Thermal effects on the diesel injector performance through adiabatic 1D modelling. Part II: Model validation, results of the simulations and discussion

[EN] In this paper, a one-dimensional computational model of the flow in a common-rail injector is used to compute local variations of fuel temperature (including the temperature change produced upon expansion across the nozzle) and analyse their effect on injector dynamics. These variations are accounted through the adiabatic flow hypothesis, assessed in a first part of the paper where the model features are also described. They imply variations in the fuel properties and the flow regime established across the injector internal restrictions driving the solenoid valve. An extensive validation of the model against experimental results is presented for a wide range of conditions. Multiple injection strategies are also explored, analysing the influence of the inlet fuel temperature and its variations on the mass injected by successive injections and the critical dwell time below which they cannot be separated. Results show significant changes in fuel temperature across some injector restrictions. These changes are greater the higher the rail pressure and lower the fuel temperature at the injector inlet. In the case of the flow across nozzle orifices, the fuel can be either heated or subcooled depending on the operating conditions, the heating being especially relevant for cold-start-like fuel temperatures at the inlet. Thermal effects also influence the injection rate and duration. This influence on injector dynamics is particularly accused in the injector of study due to its ballistic nature. In this regard, the time needed to effectively separate two successive injections is greater the higher the fuel temperature and the injection pressure.This work was partly sponsored by FEDER and the Spanish "Ministerio de Economia y Competitividad" in the frame of the project "Desarrollo de modelos de combustion y emisiones HPC para el analisis de plantas propulsivas de transporte sostenible (CHEST)", reference TRA2017-89139-C2-1-R-AR. On the other hand, the support given to Mr Mario Belmar by "Universitat Politecnica de Valencia" through the "FPI-Subprograma 2" grant within the "Programa de Apoyo para la Investigacion y Desarrollo (PAID-01-18)" is gratefully acknowledged by the authors.Payri, R.; Salvador, FJ.; Carreres, M.; Belmar-Gil, M. (2020). Thermal effects on the diesel injector performance through adiabatic 1D modelling. Part II: Model validation, results of the simulations and discussion. Fuel. 260:1-17. https://doi.org/10.1016/j.fuel.2019.115663S117260Gumus, M., Sayin, C., & Canakci, M. (2012). The impact of fuel injection pressure on the exhaust emissions of a direct injection diesel engine fueled with biodiesel–diesel fuel blends. Fuel, 95, 486-494. doi:10.1016/j.fuel.2011.11.020Agarwal, A. K., Dhar, A., Gupta, J. G., Kim, W. I., Choi, K., Lee, C. S., & Park, S. (2015). Effect of fuel injection pressure and injection timing of Karanja biodiesel blends on fuel spray, engine performance, emissions and combustion characteristics. Energy Conversion and Management, 91, 302-314. doi:10.1016/j.enconman.2014.12.004Zecca, A., & Chiari, L. (2010). Fossil-fuel constraints on global warming. Energy Policy, 38(1), 1-3. doi:10.1016/j.enpol.2009.06.068Wang, J., Feng, L., Tang, X., Bentley, Y., & Höök, M. (2017). The implications of fossil fuel supply constraints on climate change projections: A supply-side analysis. Futures, 86, 58-72. doi:10.1016/j.futures.2016.04.007Wang, X., Huang, Z., Zhang, W., Kuti, O. A., & Nishida, K. (2011). Effects of ultra-high injection pressure and micro-hole nozzle on flame structure and soot formation of impinging diesel spray. Applied Energy, 88(5), 1620-1628. doi:10.1016/j.apenergy.2010.11.035Boccardo, G., Millo, F., Piano, A., Arnone, L., Manelli, S., Fagg, S., … Weber, J. (2019). Experimental investigation on a 3000 bar fuel injection system for a SCR-free non-road diesel engine. Fuel, 243, 342-351. doi:10.1016/j.fuel.2019.01.122Mancaruso, E., Sequino, L., & Vaglieco, B. M. (2016). Analysis of the pilot injection running Common Rail strategies in a research diesel engine by means of infrared diagnostics and 1d model. Fuel, 178, 188-201. doi:10.1016/j.fuel.2016.03.066Breda, S., D’Orrico, F., Berni, F., d’ Adamo, A., Fontanesi, S., Irimescu, A., & Merola, S. S. (2019). Experimental and numerical study on the adoption of split injection strategies to improve air-butanol mixture formation in a DISI optical engine. Fuel, 243, 104-124. doi:10.1016/j.fuel.2019.01.111Wang, B., Pamminger, M., Vojtech, R., & Wallner, T. (2018). Impact of injection strategies on combustion characteristics, efficiency and emissions of gasoline compression ignition operation in a heavy-duty multi-cylinder engine. International Journal of Engine Research, 21(8), 1426-1440. doi:10.1177/1468087418801660Sun, Z.-Y., Li, G.-X., Chen, C., Yu, Y.-S., & Gao, G.-X. (2015). Numerical investigation on effects of nozzle’s geometric parameters on the flow and the cavitation characteristics within injector’s nozzle for a high-pressure common-rail DI diesel engine. Energy Conversion and Management, 89, 843-861. doi:10.1016/j.enconman.2014.10.047Torelli, R., Som, S., Pei, Y., Zhang, Y., & Traver, M. (2017). Influence of fuel properties on internal nozzle flow development in a multi-hole diesel injector. Fuel, 204, 171-184. doi:10.1016/j.fuel.2017.04.123Salvador, F., De la Morena, J., Crialesi-Esposito, M., & Martínez-López, J. (2017). Comparative study of the internal flow in diesel injection nozzles at cavitating conditions at different needle lifts with steady and transient simulations approaches. