Numerical Estimation of Wiebe Function Parameters Using Artificial Neural Networks in SI Engine

[EN] In modeling an Internal Combustion Engine, the combustion sub-model plays a critical role in the overall simulation of the engine as it provides the Mass Fraction Burned (MFB). Analytically, the Heat Release Rate (HRR) can be obtained using the Wiebe function, which is nothing more than a mathematical formulation of the MFB. The mentioned function depends on the following four parameters: efficiency parameter, shape factor, crankshaft angle, and duration of the combustion. In this way, the Wiebe function can be adjusted to experimentally measured values of the mass fraction burned at various operating points using a least-squares regression, and thus obtaining specific values for the unknown parameters. Nevertheless, the main drawback of this approach is the requirement of testing the engine at a given engine load/speed condition. Furthermore, the main objective of this study is to propose a predictive model of the Wiebe parameters for any operating point of the tested SI engine. For this purpose, an Artificial Neural Network (ANN) is developed from the experimental data. A criterion was defined to choose the best-trained network. Finally, the Wiebe parameters are estimated with the neural networks for different operating conditions. Moreover, the mass fractions burned generated from the Wiebe functions are compared with the respective experimental values from several operating points measured in the engine test bench. Small differences were found between the estimated and experimental mass fractions burned. Therefore, the effectiveness of the developed ANN model as a prediction tool for the engine MFB is verified.Torregrosa, AJ.; Broatch, A.; Olmeda, P.; Aceros, S. (2021). Numerical Estimation of Wiebe Function Parameters Using Artificial Neural Networks in SI Engine. SAE International. 1-10. https://doi.org/10.4271/2021-01-037911

Assessment of the improvement of internal combustion engines cooling system using nanofluids and nanoencapsulated phase change materials

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/10.1177/1468087420917494[EN] In recent years, due to the increasing need to reduce consumption of reciprocating internal combustion engines, new researches on different subsystems have raised. Among them, the use of nanofluids as a coolant medium seems to be an interesting alternative. In this work, the potential benefits of using nanofluids in the cooling system using an engine lumped model are studied. The methodology of the study starts with a whole description and validation of the model in both steady and transient conditions by means of a comparison with experimental results. Then, the potential benefits that could be obtained with the use of nanofluids are studied in a theoretical way. After that, the model is used to estimate the behavior of the system using different nanofluids in both stationary and transient conditions. The main results show that the advantages of using these new refrigerants are limited.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 "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica 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.Torregrosa, AJ.; Broatch, A.; Olmeda, P.; Dreif-Bennany, A. (2021). Assessment of the improvement of internal combustion engines cooling system using nanofluids and nanoencapsulated phase change materials. International Journal of Engine Research. 22(6):1939-1957. https://doi.org/10.1177/1468087420917494S1939195722

A sparse mesh for Compact Finite Difference Fourier solvers with radius-dependent spectral resolution in circular domains

This paper presents a new method for the resolution of elliptic and parabolic equations in circular domains. It can be trivially extended to cylindrical domains. The algorithm uses a mixed Fourier-Compact Finite Difference method. The main advantage of the method is achieved by a new concept of mesh. The topology of the new grid keeps constant the aspect ratio of the cells, avoiding the typical clustering for radial structured meshes at the center. The reduction of the number of nodes has as a consequence the reduction in memory consumption. In the case of fluid mechanics problems, this technique also increases the time step for a constant Courant number. Several examples are given in the paper which show the potential of the method. (C) 2014 Elsevier Ltd. All rights reservedThis work was supported by the Spanish Government in the frame of the Project "Metodos LES para la simulacion de chorros multifasicos", grant ENE2010-18542. We also are very grateful to one of the referees for his/her work.Torregrosa, AJ.; Hoyas, S.; Gil, A.; García Galache, JP. (2014). A sparse mesh for Compact Finite Difference Fourier solvers with radius-dependent spectral resolution in circular domains. Computers and Mathematics with Applications. 67(6):1309-1318. https://doi.org/10.1016/j.camwa.2014.01.020S1309131867

Numerical approach for assessing combustion noise in compression-ignited Diesel engines

