Study of the influence of the needle eccentricity on the internal flow in diesel injector nozzles by computational fluid dynamics calculations

In the present paper, a computational study has been performed in order to clarify the effects of the needle eccentricity in a real multihole microsac nozzle. This nozzle has been simulated at typical operating conditions of a diesel engine, paying special attention to the internal flow development and cavitation appearance within the discharge orifices. For that purpose, a multiphase flowsolver based on a homogeneous equilibrium model with a barotropic equation of state has been used, introducing the turbulence effects by Reynolds-averaged Navier Stokes methods with a re-normalization group k-eps model. The results obtained from this investigation have demonstrated the huge influence of the needle position on the flow characteristics, showing important hole to hole differences.This work was partly sponsored by 'Vicerrectorado de Investigacion, Desarrollo e Innovacion' of the 'Universitat Politecnica de Valencia' in the frame of the project 'Estudio de la influencia del uso de combustibles alternativos sobre el proceso de inyeccion mediante GRID computing (FUELGRID)', and by '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), reference TRA2011-26293. This support is gratefully acknowledged by the authors.Salvador Rubio, FJ.; Martínez López, JE.; Romero Bauset, JV.; Roselló Ferragud, MD. (2014). Study of the influence of the needle eccentricity on the internal flow in diesel injector nozzles by computational fluid dynamics calculations. International Journal of Computer Mathematics. 91(1):24-31. https://doi.org/10.1080/00207160.2013.770483S2431911Alajbegovic, 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)00179-6Bermúdez, 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:10.1243/095440705x28303Desantes, 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.2006.10.011Faeth, 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)00059-7F. P. Kärrholm, H. Weller, N. Nordin, Modelling injector flow including cavitation effects for diesel applications. Proceedings of FEDSM, 5th Joint ASME/JSME Fluids Engineering Conference, San Diego, California, July 30–August 2 2007Lee, 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:10.1243/14680874jer00806T. Oda, M. Hiratsuka, Y. Goda, S. Kanaike, and K. Ohsawa,Experimental and numerical investigation about internal cavitating flow and primary atomization of a large-scaled vco diesel injector with eccentric needle. ILASS-Europe 2010, 23rd Annual Conference on Liquid Atomization and Spray Systems, Brno, Czech Republic, September 2010.Park, 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.2004.10.009Payri, 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.2012.01.005Payri, 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., 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. 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Comparison of different techniques for characterizing the diesel injector internal dimensions