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 232(8), 1060-1078. doi:10.1177/0954407017725672Ihme, M., Ma, P. C., & Bravo, L. (2018). Large eddy simulations of diesel-fuel injection and auto-ignition at transcritical conditions. International Journal of Engine Research, 20(1), 58-68. doi:10.1177/1468087418819546Desantes, J. M., Salvador, F. J., Carreres, M., & Martínez-López, J. (2014). Large-eddy simulation analysis of the influence of the needle lift on the cavitation in diesel injector nozzles. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 229(4), 407-423. doi:10.1177/0954407014542627Payri, R., Salvador, F. J., Carreres, M., & De la Morena, J. (2016). Fuel temperature influence on the performance of a last generation common-rail diesel ballistic injector. Part II: 1D model development, validation and analysis. Energy Conversion and Management, 114, 376-391. doi:10.1016/j.enconman.2016.02.043Salvador, F. J., Carreres, M., Crialesi-Esposito, M., & Plazas, A. H. (2017). Determination of critical operating and geometrical parameters in diesel injectors through one dimensional modelling, design of experiments and an analysis of variance. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 232(13), 1762-1781. doi:10.1177/0954407017735262Desantes, J., Salvador, F., Carreres, M., & Jaramillo, D. (2015). Experimental Characterization of the Thermodynamic Properties of Diesel Fuels Over a Wide Range of Pressures and Temperatures. SAE International Journal of Fuels and Lubricants, 8(1), 190-199. doi:10.4271/2015-01-0951Dernotte, J., Hespel, C., Houille, S., Foucher, F., & Mounaim-Rousselle, C. (2012). INFLUENCE OF FUEL PROPERTIES ON THE DIESEL INJECTION PROCESS IN NONVAPORIZING CONDITIONS. Atomization and Sprays, 22(6), 461-492. doi:10.1615/atomizspr.2012004401Park, Y., Hwang, J., Bae, C., Kim, K., Lee, J., & Pyo, S. (2015). Effects of diesel fuel temperature on fuel flow and spray characteristics. Fuel, 162, 1-7. doi:10.1016/j.fuel.2015.09.008Wang, Z., Ding, H., Wyszynski, M. L., Tian, J., & Xu, H. (2015). Experimental study on diesel fuel injection characteristics under cold start conditions with single and split injection strategies. Fuel Processing Technology, 131, 213-222. doi:10.1016/j.fuproc.2014.10.003Salvador, F. J., Gimeno, J., Carreres, M., & Crialesi-Esposito, M. (2017). Experimental assessment of the fuel heating and the validity of the assumption of adiabatic flow through the internal orifices of a diesel injector. Fuel, 188, 442-451. doi:10.1016/j.fuel.2016.10.061Nurick, W. H. (1976). Orifice Cavitation and Its Effect on Spray Mixing. Journal of Fluids Engineering, 98(4), 681-687. doi:10.1115/1.3448452Soteriou C, Andrews R, Smith M. Direct injection diesel sprays and the effect of cavitation and hydraulic flip on atomization. SAE Pap 950080 1995. doi: 10.4271/950080.Lichtarowicz, A., Duggins, R. K., & Markland, E. (1965). Discharge Coefficients for Incompressible Non-Cavitating Flow through Long Orifices. Journal of Mechanical Engineering Science, 7(2), 210-219. doi:10.1243/jmes_jour_1965_007_029_02Franc J-P. The Rayleigh-Plesset equation: a simple and powerful tool to understand various aspects of cavitation. Fluid Dyn. Cavitation Cavitating Turbopumps, vol. 496, Vienna: Springer; 2007, p. 1–41. doi: 10.1007/978-3-211-76669-9_1.PAYRI, R., GARCIA, J., SALVADOR, F., & GIMENO, J. (2005). Using spray momentum flux measurements to understand the influence of diesel nozzle geometry on spray characteristics. Fuel, 84(5), 551-561. doi:10.1016/j.fuel.2004.10.009Salvador, F. J., Gimeno, J., Carreres, M., & Crialesi-Esposito, M. (2016). Fuel temperature influence on the performance of a last generation common-rail diesel ballistic injector. Part I: Experimental mass flow rate measurements and discussion. Energy Conversion and Management, 114, 364-375. doi:10.1016/j.enconman.2016.02.042Payri, R., Salvador, F. J., Gimeno, J., & Bracho, G. (2008). A NEW METHODOLOGY FOR CORRECTING THE SIGNAL CUMULATIVE PHENOMENON ON INJECTION RATE MEASUREMENTS. Experimental Techniques, 32(1), 46-49. doi:10.1111/j.1747-1567.2007.00188.xTheodorakakos, A., Strotos, G., Mitroglou, N., Atkin, C., & Gavaises, M. (2014). Friction-induced heating in nozzle hole micro-channels under extreme fuel pressurisation. Fuel, 123, 143-150. doi:10.1016/j.fuel.2014.01.050Strotos, G., Koukouvinis, P., Theodorakakos, A., Gavaises, M., & Bergeles, G. (2015). Transient heating effects in high pressure Diesel injector nozzles. International Journal of Heat and Fluid Flow, 51, 257-267. doi:10.1016/j.ijheatfluidflow.2014.10.010Salvador, F. J., Carreres, M., De la Morena, J., & Martínez-Miracle, E. (2018). Computational assessment of temperature variations through calibrated orifices subjected to high pressure drops: Application to diesel injection nozzles. Energy Conversion and Management, 171, 438-451. doi:10.1016/j.enconman.2018.05.102Payri, R., Salvador, F. J., Gimeno, J., & Bracho, G. (2008). Effect of fuel properties on diesel spray development in extreme cold conditions. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 222(9), 1743-1753. doi:10.1243/09544070jauto844Salvador, F. J., Gimeno, J., De la Morena, J., & Carreres, M. (2012). Using one-dimensional modeling to analyze the influence of the use of biodiesels on the dynamic behavior of solenoid-operated injectors in common rail systems: Results of the simulations and discussion. Energy Conversion and Management, 54(1), 122-132. doi:10.1016/j.enconman.2011.10.007Moon, S., Gao, Y., Park, S., Wang, J., Kurimoto, N., & Nishijima, Y. (2015). Effect of the number and position of nozzle holes on in- and near-nozzle dynamic characteristics of diesel injection. Fuel, 150, 112-122. doi:10.1016/j.fuel.2015.01.09

