Search results

[EN] The need to increase measurement accuracy of fuel consumption and pollutant emissions in vehicles is forcing the market to develop chassis-dyno test cells that reproduce on-road conditions realistically. Air-cooling is key to vehicle performance. It is therefore critical that the design of a test cell guarantees realistic cooling of all vehicle components, as important errors in fuel consumption and emissions measurements may otherwise arise. In a test-room, a blower placed in front of the vehicle supplies the cooling air. While there are some guidelines in the literature for the selection of fans required for emissions measurements for standard driving cycles, the information for designing the air supply system for specific tests in other areas is scarce. New Real Driving Emissions (RDE) legislation will force manufacturers to perform onroad measurements of pollutants. This represents a significant challenge due to the variability of conditions coming from non-controlled parameters. In order to optimize vehicles, different tests are performed in cells equipped with a chassis-dyno where the on-road flow field around the vehicle is reproduced as closely as possible. This work provides some guidelines for the definition of the airflow supply system of chassis-dyno facilities for vehicle optimization tests, based on a CFD analysis of the flow characteristics around the vehicle. By comparison with the solution obtained for a vehicle in real road driving conditions, the exit section of the blower and the distance between the blower exit and the car that best reproduce realistic on-road flow conditions in a test room are determined. 2017 Elsevier Ltd. All rights reserved. ; Broatch, A.; Margot, X.; Gil, A.; Galindo, E.; Soler, R. (2017). Definition of wind blowers for vehicles testing at chassis-dyno facilities using a CFD approach. Transportation Research Part D Transport and Environment. 55:99-112. doi:10.1016/j.trd.2017.06.029 ; S ; 99 ; 112 ; 55

[EN] The ability to handle complex geometries is an important part of transient calculations; therefore, the need for fully automatic mesh generation capable of dealing with such geometries is quite demanded. In this paper a specific approach to fully automatic three-dimensional mesh generation is presented. An approach to moving the generated mesh is also outlined. In particular, the simulation of a diesel injector needle movement is sought. The movement of the needle was calculated on the basis of injection rate experimental data and injection rate predicted data with steady state boundaries and geometry. The simulation was performed using the commercial code STAR-CD version 4.06. (C) 2010 Elsevier Ltd. All rights reserved. ; This research was funded by the Spanish Government in the framework of the Project "Caracterizacion experimental de la cavitacion en el flujo interno e influencia sobre modelos de chorro Diesel'', Reference TRA2007-68006-C02-01. SH and PF were partially supported by the Universidad Politecnica de Valencia under the program "Primeros Proyectos de investigacion'', in the framework of the project "Simulacion CFD de chorros Diesel en inyeccion directa: la atomizacion primaria'', Reference PAID-2759. ; Margot, X.; Hoyas, S.; Fajardo, P.; Patouna, S. (2010). A moving mesh generation strategy for solving an injector internal flow problem. Mathematical and Computer Modelling. 52:1143-1150. https://doi.org/10.1016/j.mcm.2010.03.018 ; S ; 1143 ; 1150 ; 52

1143 1150 52 ; S ; [EN] The ability to handle complex geometries is an important part of transient calculations; therefore, the need for fully automatic mesh generation capable of dealing with such geometries is quite demanded. In this paper a specific approach to fully automatic three-dimensional mesh generation is presented. An approach to moving the generated mesh is also outlined. In particular, the simulation of a diesel injector needle movement is sought. The movement of the needle was calculated on the basis of injection rate experimental data and injection rate predicted data with steady state boundaries and geometry. The simulation was performed using the commercial code STAR-CD version 4.06. (C) 2010 Elsevier Ltd. All rights reserved. This research was funded by the Spanish Government in the framework of the Project "Caracterizacion experimental de la cavitacion en el flujo interno e influencia sobre modelos de chorro Diesel'', Reference TRA2007-68006-C02-01. SH and PF were partially supported by the Universidad Politecnica de Valencia under the program "Primeros Proyectos de investigacion'', in the framework of the project "Simulacion CFD de chorros Diesel en inyeccion directa: la atomizacion primaria'', Reference PAID-2759. Margot, X.; Hoyas, S.; Fajardo, P.; Patouna, S. (2010). A moving mesh generation strategy for solving an injector internal flow problem. Mathematical and Computer Modelling. 52:1143-1150. doi:10.1016/j.mcm.2010.03.018

This is the author's version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087420921584. ; [EN] This article presents a study of the impact on engine efficiency of the heat loss reduction due to in-cylinder coating insulation. A numerical methodology based on one-dimensional heat transfer model is developed. Since there is no analytic solution for engines, the one-dimensional model was validated with the results of a simple "equivalent" problem, and then applied to different engine boundary conditions. Later on, the analysis of the effect of different coating properties on the heat transfer using the simplified one-dimensional heat transfer model is performed. After that, the model is coupled with a complete virtual engine that includes both thermodynamic and thermal modeling. Next, the thermal flows across the cylinder parts coated with the insulation material (piston and cylinder head) are predicted and the effect of the coating on engine indicated efficiency is analyzed in detail. The results show the gain limits, in terms of engine efficiency, that may be obtained with advanced coating solutions. ; The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The equipment used in this work has been partially supported by FEDER project funds "otacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT)'' (Grant No. FEDER-ICTS-2012-06), framed in the operational program of unique scientific and technical infrastructure of the Spanish Government. This project has received ...

