Energía

An experimental study is presented on the characterization of the noise transmission properties of the duct junctions used in ventilation and air-conditioning air circuits, assumed as three-port acoustic systems with plane-wave sound propagation. The procedure requires the measurement and post-processing of the transfer functions between the control signals of three loudspeakers, one at each branch, and the sound pressure signal recorded at six positions (two-microphone technique). The result is the scattering matrix, which contains three reflection coefficients and six transmission coefficients. Experiments were conducted on junctions of ducts with the same diameter, with three different deviation angles for the branch take-off. Besides, several different airflow conditions were imposed for each geometrical configuration. This paper describes the methodology used and the results obtained for the cases tested, and discusses the effect of the different factors involved in the noise transmission through the duct divisions. r (J.L. Parrondo). performed by accumulating sound energy attenuations and re-generations along the air circuit, with no account of sound reflections.

The impeller of a centrifugal pump experiences a significant radial load when operating at off-design conditions. Its average magnitude can be reasonably estimated at the design stage by existing formulas. In contrast, the unsteady component is difficult to estimate since it is affected by the transient properties of the flow. This paper explores the use of a commercial CFD code to estimate the total radial load on the impeller of two test pumps. The full 3D-URANS equations were solved for several flow rates between 10%-130% of rated conditions. The predictions were validated with experimental data of global characteristics and unsteady pressure distribution round the impeller. The code was used to estimate the total radial load (steady and unsteady components) on the impellers as a function of flow rate. It was observed that the unsteady component can represent about a 40%-70% of the average magnitude when operating at off-design conditions.

Experimental and numerical studies are presented on the steady and unsteady radial forces produced in a single volute vaneless centrifugal pump. Experimentally, the unsteady pressure distributions were obtained using fast response pressure transducers. These measurements were compared with equivalent numerical results from a URANS calculation, using the commercial code FLUENT. Two impellers with different outlet diameters were tested for the same volute, with radial gaps between the blade and tongue of 10.0% and 15.8% of the impeller radius, for the bigger and smaller impeller diameters, respectively. Very often, pump manufacturers apply the similarity laws to this situation, but the measured specific speeds in this case were found to be slightly different. The steady radial forces for the two impellers were calculated from both the measured average pressure field and the model over a wide range of flow rates in order to fully characterize the pump behavior. Again, a deviation from the expected values applying the similarity laws was found. The data from the pressure fluctuation measurements were processed to obtain the dynamic forces at the blade passing frequency, also over a wide range of flow rates. Afterwards, these results were used to check the predictions from the numerical simulations. For some flow rates, the bigger diameter produced higher radial forces, but this was not to be a general rule for all the operating points. This paper describes the work carried out and summarizes the experimental and the numerical results, for both radial gaps. The steady and unsteady forces at the blade passing frequency were calculated by radial integration of the pressure distributions on the shroud side of the pump volute. For the unsteady forces, the numerical model allowed a separate analysis of the terms due to the pressure pulsations and terms related to the momentum exchange in the impeller. In this way, the whole operating range of the pump was studied and analyzed to account for the static and dynamic flow effects. The unsteady forces are very important when designing the pump shaft as they can produce a fatigue collapse if they are not kept under a proper working value.

This paper presents the functional characterization of a centrifugal pump used as a turbine. It shows the characteristic of the machine involved at several rotational speeds, comparing the respective flows and heads. In this way, the influence of the rotational speed on efficiency as well as obtaining characteristic at constant head and runaway speed can be observed. Also the forces actuating on the impeller were studied. An uncertainty analysis was made to assess the

This paper proposes and develops a circuit-based model aiming to simulate variable magnetic power elements in power electronic converters. The derived model represents the magnetic element by a reluctance-based equivalent circuit. The model takes into consideration device core losses, with the main emphasis given to hysteresis losses, which are modeled using the Jiles-Atherton model. The core loss model is further validated on different ferromagnetic materials to prove its range of applicability. The winding losses of the magnetic device are also taken into consideration, which are obtained using Dowell empirical formulas. In addition, the frequency dependence of the device losses is also considered. The proposed modeling procedure has been applied to study and characterize a double E-core variable power inductor structure in a 1 kW SiC full bridge DC-DC converter. The procedure has been verified by comparing the simulation results to the experimental measurements, confirming the validity and accuracy of the full circuit-based model.