Fuel temperature influence on the performance of a last generation common-rail diesel ballistic injector. Part I: Experimental mass flow rate measurements and discussion

An experimental study is conducted in this paper in order to assess the influence of the fuel temperature on the performance of a last generation common-rail ballistic solenoid injector. Mass flow rate measurements are performed for a wide range of temperatures, extending from 253 to 373 K, representative of all the possible operating conditions of the injector in a real diesel engine, including cold start. The high pressure line and the injector holder were refrigerated, making it possible to carefully control the fuel temperature, whereas measurements at cold conditions were carried out with the help of a climatic chamber. Relevant features such as stationary mass flow, injection delay or the behaviour at the opening and closing stages are analysed together with parameters governing the flow, such as the injector discharge coefficient. Results show an important influence of the fuel temperature, especially at low injection pressure. A low injection temperature results in a lower stationary mass flow rate, whereas injection duration is also reduced. These results will be explained mainly through the fuel properties variation induced by temperature, together with the ballistic nature of the injector used for the study. A second part of the paper introduces a one-dimensional model that makes it possible to reproduce these results and further explain them through the analysis of other relevant variables, such as the needle lift.This work was partly sponsored by "Ministerio de Economia y Competitividad" (Spain) in the frame of the project "Comprension de la influencia de combustibles no convencionales en el proceso de inyeccion y combustion tipo diesel", reference TRA2012-36932. The equipment used in this work has been partially supported by FEDER project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)", in the frame of the operation program of unique scientific and technical infrastructure of the Ministry of Science and Innovation of Spain. This support is gratefully acknowledged by the authors.Salvador Rubio, FJ.; Gimeno, J.; Carreres Talens, M.; Crialesi Esposito, M. (2016). Fuel temperature influence on the performance of a last generation common-rail diesel ballistic injector. Part I: Experimental mass flow rate measurements and discussion. Energy Conversion and Management. 114:364-375. doi:10.1016/j.enconman.2016.02.042S36437511

Determination of critical operating and geometrical parameters in diesel injectors through one dimensional modelling, design of experiments and an analysis of variance

[EN] In this paper, a design of experiments and a statistical analysis of variance (ANOVA) are performed to determine the parameters that have more influence on the mass flow rate profile in diesel injectors. The study has been carried out using a one dimensional model previously implemented by the authors. The investigation is split into two different parts. First, the analysis is focused on functional parameters such as the injection and discharge pressures, the energizing time and the fuel temperature. In the second part, the influence of 37 geometrical parameters such as the diameters of hydraulic lines, calibrated orifices and internal volumes, among others, are analysed. The objective of the study is to quantify the impact of small variations in the nominal value of these parameters on the injection rate profile for a given injector operating condition. In the case of the functional parameters, these small variations may be attributed to possible undesired fluctuations in the conditions that the injector is submitted to. As far as the geometrical and flow parameters are concerned, the small variations studied are representative of manufacturing tolerances that could influence the injected mass flow rate. As a result, it has been noticed that the configuration of the inlet and outlet orifices of the control volume together with the discharge coefficient of the inlet orifice, among a few others, play a remarkable role in the injector performance. The reason resides in the fact that they are in charge of controlling the behaviour of the pressure in the control volume, which importantly influences injector dynamics and therefore the injection process. Variations of only 5% in the diameter of these orifices strongly modify the shape of the rate of injection curve, influencing both the injection delay and the duration of the injection process, consequently changing the total mass delivered.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research has been partially funded by FEDER and the Spanish ‘‘Ministerio de Economı´a y Competitividad’’ through the project TRA2015-67679- c2-1-R.Salvador, FJ.; Carreres, M.; Crialesi Esposito, M.; Plazas Torres, AH. (2018). Determination of critical operating and geometrical parameters in diesel injectors through one dimensional modelling, design of experiments and an analysis of variance. Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering. 232(13):1762-1781. https://doi.org/10.1177/0954407017735262S176217812321

