Engine combustion network: Influence of the gas properties on the spray penetration and spreading angle

In this work, three Engine Combustion Network (ECN) single-hole nozzles with the same nominal characteristics have been tested under a wide range of conditions measuring spray penetration and spreading angle. n-Dodecane has been injected in non-evaporative conditions at different injection pressures ranging from 50 to 150 MPa and several levels of ambient densities from 7.6 to 22.8 kg/m(3). Nitrogen and Sulphur Hexafluoride (SF6) atmospheres have been explored and, in the first case, a temperature sweep from 300 to 550 K at constant gas density has been executed. Mie scattering has been used as the optical technique by employing a fast camera, whereas image processing has been performed through a home-built Mat lab code. Differences in spray penetration related to spray orifice diameter, spreading angle and start of injection transient have been found for the three injectors. Significant differences have been obtained when changing the ambient gas, whereas ambient temperature hardly affects the spray characteristics up to 400 K. However, a reduction in penetration has been observed beyond this point, mainly due to the sensitivity limitation of the technique as fuel evaporation becomes important. The different behavior observed when injecting in different gases could be explained due to the incomplete momentum transfer between spray droplets and entrained gas, together with the fact that there is an important change in speed of sound for the different gases, which affects the initial stage of the injection. (C) 2014 Elsevier Inc. All rights reserved.This work was sponsored by "Ministerio de Economia y Competitividad" of the Spanish Government in the frame of the Project "Comprension de la influencia de combustibles no convencionales en el proceso de injeccion y combustion tipo diesel", Reference TRA2012-36932.Payri González, F.; Payri Marín, R.; Bardi, M.; Carreres Talens, M. (2014). Engine combustion network: Influence of the gas properties on the spray penetration and spreading angle. Experimental Thermal and Fluid Science. 53:236-243. https://doi.org/10.1016/j.expthermflusci.2013.12.014S2362435

A New Tool to Perform Global Energy Balances in DI Diesel Engines 2014-01-0665

[EN] The generalization of exhaust aftertreatment systems along with the growing awareness about climate change is leading to an increasing importance of the efficiency over other criteria during the design of reciprocating engines. Using experimental and theoretical tools to perform detailed global energy balance (GEB) of the engine is a key issue for assessing the potential of different strategies to reduce consumption. With the objective of improving the analysis of GEB, this paper describes a tool that allows calculating the detailed internal repartition of the fuel energy in DI Diesel engines. Starting from the instantaneous in-cylinder pressure, the tool is able to describe the different energy paths thanks to different submodels for all the relevant subsystems. Hence, the heat transfer from gases to engine walls is obtained with specific convective and radiative models in the chamber and ports; the repartition of the heat flux throughout the engine metal elements towards the oil and coolant is estimated with a lumped capacitance model; finally, the ancillary systems and friction losses are obtained through specific semiempirical submodels. The validation of the tool is performed in a 4- cylinder DI Diesel engine instrumented to perform detailed experimental GEB. Finally, a simple analysis of combined internal and external analysis in the complete engine map shows the effect of operating conditions on each energy term. Thus it is demonstrated the utility of the proposed tool, that complements the experimental heat flow measurements in Diesel engine researches oriented to the reduction of energy consumption.The support of the Universitat Politècnica de València (PAID06-09) and Generalitat Valenciana (GV/2010/045) is greatly acknowledged.Payri González, F.; Olmeda González, PC.; Martín Díaz, J.; Carreño, R. (2014). A New Tool to Perform Global Energy Balances in DI Diesel Engines 2014-01-0665. SAE International Journal of Engines. 7(1):1-17. doi:10.4271/2014-01-0665S1177

A complete 0D thermodynamic predictive model for direct injection diesel engines

[EN] Ideal models provide the simplest way to reproduce internal combustion engine (ICE) cycles, but they usually do not represent with sufficient accuracy the actual behaviour of an ICE. A suitable alternative for research and development applications is provided by zero-dimensional (0D) thermodynamic models. Such models are very useful for predicting the instantaneous pressure and temperature in the combustion chamber, which in turn allows the prediction of engine operation characteristics. However, they use simplifying hypotheses which lead, in some cases, to a lack of accuracy or a limited predictive capability.This paper describes a 0D single-zone thermodynamic model that takes into account the heat transfer to the chamber walls, the blow-by leakage, the fuel injection and engine deformations, along with the instantaneous change in gas properties. Special attention has been paid to the description of the specific sub-models that have been used for the calculation of the energy and mass equations terms. The procedures followed for the estimation of some mechanical and heat transfer parameters and the combustion model fitting are also detailed. After the fitting, the model was validated in different operation points in a 4-cylinder 2-l DI diesel engine, showing a good capability for accurate predictions of engine performance and the gas state in the closed cycle. © 2011 Elsevier Ltd.The authors thank the Universitat Politecnica de Valencia (PAID-06-09) and Generalitat Valenciana (GV/2010/045) for their valuable support to this work and the referees for their worthy comments.Payri González, F.; Olmeda, P.; Martín Díaz, J.; García Martínez, A. (2011). A complete 0D thermodynamic predictive model for direct injection diesel engines. Applied Energy. 88:4632-4641. doi:10.1016/j.apenergy.2011.06.005S463246418