This work presents a fault ride-through control scheme for a non-isolated power topology used in a hybrid energy storage system designed for DC microgrids. The hybrid system is formed by a lithium-ion battery bank and a supercapacitor module, both coordinated to achieve a high-energy and high-power combined storage system. This hybrid system is connected to a DC bus that manages the power flow of the microgrid. The power topology under consideration is based on the buck-boost bidirectional converter, and it is controlled through a bespoke modulation scheme to obtain low losses at nominal operation. The operation of the proposed control scheme during a DC bus short-circuit failure is shown, as well as a modification to the standard control to achieve fault ride-through capability once the fault is over. The proposed control provides a protection to the energy storage systems and the converter itself during the DC bus short-circuit fault. The operation of the converter is developed theoretically, and it has been verified through both simulations and experimental validation on a built prototype.

This paper studies a new launching method for steel bridges based on a self-supporting deck system. This new and patent-protected procedure is able to launch bridges of a span length up to 150 m, in an economical and sustainable way. The use of the last span segments to reinforce the critical sections during launching replaces other conventional temporary means applied nowadays. The main objective of this research paper is to numerically analyse the best double deck configuration as well as to define an approach to stiffener distribution in order to avoid the patch loading phenomenon in the slender webs. With this in mind, the pre-design of a triangular cell along the low flange of each web is presented. A three dimensional finite element model (FEM) is built and the design of experiments technique (DOE) is applied to obtain the best bridge configuration. This new construction method can be used together with a continuous launching system in order to increase the velocity of the whole operation and to improve safety during launching. Very good results have been obtained, in terms of deflection, patch loading resistance and vertical load on the pushing device. The comparison with other different construction systems and the application to a real case allows us to ensure the viability of the method described.

Resumen I ________________________________ Nuevo método de lanzamiento de puentes metálicos basado en doble cajón colaborante: simulación numérica estructural y experimentación aerodinámica. RESUMEN La construcción de un puente es la etapa más comprometida de su vida; se dice que si un puente es capaz de superar su fase de ejecución, entonces, puede permanecer durante siglos (así reza, al menos, la inscripción en el arco conmemorativo que se levanta sobre el Puente de Alcántara, desde hace casi 2000 años). Y esto es particularmente cierto en determinadas tipologías estructurales, tales como los puentes arco, los puentes atirantados y en los realizados mediante la técnica de empuje o lanzamiento. La razón, amén de las múltiples vicisitudes que caracterizan ese periodo, es que, en él, la estructura debe soportar diferentes esfuerzos a medida que avanza el proceso de lanzamiento y, en ocasiones, superiores a los que deberá hacer frente en fase de servicio. Este hecho hace que, en la actualidad, este eficaz procedimiento de construcción se encuentre limitado por la luz máxima del puente a empujar. Agradecimientos V ________________________________ Nuevo método de lanzamiento de puentes metálicos basado en doble cajón colaborante: simulación numérica estructural y experimentación aerodinámica. AGRADECIMIENTOS A mis directores de tesis Daniel Castro y Juan José del Coz, por la oportunidad que en su día me brindaron y por su continua ayuda, aliento y amistad. A mis compañeros de GICONSIME (Universidad de Oviedo) Mar Alonso y Felipe Álvarez. A los compañeros de GITECO, Natalia, Silvia y todos los demás. A Francisco Ballester, Catedrático del Área.

An alternative modelling for flexible membranes anchored to the ground for soil slope stabilisation is presented using Smoothed-Particle Hydrodynamics to model the unstable ground mass in a soil slope, employing a dynamic solve engine. A regression model of pressure normal to the ground, , and also membrane deflection, , have been developed using Design of Experiment. Finally, a comparison between the pressure obtained from numerical simulation and from a limit equilibrium analysis considering infinite slope has been carried out, showing differences in the results, mainly due to the membrane stiffness.