Fuel temperature influence on the performance of a last generation common-rail diesel ballistic injector. Part II: 1D model development, validation and analysis

A one-dimensional model of a solenoid-driven common-rail diesel injector has been developed in order to study the influence of fuel temperature on the injection process. The model has been implemented after a thorough characterization of the injector, both from the dimensional and the hydraulic point of view. In this sense, experimental tools for the determination of the geometry of the injector lines and orifices have been described in the paper, together with the hydraulic setup introduced to characterize the flow behaviour through the calibrated orifices. An extensive validation of the model has been performed by comparing the modelled mass flow rate against the experimental results introduced in the first part of the paper, which were performed for different engine-like operating conditions involving a wide range of fuel temperatures, injection pressures and energizing times. In that first part of the study, an important influence of the fuel temperature was reported, especially in terms of the dynamic behaviour of the injector, due to its ballistic nature. The results from the model have allowed to explain and further extend the findings of the experimental study by analyzing key features of the injector dynamics, such as the pressure drop established in the control volume due to the control orifices performance or the forces due to viscous friction, also assessing their influence on the needle lift laws.This work was partly sponsored by "Ministerio de Economia y Competitividad" (Spain) in the frame of the project "Comprension de la influencia de combustibles no convencionales en el proceso de inyeccion y combustion tipo diesel", reference TRA2012-36932. The equipment used in this work has been partially supported by FEDER (Spain) project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)", in the frame of the operation program of unique scientific and technical infrastructure of the Ministry of Science and Innovation of Spain. This support is gratefully acknowledged by the authors.Payri, R.; Salvador Rubio, FJ.; Carreres Talens, M.; De La Morena, J. (2016). Fuel temperature influence on the performance of a last generation common-rail diesel ballistic injector. Part II: 1D model development, validation and analysis. Energy Conversion and Management. 114:376-391. doi:10.1016/j.enconman.2016.02.043S37639111

Analysis of vortex core generation in pipe flows under different reynolds number conditions

[EN] Pipe flow is a well-documented case widely studied in both theoretical and practical applications. The present work aims at studying the influence of the Reynolds number on turbulent vortex distribution using Large Eddy Simulations (LES). Features such as the mean velocity profiles and root mean squared velocity are first numerically investigated for different fluid properties involving Reynolds numbers ranging from 5,925 to 15,190 in order to verify the law-of-the-wall and turbulence statistics with experimental and DNS data. Once the simulations are validated, the vortex core generation within the flow is studied through a detection algorithm based on the lambda 2 criterion with two different approaches, first using an absolute threshold value and then using a relative threshold value depending on the turbulent intensity. Results are compared in terms of number of structures and Probability Density Functions for both the size and the radial distributions. Finally, results are compared for one condition with the Q-criterion to assess the results obtained resulting in practically identical volume and radial distributions. These results are deemed to shed light on the vortex formation and location to generate proper inflow boundary conditions to highly resolved simulations in varied engineering applications.This research has been funded by the Spanish Ministerio de Economia y Competitividad through the project RTI2018099706-B-100: "Estudio de la atomizacion primaria mediante simulaciones DNS y tecnicas opticas de muy alta resolucion" and the Spanish Ministerio de Ciencia e innovacion through the project EQC2018004605-P: "Estudio del proceso de inyeccion en atmosferas presurizadas". The authors thankfully acknowledge the computer resources from the Rigel cluster at UPV (Spain) and the Bebop cluster from the Laboratory Computing Resource Center at Argonne National Laboratory (USA). L.A. Gonzalez-Montero is partially supported through the contract FPI -Subprograma 2 of the Universitat Politecnica de Valencia.Salvador, FJ.; Carreres, M.; Quintero-Igeño, P.; González-Montero, LA. (2021). Analysis of vortex core generation in pipe flows under different reynolds number conditions. Journal of the Brazilian Society of Mechanical Sciences and Engineering. 43(6):1-13. https://doi.org/10.1007/s40430-021-03007-311343

Large-eddy simulation analysis of the influence of the needle lift on the cavitation in diesel injector nozzles