[EN] The stringent environmental constraints have led the industry to look for new technologies that improve the design of internal combustion engines (ICE), mainly focused on achieving higher thermal efficiency and reducing pollutant emissions. Numerical simulations play a key role for optimizing engine design, but modelling the physical processes such as the combustion and the heat transfer to the walls, represents a challenge due to the complexity of the phenomena involved. Combustion has to be modeled properly, and heat transfer models from gas to wall require coupling with solid wall models (CHT Conjugate Heat Transfer calculations). In this paper, a new approach is presented, focused on optimizing the computing time needed to perform CHT simulations. It is based on the use of the Rate of Heat Release (RoHR) obtained from a CFD calculation to replace the combustion process. The study is performed for a spark ignition (SI) engine. The proposed approach is validated for the heat transfer to the piston wall. The study shows that the CHT-RoHR approach yields very good results in terms of spatially averaged values during the whole engine cycle and allows considerable reduction in computational cost. It is therefore very useful to perform parametric studies. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 724084. ; Broatch, A.; Olmeda, P.; Margot, X.; Escalona-Cornejo, JE. (2019). New approach to study the heat transfer in internal combustion engines by 3D modelling. International Journal of Thermal Sciences. 138:405-415. https://doi.org/10.1016/j.ijthermalsci.2019.01.006 ; S ; 405 ; 415 ; 138

[EN] This paper reports the results of an experimental campaign where four different inlet geometries for the compressor of an automotive turbocharger were acoustically characterized. These four geometries (a straight pipe for reference, a tapered duct, a 90º elbow and a reservoir) were selected for their potential for deep surge margin enhancement, while being simple enough to be commonly found in production vehicles. A detailed measurement of this surge margin enhancement was performed, together with acoustic measurements of both radiated and orifice noise at design conditions of best isentropic efficiency and also close to the deep surge limit. Results demonstrated that while all the proposed geometries indeed enlarged the usable air mass flow range, changes in the acoustic behaviour of the system could be positive, neutral, or even negative. It is therefore important to carefully consider accurate noise measurements before implementing these geometric solutions in production vehicles, and to further pursue research on the link between the characteristic flow pattern produced by each inlet geometry and the noise emission of the turbocompressor. ; The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The equipment used in this work has been partially supported by FEDER project funds ''Dotacio´n de infraestructuras cientı´fico te´cnicas para el Centro Integral de Mejora Energe´tica y Medioambiental de Sistemas de Transporte (CiMeT)'' (grant number FEDER-ICTS-2012-06), framed in the operational program of unique scientific and technical infrastructure of the Spanish Government. ; Broatch, A.; Margot, X.; Garcia Tiscar, J.; Roig-Villanueva, F. (2018). Impact of simple surge-enhancing inlet geometries on the acoustic behaviour of a turbocompressor. International Journal of Engine Research. https://doi.org/10.1177/1468087418784125 ; S

[EN] To comply with the very strict emissions regulation the automotive industry is succeeding in developing ever more efficient engines, and there is scope for more improvements. In this regard, some investigations have suggested that insulating the combustion chamber walls of an internal combustion engine (ICE) yield low thermal losses. Most of the literature available on this topic presents simplified models that do not allow studying in detail the coating impact on engine efficiency. A more precise approach that consists in the combination of Computational Fluid Dynamics (CFD) and Conjugate Heat Transfer (CHT) simulations is used in this paper to predict the heat losses through the combustion chamber walls of a spark ignition (SI) engine. Two configurations are considered for the single cylinder engine: the metallic case and the same engine with coated piston and cylinder head. The insulation material has a low thermal conductivity (k 1.0W/(mK)). The numerical results are validated by comparison with the results of a 1D heat transfer model and with experimental data for a medium load operation point (3000 rpm -7 bar IMEP). The solutions obtained are analysed in detail in terms of wall temperature distribution and heat transfer. The impact of the coating on the engine efficiency is thus assessed. The CFD-CHT calculations yields very good results in terms of heat transfer prediction during the whole engine cycle. ; The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 724084. ; Broatch, A.; Olmeda, P.; Xandra-Marcelle, M.; Escalona-Cornejo, JE. (2021). Conjugate heat transfer study of the impact of "thermo-swing" coatings on internal combustion engines heat losses. International Journal of Engine Research. 22(9):2958-2967. https://doi.org/10.1177/1468087420960617 ; S ; 2958 ; 2967 ; 22 ; 9 ; Broatch, ...

[EN] The spray characteristics and, consequently, the success of the Diesel combustion process is strongly affected by the manner in which fuel is introduced in the combustion chamber. This work consists in studying the effect of needle motion of typical single-hole sac-type injectors on nozzle exit conditions. Three-dimensional moving mesh simulations have been carried out to calculate the injection process using cylindrical and conical nozzle geometries. The CFD analysis includes a study of the effect of cavitation on kinetic turbulent energy and velocity profiles. Results show that the flow within the nozzle and at the exit varies depending on the nozzle geometry and needle position. The model predicts clouds of cavitation that grow and exit the nozzle at low needle lifts. A kind of hysteresis in the development of the flow has also been observed between needle opening and closing. The existing correlation between turbulence and cavitation at the nozzle hole exit during the needle motion has been quantified ; This research has been funded by the Spanish Government in the frame of the Project "Caracterizacion experimental de la cavitacion en el flujo interno e influencia sobre modelos de chorro Diesel," Reference TRA2007-68006-C02-01. S.H. and P.F. were partially supported by the Universidad Politecnica de Valencia under the program "Primeros Proyectos de investigacion," in the frame of the project "Simulacion CFD de chorros Diesel en inyeccion directa: la atomizacion primaria," Reference PAID-2759 and by the Generalitat Valenciana under Contract No. GV/2010/039. ; Margot, XM.; Hoyas Calvo, S.; Fajardo, P.; Patouna, S. (2011). CFD Study of Needle Motion Influence on the Spray Conditions of Single-Hole Injectors. Atomization and Sprays. 21(1):31-40. https://doi.org/10.1615/AtomizSpr.v21.i1.30 ; S ; 31 ; 40 ; 21 ; 1