[EN] The geometry of certain parts of diesel injectors is key to the injection, atomization and fuel-air mixing phenomena. Small variations on the geometrical parameters may have a strong influence on the aforementioned processes. Thus, OEMs need to assess their manufacturing tolerances, whereas researchers in the field (both experimentalists and modelers) rely on the accuracy of a certain metrology technique for their studies. In the current paper, an investigation of the capability of different experimental techniques to determine the geometry of a modern diesel fuel injector has been performed. For this purpose, three main elements of the injector have been evaluated: the control volume inlet and outlet orifices, together with the nozzle orifices. While the direct observation of the samples through an optical microscope is only possible for the simplest pieces, both Computed Tomography Scanning and the visualization of silicone molds technique have proven their ability to characterize the most complex internal shapes corresponding to the internal injector elements. Indeed, results indicate that the differences observed among these methodologies for the determination of the control volume inlet orifice diameter and the nozzle orifice dimensions are smaller than the uncertainties related to the experimental techniques, showing that they are both equally accurate. This implies that the choice of a given technique for the particular application of determining the geometry of diesel injectors can be done on the basis of availability, intrusion and costs, rather than on its accuracy.This work was partly sponsored by "Ministerio de Economia y Competitividad", of the Spanish Government, in the frame of the Project "Estudio de la interaccion chorro-pared en condiciones realistas de motor", Reference TRA2015-67679-c2-1-R.Salvador, FJ.; Gimeno, J.; De La Morena, J.; Carreres, M. (2018). Comparison of different techniques for characterizing the diesel injector internal dimensions. Experimental Techniques. 42(5):467-472. https://doi.org/10.1007/s40799-018-0246-1S467472425Mobasheri R, Peng Z, Mostafa S (2012) Analysis the effect of advanced injection strategies on engine performance and pollutant emissions in a heavy duty DI-diesel engine by CFD modeling. Int J Heat Fluid Flow 33(1):59–69Dhar A, Agarwal AK (2015) Experimental investigations of the effect of pilot injection on performance, emissions and combustion characteristics of Karanja biodiesel fuelled CRDI engine. Energy Convers Manag 93:357–366Mohan B, Yang W, Chou SK (2013) Fuel injection strategies for performance improvement and emissions reduction in compression ignition engines—a review. Renew Sust Energ Rev 28(x):664–676Petrovic V, Bracanovic Z, Grozdanic B, Petrovic S, Sazhin S, Knezevic D (2015) The design of a full flow dilution tunnel with a critical flow venturi for the measurement of diesel engine particulate emission. FME Trans 43(2):99–106Ilić Z, Rasuo B, Jovanović M, Janković D (2013) Impact of changing quality of air/fuel mixture during flight of a piston engine aircraft with respect to vibration low frequency spectrum. FME Trans 41(1):25–32Luján JM, Tormos B, Salvador FJ, Galgar K (2009) Comparative analysis of a DI diesel engine fuelled with biodiesel blends during the European MVEG-A cycle: Preliminaru study I. Biomass & Bioenergy 33(6–7):941–947Postrioti L, Mariani F, Battistoni M (2012) Experimental and numerical momentum flux evaluation of high pressure diesel spray. Fuel 98:149–163Payri R, Salvador FJ, Gimeno J, Venegas O (2016) A technique to match the refractive index of different diesel fuels with the refractive index of transparent materials to improve the experimental visualization. Exp Tech 40(1):261–269Duran SP, Porter JM, Parker TE (2015) Ballistic imaging of diesel sprays using a picosecond laser: characterization and demonstration. Appl Opt 54(7):1743Payri R, Salvador FJ, Gimeno J et al (2011) Flow regime effects on non-cavitating injection nozzles over spray behavior. Int J Heat Fluid Flow 32(1):273–284Koukouvinis P, Gavaises M, Li J, Wang L (2016) Large Eddy simulation of diesel injector including cavitation effects and correlation to erosion damage. Fuel 175:26–39Som S, Aggarwal SK (2010) Effects of primary breakup modeling on spray and combustion characteristics of compression ignition engines. Combust Flame 157(6):1179–1193Salvador FJ, De la Morena J, Martínez-López J, Jaramillo D (2017) Assessment of compressibility effects on internal nozzle flow in diesel injectors at very high injection pressures. Energy Convers Manag 132:221–230Salvador FJ, Gimeno J, de la Morena J, Martí-Aldaraví P (2012) Using one-dimensional modelling to analyze the influence of the use of biodiesels on the dynamic behaviour of solenoid-operated injectors in common rail systems: Results of the simulation and discussion. Energy Convers Manag 54(1):122–132Taghavifar H, Khalilarya S, Jafarmadar S, Baghery F (2016) 3-D numerical consideration of nozzle structure on combustion and emission characteristics of DI diesel injector. Appl Math Model 40(19–20):8630–8646Edelbauer W (2017) Numerical simulation of cavitating injector flow and liquid spray break-up by combination of Eulerian–Eulerian and volume-of-fluid methods. Comput Fluids 144:19–33Salvador FJ, Carreres M, Jaramillo D, Martínez-López J (2015) Comparison of microsac and VCO diesel injector nozzles in terms of internal nozzle flow characteristics. Energy Convers Manag 103:284–299Salvador FJ, Martínez-López J, Romero JV, Roselló MD (2013) Study of the influence of the needle eccentricity on the internal flow in diesel injector nozzles by computational fluid dynamics calculations. Int J Comput Math 91, no. June:24–31Payri R, Salvador FJ, Carreres M, De la Morena J (Apr. 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 Convers Manag 114:376–391Salvador FJ, Hoyas S, Novella R, Martinez-López J (2011) Numerical simulation and extended validation of two-phase compressible flow in diesel injector nozzles. Proc Inst Mech Eng Part-D-J Automob Eng 225(D4):545–563Satkoski C, Shaver G (2011) Piezoelectric fuel injection: pulse-to-pulse coupling and flow rate estimation. IEEE/ASME Trans Mechatron 16(4):627–642Ferrari A, Mittica A (2016) Response of different injector typologies to dwell time variations and a hydraulic analysis of closely-coupled and continuous rate shaping injection schedules. Appl Energy 169:899–911Payri R, Salvador FJ, Gimeno J, De la Morena J (2011) Analysis of diesel spray atomization by means of a near-nozzle field visualization technique. At Sprays 21(9):753–774Li T, Moon S, Sato K, Yokohata H (Feb. 2017) A comprehensive study on the factors affecting near-nozzle spray dynamics of multi-hole GDI injectors. Fuel 190:292–302Yu W, Yang W, Zhao F (2017) Investigation of internal nozzle flow, spray and combustion characteristics fueled with diesel, gasoline and wide distillation fuel (WDF) based on a piezoelectric injector and a direct injection compression ignition engine. Appl Therm Eng 114:905–920Salvador FJ, Carreres M, Crialesi-Esposito M, Plazas AH (2017) Determination of critical operating and geometrical parameters in diesel injectors through one dimensional modelling, design of experiments and an analysis of variance. Proc Inst Mech Eng Part D J Automob EngMacian V, Bermúdez V, Payri R, Gimeno J (2003) New technique for determination of internal geometry of a diesel nozzle with the use of silicone methodology. Exp Tech 27, no April:39–43Piano A, Millo F, Postrioti L, Biscontini G, Cavicchi A, and Pesce FC, (2016) “Numerical and experimental assessment of a solenoid common-rail injector operation with advanced injection strategies,” SAE Int J Engines 9(1)Mitroglou N, Lorenzi M, Santini M, Gavaises M (2016) Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows. Exp Fluids 57(11):1–14Kastengren AL, Tilocco FZ, Powell CF, Manin J, Pickett LM, Payri R, Bazyn T (2012) Engine combustion network (ECN): measurements of nozzle geometry and hydraulic behavior. At Sprays 22(12):1011–1052Otsu N (1979) A threshold selection method from gray-level histograms. IEEE Trans Syst Man Cybern 9(1):62–6