The cavitation phenomenon has a strong influence on the internal flow and spray development in diesel injector nozzles. Despite its importance, there are many aspects which still remain unclear, especially for partial needle lifts when the injector is in the opening and closing phases. For that reason, the current paper is focused on the influence of the needle lift on the internal flow in a diesel nozzle. This study was carried out with three-dimensional simulations at a high injection pressure (160 MPa) using a homogeneous equilibrium model implemented in OpenFOAM to model the cavitation phenomenon. The nozzle was simulated with large-eddy simulation methods at six different needle lifts (10 mm, 30 mm, 50 mm, 75 mm, 100 mm and 250 mm), providing relevant information about the evolution of the internal flow, the turbulence development (the vorticity, the turbulence–cavitation interaction and the turbulent structures) and the flow characteristics in the nozzle outlet (the mass flow, the momentum flux and the effective velocity) with the needle position.Desantes Fernández, JM.; Salvador Rubio, FJ.; Carreres Talens, M.; Martínez López, J. (2015). Large-eddy simulation analysis of the influence of the needle lift on the cavitation in diesel injector nozzles. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 229(4):407-423. doi:10.1177/0954407014542627S4074232294Faeth, G. ., Hsiang, L.-P., & Wu, P.-K. (1995). Structure and breakup properties of sprays. International Journal of Multiphase Flow, 21, 99-127. doi:10.1016/0301-9322(95)00059-7Park, S. H., Suh, H. K., & Lee, C. S. (2009). Effect of Bioethanol−Biodiesel Blending Ratio on Fuel Spray Behavior and Atomization Characteristics. Energy & Fuels, 23(8), 4092-4098. doi:10.1021/ef900068aPAYRI, R., GARCIA, J., SALVADOR, F., & GIMENO, J. (2005). Using spray momentum flux measurements to understand the influence of diesel nozzle geometry on spray characteristics. Fuel, 84(5), 551-561. doi:10.1016/j.fuel.2004.10.009Suh, H. K., & Lee, C. S. (2008). Effect of cavitation in nozzle orifice on the diesel fuel atomization characteristics. International Journal of Heat and Fluid Flow, 29(4), 1001-1009. doi:10.1016/j.ijheatfluidflow.2008.03.014Payri, R., Salvador, F. J., Gimeno, J., & de la Morena, J. (2009). Effects of nozzle geometry on direct injection diesel engine combustion process. Applied Thermal Engineering, 29(10), 2051-2060. doi:10.1016/j.applthermaleng.2008.10.009Park, S. H., Kim, S. H., & Lee, C. S. (2009). Mixing Stability and Spray Behavior Characteristics of Diesel−Ethanol−Methyl Ester Blended Fuels in a Common-Rail Diesel Injection System. Energy & Fuels, 23(10), 5228-5235. doi:10.1021/ef9004847Desantes, J. M., Payri, R., Salvador, F. J., & Gil, A. (2006). Development and validation of a theoretical model for diesel spray penetration. Fuel, 85(7-8), 910-917. doi:10.1016/j.fuel.2005.10.023Desantes, J. M., Payri, R., Garcia, J. M., & Salvador, F. J. (2007). A contribution to the understanding of isothermal diesel spray dynamics. Fuel, 86(7-8), 1093-1101. doi:10.1016/j.fuel.2006.10.011Badock, C., Wirth, R., Fath, A., & Leipertz, A. (1999). Investigation of cavitation in real size diesel injection nozzles. International Journal of Heat and Fluid Flow, 20(5), 538-544. doi:10.1016/s0142-727x(99)00043-0Som, S., Aggarwal, S. K., El-Hannouny, E. M., & Longman, D. E. (2010). Investigation of Nozzle Flow and Cavitation Characteristics in a Diesel Injector. Journal of Engineering for Gas Turbines and Power, 132(4). doi:10.1115/1.3203146Macian, V., Payri, R., Margot, X., & Salvador, F. J. (2003). A CFD ANALYSIS OF THE INFLUENCE OF DIESEL NOZZLE GEOMETRY ON THE INCEPTION OF CAVITATION. Atomization and Sprays, 13(5-6), 579-604. doi:10.1615/atomizspr.v13.i56.80Alajbegovic, A., Meister, G., Greif, D., & Basara, B. (2002). Three phase cavitating flows in high-pressure swirl injectors. Experimental Thermal and Fluid Science, 26(6-7), 677-681. doi:10.1016/s0894-1777(02)00179-6Unverdi, S. O., & Tryggvason, G. (1992). A front-tracking method for viscous, incompressible, multi-fluid flows. Journal of Computational Physics, 100(1), 25-37. doi:10.1016/0021-9991(92)90307-kBrackbill, J. ., Kothe, D. ., & Zemach, C. (1992). A continuum method for modeling surface tension. Journal of Computational Physics, 100(2), 335-354. doi:10.1016/0021-9991(92)90240-yPlesset M, Devine R. Effect of exposure time on cavitation damage. Report (Office of Naval Research Contract Nonr-220(28)), California Institute of Technology, Pasadena, California, USA, 1965.Chen, Y., & Heister, S. D. (1996). MODELING CAVITATING FLOWS IN DIESEL INJECTORS. Atomization and Sprays, 6(6), 709-726. doi:10.1615/atomizspr.v6.i6.50Vortmann, C., Schnerr, G. H., & Seelecke, S. (2003). Thermodynamic modeling and simulation of cavitating nozzle flow. International Journal of Heat and Fluid Flow, 24(5), 774-783. doi:10.1016/s0142-727x(03)00003-1Echouchene, F., Belmabrouk, H., Le Penven, L., & Buffat, M. (2011). Numerical simulation of wall roughness effects in cavitating flow. International Journal of Heat and Fluid Flow, 32(5), 1068-1075. doi:10.1016/j.ijheatfluidflow.2011.05.010Salvador, F. J., Romero, J.