[EN] Diesel combustion noise has become a crucial aspect for the engine manufacturers due to its impact on human health and influence on the customer purchasing decision. The interaction of the pressure waves after mixture self-ignition induces cavity resonances inside the combustion chamber. This complex phenomenon produces high-frequency pressure oscillations, hence traditional in-cylinder measurements do not provide enough information to characterise the in-cylinder acoustic field. In this paper, a numerical methodology is proposed for assessing the Diesel combustion as a noise source and to overcome measurement limitations. An optimisation procedure is also presented in order to determine the numerical calculation parameters, boundary conditions definition and initialization. Results show that local flow conditions at the start of combustion have a strong influence on the acoustic response of the in-cylinder noise source. These particular conditions are only achievable by the proposed methodology which considers entire engine cycle simulations with the complete cylinder domain. Therefore, traditional Computational Fluid Dynamic (CFD) approaches, such those used for predicting combustion stability or pollutant emissions, are not suitable for reproducing the physical mechanisms of noise generation and they cannot be used for acoustic purposes. The reliability of the proposed methodology to simulate the acoustic field accurately inside the combustion chamber has been validated by comparison with experiments.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 Energdtica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)", framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economia y Competitividad. J. Gomez-Soriano is partially supported through the "Programa de Apoyo para la Investigacion y Desarrollo (PAID)" of Universitat Politecnica de Valencia [Grant No. FPI-S2-2016-1353].Torregrosa, AJ.; Broatch, A.; Gil, A.; Gómez-Soriano, J. (2018). Numerical approach for assessing combustion noise in compression-ignited Diesel engines. Applied Acoustics. 135:91-100. https://doi.org/10.1016/j.apacoust.2018.02.006S9110013

Estimation of the in-cylinder residual mass fraction at Intake Valve Closing in a 2-stroke High-Speed Direct-Injection Compression-Ignition engine