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

Comparative study of the internal flow in diesel injection nozzles at cavitating conditions at different needle lifts with steady and transient simulations approaches

[EN] The motion of the needle during the injection process of a diesel injector has a marked influence on the internal flow, the fuel characteristics at the nozzle exit, the spray pattern and the fuel-air mixing process. The current paper is focused on the computational study of the internal flow and cavitation phenomena during the injection process, with inclusion of the opening where the needle is working at partial lifts. This study has been performed with a homogeneous equilibrium model (OpenFOAM) customized by the authors to simulate the real motion of the needle. The first part of the study covers the analysis of the whole injection process with a moving mesh using the boundary conditions provided by a one-dimensional (1D) model of the injector created in AMESim. This 1D model has offered the possibility of reproducing the movement of the needle with real lift law and real injection pressure evolution during the injection. Thus, it has been possible to compare the injection rate profiles provided by OpenFOAM against those obtained both in AMESim and experimentally. The second part compares the differences in mass flow, momentum flux, effective velocity and cavitation appearance between steady (fixed lifts) and transient (moving mesh) simulations. The aim of this comparison is to establish the differences between these two approaches. On the one hand is a more realistic approach in its use of transient simulations of the injection process and where the needle movement is taken into account. On the other hand, is the use of steady simulations at partial needle lifts. This analysis could be of interest to researchers devoted to the study of the diesel injection process since it could help to delimit the uncertainties involved in using the second approach which is more easily carried out, versus the first which is supposed to provide more realistic results.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was partly sponsored by the 'Ministerio de Economa y Competitividad' of the Spanish Government, in the frame of the Project 'Estudio de la interaccion chorro-pared en condiciones realistas de motor', Reference TRA2015-67679-c2-1-R.Salvador, FJ.; De La Morena, J.; Crialesi Esposito, M.; Martínez López, J. (2018). 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. https://doi.org/10.1177/0954407017725672S10601078232

Fluid structure interactions within a common rail diesel injector.

The internal flow of a high-pressure diesel injector is simulated numerically to investigate the complex transient flow structures and the unsteady forces imparted to the injector needle that result from the asymmetric flow fields developed during operation. The gas-liquid two phase flow is simulated using a mixture model with the cavitation numerically modeled using the Zwart-Gerber-Belamri model. Both the k-ε model and the detached eddy simulation (DES) model are used, and the numerical results are compared. This dissertation looks at the internal flow of a generic injector at different lifts and characterizes the flow parameters at high lift and low lifts. This paper shows that the DES model captures the important unsteady flow features missed by the k-ε model. A DES simulation of a dual gain orifice injector is performed and the impact of a unique vortical structure that is generated by the gain orifices on the flow characteristics is discussed. The fluid-structure interactions of an injector at hover are simulated and the behavior of this injector and the impact of the resulting lateral bending motion of the needle is discussed. This paper identifies the geometric feature that creates the asymmetrical flow that leads to the bending motion. In the final portion of this dissertation the fluid-structure interactions are simulated over the entire injection cycle. This dissertation discusses how the bending motion of the needle is initiated and develops over the injection cycle and discusses the impact of this motion on the fuel quantity injected and the vapor formed during operation by comparing the FSI simulation to a simulation where the lateral motion is artificially limited