-V., Roselló, M.-D., & Martínez-López, J. (2010). Validation of a code for modeling cavitation phenomena in Diesel injector nozzles. Mathematical and Computer Modelling, 52(7-8), 1123-1132. doi:10.1016/j.mcm.2010.02.027Salvador, F. J., Hoyas, S., Novella, R., & Martínez-López, J. (2011). Numerical simulation and extended validation of two-phase compressible flow in diesel injector nozzles. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 225(4), 545-563. doi:10.1177/09544070jauto1569Payri, F., Payri, R., Salvador, F. J., & Martínez-López, J. (2012). A contribution to the understanding of cavitation effects in Diesel injector nozzles through a combined experimental and computational investigation. Computers & Fluids, 58, 88-101. doi:10.1016/j.compfluid.2012.01.005Salvador, F. J., Martínez-López, J., Caballer, M., & De Alfonso, C. (2013). Study of the influence of the needle lift on the internal flow and cavitation phenomenon in diesel injector nozzles by CFD using RANS methods. Energy Conversion and Management, 66, 246-256. doi:10.1016/j.enconman.2012.10.011Salvador, F. J., Martínez-López, J., Romero, J.-V., & Roselló, M.-D. (2013). Computational study of the cavitation phenomenon and its interaction with the turbulence developed in diesel injector nozzles by Large Eddy Simulation (LES). Mathematical and Computer Modelling, 57(7-8), 1656-1662. doi:10.1016/j.mcm.2011.10.050Piomelli, U. (1999). Large-eddy simulation: achievements and challenges. Progress in Aerospace Sciences, 35(4), 335-362. doi:10.1016/s0376-0421(98)00014-1Launder, B. E., & Spalding, D. B. (1974). The numerical computation of turbulent flows. Computer Methods in Applied Mechanics and Engineering, 3(2), 269-289. doi:10.1016/0045-7825(74)90029-2Payri, F., Bermúdez, V., Payri, R., & Salvador, F. J. (2004). The influence of cavitation on the internal flow and the spray characteristics in diesel injection nozzles. Fuel, 83(4-5), 419-431. doi:10.1016/j.fuel.2003.09.010Payri, R., Salvador, F. J., Gimeno, J., & de la Morena, J. (2009). Study of cavitation phenomena based on a technique for visualizing bubbles in a liquid pressurized chamber. International Journal of Heat and Fluid Flow, 30(4), 768-777. doi:10.1016/j.ijheatfluidflow.2009.03.011Martínez López, J. (s. f.). Estudio computacional de la influencia del levantamiento de aguja sobre el flujo interno y el fenómeno de la cavitación en toberas de inyección diésel. doi:10.4995/thesis/10251/29291Tabor, G. R., & Baba-Ahmadi, M. H. (2010). Inlet conditions for large eddy simulation: A review. Computers & Fluids, 39(4), 553-567. doi:10.1016/j.compfluid.2009.10.007Payri, R., Gimeno, J., Marti-Aldaravi, P., & Bracho, G. (2013). Study of the influence of the inlet boundary conditions in a LES simulation of internal flow in a diesel injector. Mathematical and Computer Modelling, 57(7-8), 1709-1715. doi:10.1016/j.mcm.2011.11.019de Villiers E. The potential of large eddy simulation for the modeling of wall bounded flows. PhD Thesis, Imperial College of Science, Technology and Medicine, London, UK, 2006.Lee, J. W., Min, K. D., Kang, K. Y., Bae, C. S., Giannadakis, E., Gavaises, M., & Arcoumanis, C. (2006). Effect of piezo-driven and solenoid-driven needle opening of common-rail diesel injectors on internal nozzle flow and spray development. International Journal of Engine Research, 7(6), 489-502. doi:10.1243/14680874jer00806Desantes, J. M., Payri, R., Salvador, F. J., & De la Morena, J. (2010). Influence of cavitation phenomenon on primary break-up and spray behavior at stationary conditions. Fuel, 89(10), 3033-3041. doi:10.1016/j.fuel.2010.06.004Lesieur, M., Métais, O., & Comte, P. (2005). Large-Eddy Simulations of Turbulence. doi:10.1017/cbo9780511755507Sagaut, P. (2001). Large Eddy Simulation for Incompressible Flows. Scientific Computation. doi:10.1007/978-3-662-04416-