Tidal energy has significant potential yet to be developed. One of the key areas of the research lines being developed is the ability to perform accurate computational models in order to make a full appraisal of kinetic energy potential in different areas through tide movements. So far, due to the limitations of computational resources and the extension of the geographical domains, existing models have manly used simplifications such as low resolution mesh sizes and velocity profile approximations in the vertical dimension. The investigation put forward includes a high resolution two dimensional equivalent model of the zone studied using a longitudinal section with depth and length dimensions, as well as a simulation methodology to study the velocity field in different sections. The model can be used in cases of channels of high width compared to the depth. With such data, kinetic power and energy of tidal currents can be predicted. Both, model and methodology have been applied and validated to the specific case of the estuary of Avilés port, thereby obtaining a new perspective in the hydrodynamic study as well as a tidal current energy potential assessment.

Agente: No consta 54 Título: Dispositivo de desplazamiento continuo de estructuras. 57 Resumen: Dispositivo de desplazamiento continuo de estructuras. Un dispositivo de desplazamiento continuo de una estructura por medio de una fuerza de fricción, que comprende unos accionamientos (19) configurados para girar unos piñones (6) en dos sentidos, donde dichos piñones (6) a su vez arrastran unas cadenas de tracción (4). El dispositivo comprende también una cadena de eslabones de apoyo (2) de gran rigidez diseñados para soportar cargas verticales, unida a las cadenas de tracción (4) mediante unos bulones (3) que soportan cargas verticales y horizontales.

 Background: This patent is based on the combination of caterpillar mechanisms and conveyors. Caterpillar tracks support heavy loads and adapt this support according to the ground conditions. Conveyors displace distributed loads continuously and bidirectionally using the force of friction. This paper describes a revision of previous patents related to this innovative design.  Objective: This paper presents an innovative patent to continuously displace heavy structures safely. The mechanism was patented in 2011 as Spanish Patent ES 2367737. The combination of these mechanisms provides the design of this patent to displace heavy structures continuously and bidirectionally, while adapting to the deflection of the structures.  Method: The most important elements of this patent are detailed in the paper. The most innovative component is the load compensation system, which increases the safety of the displacement of heavy structures. This system controls the load applied on the mechanism, and the displacement can be stopped before the collapse of the heavy structure.  Results: An application of the patent for launching bridges using the Incremental Launching Method is presented. This mechanism is used to displace heavy structures using the force of friction.  Conclusion: The patented mechanism is an original contribution for the displacement of heavy structures continuously and bidirectionally. The patent can be used to launch bridges, improving the efficiency, sustainability, and safety of current systems.

Air pollution is one of the consequences of the industrial development, which causes a lot of health and environmental problems. For these reasons, the quality of the air is one of the major concerns of regional, national and European governments. All of them are developing strict normative to reduce the emissions of contaminants. The quality of the air can be analysed by means of numerical simulations. In this paper, a methodology based on Computational Fluid Dynamics (CFD) is described. This technique allows evaluating the dispersion of industrial-type air pollutants in a relatively large area, taking into account the orography, buildings and so on. Also, specific models are studied in order to consider the specific characteristics of the industrial contaminants and particles.

Tides can be a vast and predictable source of renewable energy. Due to the solar and lunar influx on our planet, they move large amounts of water periodically, and this energy can be harnessed using devices designed and positioned adequately, such as current turbines. However, the relation between the energy obtained with actual devices and the economic and environmental cost of their installation limits the practical application of these solutions. In order to optimize the design of this technology and achieve its successful installation and use, a detailed knowledge about the energy potential of tides at the specific location is necessary. This calculation is not easy and requires the use of specialized software tools. Currently, there is no specific software to evaluate the tidal currents energy potential, but there are more than a few codes able to calculate the hydraulic flow in rivers, estuaries and coastal regions. These programs are usually used for the calculation of pollut...