersion equation. Main results are that at Peclet numbers above 1, increasing the width of the particle-size distribution increases the values of DL in the packed bed. At Peclet numbers below 1, increasing the width of the particle-size distribution slightly lowers DL.

  • 13.
    Jourak, Amir
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Frishfelds, Vilnis
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Herrmann, Inga
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Modeling of phosphate removal by fitra P in fixed-bed columns2011Ingår i: 2nd International Conference on Environmental Science and Technology , ICEST 2011 / [ed] Saji Baby; Bogdan Zygmunt, China, 2011, Vol. 2, s. 241-248Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hydropower still faces complex scientific and technical challenges in order to secure the availability and reliability of the power plants despite more than a century of development. The main challenge is due to new market constrains such as electrical market deregulation and introduction of renewable sources of energy. The major problem is related to the dynamic of the rotor involving several fields: hydraulics, power engineering and mechanics. On the other side, the large and growing hydropower world market represents an opportunity for technically advanced companies offering better efficiency. The difficulty to scale rigorously any technical advance makes full-scale experiment a necessity. World unique facilities are available at Porjus, Sweden, for this purpose. The Porjus Hydropower Centre is composed of a Francis (U8) and a Kaplan (U9) turbine of 10 MW, each exclusively dedicated to education, research and development. In order to further investigate specific issues related to availability and reliability, a project was initiated in 2006. The main objective is to make U9 a full-scale hydropower laboratory able firstly to furnish the necessary data for the development of rotor-dynamic models but also turbines and bearings. To this purposes more than 200 sensors have been installed to measure displacements, forces, pressure, film thickness, strains... The work presents an overview of the newly upgrade facility as well as some of the problems faced during the instrumentation of the machine.

  • 14.
    Jourak, Amir
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Frishfelds, Vilnis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Herrmann, Inga
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    The calculations of dispersion coefficients inside two-dimensional randomly packed beds of circular particles2011Konferensbidrag (Refereegranskat)
  • 15.
    Jourak, Amir
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Frishfelds, Vilnis
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Herrmann, Inga
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    The calculations of dispersion coefficients inside two-dimensional randomly packed beds of circular particles2013Ingår i: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 59, nr 3, s. 1002-1011Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The longitudinal (DL) and transverse (DT) dispersion coefficients in two-dimensional (2D) randomly packed beds of circular particles in a laminar flow regime are derived. A 2D discrete system of particles is divided into cells using modified Voronoi diagrams. The relationship between the variation of the stream function and the averaged vortictiy is obtained from Computational Fluid Dynamics simulations. The whole flow pattern is then obtained by using the principle of energy dissipation rate minimization. The obtained values of DL agree well with 3D experimental data for all velocities investigated. At very high velocities, DT in 2D appears to be higher than 3D experimental data. In addition, the effects of particle size distribution, packing structure, and porosity on the DL and DT were studied. One result was that an increase in the width of the particle size distribution resulted in higher values of DL and DT at high velocities.

  • 16.
    Jourak, Amir
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Herrmann, Inga
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Frishfelds, Vilnis
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Modelling of phosphate removal by Filtrap in a fixed-bed column2010Konferensbidrag (Övrigt vetenskapligt)
  • 17.
    Jourak, Amir
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, Staffan
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Herrmann, Inga
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Modelling of the transport of substances through reactive porous materials2009Ingår i: Svenska mekanikdagarna: Södertälje 2009, Svenska nationalkommittén för mekanik , 2009, s. 102-Konferensbidrag (Övrigt vetenskapligt)
1 - 17 av 17
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