Experimental Characterization of the Thermodynamic Properties of Diesel Fuels Over a Wide Range of Pressures and Temperatures

The influence of pressure and temperature on some of the important thermodynamic properties of diesel fuels has been assessed for a set of fuels. The study focuses on the experimental determination of the speed of sound, density and compressibility (via the bulk modulus) of these fuels by means of a method that is thoroughly described in this paper. The setup makes use of a common-rail injection system in order to transmit a pressure wave through a high-pressure line and measure the time it takes for the wave to travel a given distance. Measurements have been performed in a wide range of pressures (from atmospheric pressure up to 200 MPa) and temperatures (from 303 to 353 K), in order to generate a fuel properties database for modelers on the field of injection systems for diesel engines to incorporate to their simulations.This work was partly sponsored by "Ministerio de Economia y Competitividad" (Spanish Ministry of Economy) in the frame of the project "Comprension de la influencia de combustibles no convencionales en el proceso de inyeccion y combustion tipo diesel", reference TRA2012-36932. The equipment used in this work hasDesantes Fernández, JM.; Salvador Rubio, FJ.; Carreres Talens, M.; Jaramillo-Císcar, D. (2015). Experimental Characterization of the Thermodynamic Properties of Diesel Fuels Over a Wide Range of Pressures and Temperatures. SAE International Journal of Fuel and Lubricants. 8(1):190-199. https://doi.org/10.4271/2015-01-0951S1901998

Complete modelling of a piezo actuator last-generation injector for diesel injection systems

An experimental and computational study of an increasingly used third-generation common-rail injection system with a piezo actuator has been carried out. A complete characterization of the different elements of the system, both geometrically and hydraulically, has been performed in order to describe its behaviour. The information obtained through the characterization has been used to create a one-dimensional model that has been implemented in the commercial software AMESim and extensively validated against experimental data. The results of the validation demonstrate the model ability to predict the injection rate of the injector with a high level of accuracy, therefore, constituting a powerful tool in order to carry out further studies of this type of injection system.This work was supported by the Ministerio de Ciencia e Innovacion in the frame of the project 'Estudio teorico experimental sobre la influencia del tipo de combustible en los procesos de atomizacion y evaporacion del chorro Diesel (PROFUEL)' [grant number TRA 2011-26293]. This support is gratefully acknowledged by the authors.Salvador Rubio, FJ.; Plazas Torres, AH.; Gimeno García, J.; Carreres Talens, M. (2014). Complete modelling of a piezo actuator last-generation injector for diesel injection systems. International Journal of Engine Research. 15(1):3-19. https://doi.org/10.1177/1468087412455373S319151Payri, R., Molina, S., Salvador, F. J., & Gimeno, J. (2004). A study of the relation between nozzle geometry, internal flow and sprays characteristics in diesel fuel injection systems. KSME International Journal, 18(7), 1222-1235. doi:10.1007/bf02983297Bermúdez, V., Payri, R., Salvador, F. J., & Plazas, A. H. (2005). Study of the influence of nozzle seat type on injection rate and spray behaviour. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 219(5), 677-689. doi:10.1243/095440705x28303KENT, J. C., & BROWN, G. M. (1983). Nozzle Exit Flow Characteristics for Square-edged and Rounded Inlet Geometries. Combustion Science and Technology, 30(1-6), 121-132. doi:10.1080/00102208308923615Payri, R., Salvador, F. J., Gimeno, J., & de la Morena, J. (2009). Effects of nozzle geometry on direct injection diesel engine combustion process. Applied Thermal Engineering, 29(10), 2051-2060. doi:10.1016/j.applthermaleng.2008.10.009Payri, R., Climent, H., Salvador, F. J., & Favennec, A. G. (2004). Diesel Injection System Modelling. Methodology and Application for a First-generation Common Rail System. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 218(1), 81-91. doi:10.1243/095440704322829191Payri, R., Tormos, B., Salvador, F. J., & Plazas, A. H. (2005). Using one-dimensional modelling codes to analyse the influence of diesel nozzle geometry on injection rate characteristics. International Journal of Vehicle Design, 38(1), 58. doi:10.1504/ijvd.2005.006605Payri, R., Salvador, F. J., Martí-Aldaraví, P., & Martínez-López, J. (2012). Using one-dimensional modeling to analyse the influence of the use of biodiesels on the dynamic behavior of solenoid-operated injectors in common rail systems: Detailed injection system model. Energy Conversion and Management, 54(1), 90-99. doi:10.1016/j.enconman.2011.10.004Salvador, F. J., Gimeno, J., De la Morena, J., & Carreres, M. (2012). Using one-dimensional modeling to analyze the influence of the use of biodiesels on the dynamic behavior of solenoid-operated injectors in common rail systems: Results of the simulations and discussion. Energy Conversion and Management, 54(1), 122-132. doi:10.1016/j.enconman.2011.10.007Payri, R., Salvador, F. J., Gimeno, J., & De la Morena, J. (2011). Influence of injector technology on injection and combustion development – Part 1: Hydraulic characterization. Applied Energy, 88(4), 1068-1074. doi:10.1016/j.apenergy.2010.10.012Payri, R., Salvador, F. J., Gimeno, J., & De la Morena, J. (2011). Influence of injector technology on injection and combustion development – Part 2: Combustion analysis. Applied Energy, 88(4), 1130-1139. doi:10.1016/j.apenergy.2010.10.004Payri, R., Salvador, F. J., Gimeno, J., & Bracho, G. (2008). A NEW METHODOLOGY FOR CORRECTING THE SIGNAL CUMULATIVE PHENOMENON ON INJECTION RATE MEASUREMENTS. Experimental Techniques, 32(1), 46-49. doi:10.1111/j.1747-1567.2007.00188.xMacian, V., Bermudez, V., Payri, R., & Gimeno, J. (2003). NEW TECHNIQUE FOR DETERMINATION OF INTERNAL GEOMETRY OF A DIESEL NOZZLE WITH THE USE OF SILICONE METHODOLOGY. Experimental Techniques, 27(2), 39-43. doi:10.1111/j.1747-1567.2003.tb00107.xMacian, V., Payri, R., Margot, X., & Salvador, F. J. (2003). A CFD ANALYSIS OF THE INFLUENCE OF DIESEL NOZZLE GEOMETRY ON THE INCEPTION OF CAVITATION. Atomization and Sprays, 13(5-6), 579-604. doi:10.1615/atomizspr.v13.i56.80Payri, F., Bermúdez, V., Payri, R., & Salvador, F. J. (2004). The influence of cavitation on the internal flow and the spray characteristics in diesel injection nozzles. Fuel, 83(4-5), 419-431. doi:10.1016/j.fuel.2003.09.010Ohrn, T. R., Senser, D. W., & Lefebvre, A. H. (1991). GEOMETRICAL EFFECTS ON DISCHARGE COEFFICIENTS FOR PLAIN-ORIFICE ATOMIZERS. Atomization and Sprays, 1(2), 137-153. doi:10.1615/atomizspr.v1.i2.10Lichtarowicz, A., Duggins, R. K., & Markland, E. (1965). Discharge Coefficients for Incompressible Non-Cavitating Flow through Long Orifices. Journal of Mechanical Engineering Science, 7(2), 210-219. doi:10.1243/jmes_jour_1965_007_029_02Salvador, F. J., Romero, J.-V., Roselló, M.-D., & Martínez-López, J. (2010). Validation of a code for modeling cavitation phenomena in Diesel injector nozzles. Mathematical and Computer Modelling, 52(7-8), 1123-1132. doi:10.1016/j.mcm.2010.02.027Payri, R., Salvador, F. J., Gimeno, J., & de la Morena, J. (2009). Study of cavitation phenomena based on a technique for visualizing bubbles in a liquid pressurized chamber. International Journal of Heat and Fluid Flow, 30(4), 768-777. doi:10.1016/j.ijheatfluidflow.2009.03.01