Influence of the chemical mechanism in the frame of diesel-like CFD reacting spray simulations using a presumed PDF flamelet-based combustion model

[EN] The ability of a computational fluid dynamics (CFD) simulation to reproduce the diesel-like reacting spray ignition process and its corresponding flame structure strongly depends on both the fidelity of the chemical mechanism for reproducing the oxidation of the fuel and also on how the turbulence-chemistry interaction (TCI) is modeled. Therefore, investigating the performance of different chemical mechanisms not only in perfect stirred reactors but directly in the diesel-like spray itself is of great interest in order to evaluate their suitability for being further applied to CFD engine simulations. This research work focuses on applying a presumed probability density function (PDF) unsteady flamelet combustion model to the well-known spray A from the Engine Combustion Network (ECN), using three chemical mechanisms widely accepted by the scientific community as a way to figure out the influence of chemistry in the key characteristics of the combustion process in the frame of diesel-like spray simulations. Results confirm that in spite of providing all of them correct trends for ignition delays (ID) and lift-off lengths (LOL), when comparing with experimental results, the structure of the flame presents noticeable differences, especially in the low and intermediate temperatures and high equivalence ratio regions. Consequently, the selection of the chemical mechanism has an impact on the zones of influence of key species as observed in both spatial coordinates and also in the equivalence ratio-temperature maps. These differences are expected to be relevant considering the implications when coupling pollutant emissions models. The analysis of temperature and oxygen concentration parametric studies evidences how the observed differences are consistent and moderately dependent on the ambient conditions.Authors acknowledge that this work was possible thanks to the Ayuda para la Formación de Profesorado Universitario (FPU 14/03278) belonging to the Subprogramas de Formación y de Movilidad del Ministerio de Educación, Cultura y Deporte from Spain. Also this study was partially funded by the Ministerio de Economía y Competitividad from Spain in the frame of the COMEFF (TRA2014-59483-R) national project.Payri González, F.; García Oliver, JM.; Novella Rosa, R.; Pérez Sánchez, EJ. (2017). Influence of the chemical mechanism in the frame of diesel-like CFD reacting spray simulations using a presumed PDF flamelet-based combustion model. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 678-685. https://doi.org/10.4995/ILASS2017.2017.4746OCS67868

A contribution to the understanding of cavitation effects in Diesel injector nozzles through a combined experimental and computational investigation

In this paper a combined experimental and computational study was carried out in order to assess the ability of a homogeneous equilibrium model in predicting the experimental behaviour observed from the hydraulical characterization of a nozzle. The nozzle used was a six-orifice microsac nozzle, with cylindrical holes, and therefore inclined to cavitate. The experimental results available for the validation purpose comprised measurements of mass flow rate and spray momentum flux, which correctly combined provide also fundamental information such as discharge coefficient, nozzle exit effective velocity and area contraction. The model was proved to be able of reproducing the experimental results with high degree of confidence and, through the exploration of the internal flow, allowed the explanation of widely reported experimental findings related to cavitation phenomena: the mass flow choking induced by cavitation and the increment of effective injection velocity.This work was partly sponsored by "Vicerrectorado de lnvestigacion, Desarrollo e Innovacion" of the "Universitat Politecnica de Valencia" in the frame of the Project "Estudio del flujo en toberas de inyeccion diesel mediante tecnicas LES (LESFLOWGRID)", Reference No. 2837 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.Payri González, F.; Payri, R.; Salvador Rubio, FJ.; Martínez López, J. (2012). A contribution to the understanding of cavitation effects in Diesel injector nozzles through a combined experimental and computational investigation. Computers and Fluids. 58:88-101. doi:10.1016/j.compfluid.2012.01.005S881015

MOTORES DE COMBUSTIÓN INTERNA ALTERNATIVOS

Esta obra está dirigida a estudiantes que cursan asignaturas tanto básicas como avanzadas sobre Motores de Combustión Interna Alternativos (MCIA) en carreras de ingeniería o en cursos de postgrado (maestrías), pero su contenido también puede ser de utilidad a todas aquellas personas interesadas en la materia. Se ha puesto especial atención en los conceptos "permanentes", es decir, aquellos conceptos fundamentales poco susceptibles de cambiar en un horizonte de vida razonable para un libro de texto. Además se ha procurado poner énfasis en los procesos termofluidodinámicos de los MCIA, y por ello se tratan con detalle. También se incluye material sobre la cinemática y dinámica del motor, así como temas relacionados con sus elementos constructivos. De este modo se pretende proporcionar al lector una visión global de los MCIA.Payri González, F.; Desantes Fernández, JM. (2011). MOTORES DE COMBUSTIÓN INTERNA ALTERNATIVOS. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/70998EDITORIA

Thiesel 2014 (Thermo-and fluid dynamic processes in direct injection engines)

Thiesel is presented as a valuable platform for exchange of the latest international work and disseminates the results of research to improve engine efficiency and reduce emissions. It provides an ideal opportunity to share theories and methods that provide solutions that respect the environment, and generate great excitement and interest in the automotive industry with the latest discoveries and technologies.Angelberger, C.; Desantes Fernández, JM.; Arcoumanis, C.; Payri González, F.; Margot, XM. (2014). Thiesel 2014 (Thermo-and fluid dynamic processes in direct injection engines). Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/44213Archivo delegad