Advanced computational engineering

This is an author's accepted manuscript of an article published in “International Journal of Computer Mathematics"; Volume 91, Issue 1, 2014; copyright Taylor & Francis; available online at: http://dx.doi.org/10.1080/00207160.2014.880256It is with pleasure that we offer the readers of the International Journal of Computer Mathematics this special issue consisting of some of the most significant contributions to computational and mathematical methods with advanced applications in engineering presented at the International Conference on Mathematical Modelling in Engineering & Human Behaviour 2012, held at the Instituto Universitario de Matemática, Multidisciplinar, Polytechnic City of Innovation in Valencia, Spain, September 4–7, 2012, cf. http://jornadas.imm.upv.es/2012/Ehrhardt, M.; Jódar Sánchez, LA.; Villanueva Micó, RJ. (2014). Advanced computational engineering. International Journal of Computer Mathematics. 91(1):1-3. doi:10.1080/00207160.2014.880256S13911Aznar, F., Pujol, M. J., Sempere, M., & Rizo, R. (2013). A macroscopic model for high intensity radiofrequency signal detection in swarm robotics systems. International Journal of Computer Mathematics, 91(1), 32-41. doi:10.1080/00207160.2013.771180Bernal, A., Abarca, A., Barrachina, T., & Miró, R. (2013). Methodology to resolve the transport equation with the discrete ordinates code TORT into the IPEN/MB-01 reactor. International Journal of Computer Mathematics, 91(1), 113-123. doi:10.1080/00207160.2013.799668Castro, M. A., Rodríguez, F., Cabrera, J., & Martín, J. A. (2013). Difference schemes for time-dependent heat conduction models with delay. International Journal of Computer Mathematics, 91(1), 53-61. doi:10.1080/00207160.2013.779371Cornolti, L., Lucchini, T., Montenegro, G., & D’Errico, G. (2013). A comprehensive Lagrangian flame–kernel model to predict ignition in SI engines. International Journal of Computer Mathematics, 91(1), 157-174. doi:10.1080/00207160.2013.829213García-Oliver, J. M., Novella, R., Pastor, J. M., & Winklinger, J. F. (2013). Evaluation of combustion models based on tabulated chemistry and presumed probability density function approach for diesel spray simulation. International Journal of Computer Mathematics, 91(1), 14-23. doi:10.1080/00207160.2013.770844Gibert, K. (2013). Mixed intelligent-multivariate missing imputation. International Journal of Computer Mathematics, 91(1), 85-96. doi:10.1080/00207160.2013.783209González-Pintor, S., Ginestar, D., & Verdú, G. (2013). Preconditioning the solution of the time-dependent neutron diffusion equation by recycling Krylov subspaces. International Journal of Computer Mathematics, 91(1), 42-52. doi:10.1080/00207160.2013.771181Guardiola, C., Pla, B., Blanco-Rodríguez, D., & Reig, A. (2013). Modelling driving behaviour and its impact on the energy management problem in hybrid electric vehicles. International Journal of Computer Mathematics, 91(1), 147-156. doi:10.1080/00207160.2013.829567Montoliu, C., Ferrando, N., Cerdá, J., & Colom, R. J. (2013). Application of the level set method for the visual representation of continuous cellular automata oriented to anisotropic wet etching. International Journal of Computer Mathematics, 91(1), 124-134. doi:10.1080/00207160.2013.801464Montorfano, A., Piscaglia, F., & Onorati, A. (2013). Wall-adapting subgrid-scale models to apply to large eddy simulation of internal combustion engines. International Journal of Computer Mathematics, 91(1), 62-70. doi:10.1080/00207160.2013.783207Ramos-Martínez, E., Herrera, M., Izquierdo, J., & Pérez-García, R. (2013). Ensemble of naïve Bayesian approaches for the study of biofilm development in drinking water distribution systems. International Journal of Computer Mathematics, 91(1), 135-146. doi:10.1080/00207160.2013.808335Salvador, F. J., Martínez-López, J., Romero, J.-V., & Roselló, M.-D. (2013). Study of the influence of the needle eccentricity on the internal flow in diesel injector nozzles by computational fluid dynamics calculations. International Journal of Computer Mathematics, 91(1), 24-31. doi:10.1080/00207160.2013.770483Sastre, J., Ibáñez, J., Ruiz, P., & Defez, E. (2013). Accurate and efficient matrix exponential computation. International Journal of Computer Mathematics, 91(1), 97-112. doi:10.1080/00207160.2013.791392Serrano, J. R., Arnau, F. J., Piqueras, P., & García-Afonso, O. (2013). Application of the two-step Lax and Wendroff FCT and the CE-SE method to flow transport in wall-flow monoliths. International Journal of Computer Mathematics, 91(1), 71-84. doi:10.1080/00207160.2013.783206Zhyrova, A., & Štys, D. (2013). Construction of the phenomenological model of Belousov–Zhabotinsky reaction state trajectory. International Journal of Computer Mathematics, 91(1), 4-13. doi:10.1080/00207160.2013.76633