Computational assessment of temperature variations through calibrated orifices subjected to high pressure drops: application to diesel injection nozzles

[EN] This paper conducts an investigation on the temperature variations experienced by the fuel when it expands through the calibrated orifices of a commercial diesel injector. Experimental results of the temperature change across a calibrated orifice upon expansion, extracted from a previous work, are compared to the temperature predicted by computational fluid dynamic simulations under the assumption of adiabatic flow, with no heat transfer to the surroundings. The comparison points out that the simulations are able to predict the thermal effects taking place inside the orifice. Once the model is validated, the flow morphology is analyzed to explain the trends observed in the fuel temperature change across the orifice depending on the operating conditions. Two opposed effects take place inside the orifice: on the one hand, the flow is cooled in the orifice core due to depressurization; on the other hand, the fuel is importantly heated near the walls due to viscous friction. As expected, the net effect on the outlet temperature mainly depends on the orifice discharge coefficient, governed by the orifice geometry and the flow regime (Reynolds number) induced by the injection conditions. Next, the analysis is extended to a diesel nozzle, considering that the higher pressure drops achieved in it are expected to induce even more important thermal effects. The two opposed effects also take place inside the orifice. Even though their net effect is similar, the separate effect of each phenomenon is greater, leading to differences that could be relevant for the atomization and spray formation processes. Additionally, the flow pattern shows a non-uniform distribution of the flow inside the nozzle influencing the results from the thermal point of view.Salvador, FJ.; Carreres, M.; De La Morena, J.; Martínez-Miracle-Muñoz, EC. (2018). Computational assessment of temperature variations through calibrated orifices subjected to high pressure drops: application to diesel injection nozzles. Energy Conversion and Management. 171:438-451. https://doi.org/10.1016/j.enconman.2018.05.102S43845117

Towards the semantic enrichment of Computer Interpretable Guidelines: a method for the identification of relevant ontological terms

Ponència presentada a 2018 The American Medical Informatics Association Annual Symposium (AMIA 2018) celebrat a San Francisco, Estats Units de l'Amèrica del Nord, el 3 de novembre de 2018Clinical Practice Guidelines (CPGs) contain recommendations intended to optimize patient care, produced based on a systematic review of evidence. In turn, Computer-Interpretable Guidelines (CIGs) are formalized versions of CPGs for use as decision-support systems. We consider the enrichment of the CIG by means of an OWL ontology that describes the clinical domain of the CIG, which could be exploited e.g. for the interoperability with the Electronic Health Record (EHR). As a first step, in this paper we describe a method to support the development of such an ontology starting from a CIG. The method uses an alignment algorithm for the automated identification of ontological terms relevant to the clinical domain of the CIG, as well as a web platform to manually review the alignments and select the appropriate ones. Finally, we present the results of the application of the method to a small corpus of CIGs