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/10.1177/1468087418813406.[EN] New combustion concepts and engine designs are being currently investigated in order to comply with upcoming pollutant regulations and reduce fuel consumption. In this context, two-stroke architectures appear as a promising solution for the implementation of some combustion concepts. However, scavenging processes in a two-stroke engine are much more challenging than for a four-stroke engine, and the residual mass of burnt gases retained inside the cylinder needs to be properly determined in order to keep control over the in-cylinder composition, hence over the combustion conditions and pollutant emissions. In this study, a new methodology for the estimation of the internal residual gas fraction is introduced, which is based on the thermodynamic processes occurring in the engine investigated and makes use of basic engine instrumentation and measurement equipment usually available in a conventional test cell. Several versions of the estimator were developed so that different requirements could be met, such as those of real-time estimation on an engine test bench but with reduced precision or, on the contrary, highly precise but time-consuming computations for post-processing purposes and combustion diagnosis. The consistency of the internal residual gas estimator was then validated through its application to real engine tests at different operating points.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research has been sponsored by the European Union in framework of the REWARD project, Horizon 2020 research and innovation program under grant agreement no. 636380. The authors kindly recognize the technical support provided by Mr Gilles Coma and his research group at RENAULT SAS, and also by the research group at IFPEN, along the development of the investigations presented here.Torregrosa, AJ.; Martín, J.; Novella Rosa, R.; Thein, K. (2020). Estimation of the in-cylinder residual mass fraction at Intake Valve Closing in a 2-stroke High-Speed Direct-Injection Compression-Ignition engine. International Journal of Engine Research. 21(5):838-855. https://doi.org/10.1177/1468087418813406S838855215Galindo, J., Luján, J. M., Serrano, J. R., & Hernández, L. (2005). Combustion simulation of turbocharger HSDI Diesel engines during transient operation using neural networks. Applied Thermal Engineering, 25(5-6), 877-898. doi:10.1016/j.applthermaleng.2004.08.004Payri, F., Benajes, J., Galindo, J., & Serrano, J. R. (2002). Modelling of turbocharged diesel engines in transient operation. Part 2: Wave action models for calculating the transient operation in a high speed direct injection engine. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 216(6), 479-493. doi:10.1243/09544070260137507Rakopoulos, C. ., Rakopoulos, D. ., Giakoumis, E. ., & Kyritsis, D. . (2004). Validation and sensitivity analysis of a two zone Diesel engine model for combustion and emissions prediction. Energy Conversion and Management, 45(9-10), 1471-1495. doi:10.1016/j.enconman.2003.09.012Gatowski JA, Balles EN, Chun KM, Nelson FE, Ekchian JA, Heywood JB. Heat release analysis of engine pressure data. SAE technical paper 841359, 1984.Lapuerta, M., Armas, O., & Hernández, J. J. (1999). Diagnosis of DI Diesel combustion from in-cylinder pressure signal by estimation of mean thermodynamic properties of the gas. Applied Thermal Engineering, 19(5), 513-529. doi:10.1016/s1359-4311(98)00075-1Arrègle, J., López, J. J., Garcı́a, J. M., & Fenollosa, C. (2003). Development of a zero-dimensional Diesel combustion model. Part 1: Analysis of the quasi-steady diffusion combustion phase. Applied Thermal Engineering, 23(11), 1301-1317. doi:10.1016/s1359-4311(03)00079-6Arrègle, J., López, J. J., Garcı́a, J. M., & Fenollosa, C. (2003). Development of a zero-dimensional Diesel combustion model. Applied Thermal Engineering, 23(11), 1319-1331. doi:10.1016/s1359-4311(03)00080-2Li J, Chae JO, Park SB, Paik HJ, Park JK, Jeong YS, et al. Effect of intake composition on combustion and emission characteristics of DI diesel engine at high intake pressure. SAE technical paper 970322, 1997.Brown WL. Methods for evaluating requirements and errors in cylinder pressure measurement. SAE technical paper 670008, 1968.Lancaster DR, Krieger RB, Lienesch JH. Measurement and analysis of engine pressure data. SAE technical paper 750026, 1975.Ghojel, J., & Honnery, D. (2005). Heat release model for the combustion of diesel oil emulsions in DI diesel engines. Applied Thermal Engineering, 25(14-15), 2072-2085. doi:10.1016/j.applthermaleng.2005.01.016Wu, Y., Wang, Y., Zhen, X., Guan, S., & Wang, J. (2014). Three-dimensional CFD (computational fluid dynamics) analysis of scavenging process in a two-stroke free-piston engine. Energy, 68, 167-173. doi:10.1016/j.energy.2014.02.107Yuan, C., Feng, H., He, Y., & Xu, J. (2016). Combustion characteristics analysis of a free-piston engine generator coupling with dynamic and scavenging. Energy, 102, 637-649. doi:10.1016/j.energy.2016.02.131Cheung HM, Heywood JB. Evaluation of a one-zone burn-rate analysis procedure using production SI engine pressure data. SAE technical paper 932749, 1993.Brunt, M. F. J., Rai, H., & Emtage, A. L. (1998). The Calculation of Heat Release Energy from Engine Cylinder Pressure Data. SAE Technical Paper Series. doi:10.4271/981052Payri, F., Molina, S., Martín, J., & Armas, O. (2006). Influence of measurement errors and estimated parameters on combustion diagnosis. Applied Thermal Engineering, 26(2-3), 226-236. doi:10.1016/j.applthermaleng.2005.05.006Broatch, A., Ruiz, S., Margot, X., & Gil, A. (2010). Methodology to estimate the threshold in-cylinder temperature for self-ignition of fuel during cold start of Diesel engines. Energy, 35(5), 2251-2260. doi:10.1016/j.energy.2010.02.012Olsen, D. B., Hutcherson, G. C., Willson, B. D., & Mitchell, C. E. (2002). Development of the Tracer Gas Method for Large Bore Natural Gas Engines—Part I: Method Validation. Journal of Engineering for Gas Turbines and Power, 124(3), 678-685. doi:10.1115/1.1454116Olsen, D. B., Hutcherson, G. C., Willson, B. D., & Mitchell, C. E. (2002). Development of the Tracer Gas Method for Large Bore Natural Gas Engines—Part II: Measurement of Scavenging Parameters. Journal of Engineering for Gas Turbines and Power, 124(3), 686-694. doi:10.1115/1.1454117Benajes, J., Olmeda, P., Martín, J., & Carreño, R. (2014). A new methodology for uncertainties characterization in combustion diagnosis and thermodynamic modelling. Applied Thermal Engineering, 71(1), 389-399. doi:10.1016/j.applthermaleng.2014.07.010Payri, F., Olmeda, P., Martín, J., & García, A. (2011). A complete 0D thermodynamic predictive model for direct injection diesel engines. Applied Energy, 88(12), 4632-4641. doi:10.1016/j.apenergy.2011.06.005Benajes, J., Novella, R., De Lima, D., Tribotté, P., Quechon, N., Obernesser, P., & Dugue, V. (2013). Analysis of the combustion process, pollutant emissions and efficiency of an innovative 2-stroke HSDI engine designed for automotive applications. Applied Thermal Engineering, 58(1-2), 181-193. doi:10.1016/j.applthermaleng.2013.03.050Benajes, J., Martín, J., Novella, R., & Thein, K. (2016). Understanding the performance of the multiple injection gasoline partially premixed combustion concept implemented in a 2-Stroke high speed direct injection compression ignition engine. Applied Energy, 161, 465-475. doi:10.1016/j.apenergy.2015.10.034Benajes, J., Novella, R., De Lima, D., & Thein, K. (2017). Impact of injection settings operating with the gasoline Partially Premixed Combustion concept in a 2-stroke HSDI compression ignition engine. Applied Energy, 193, 515-530. doi:10.1016/j.apenergy.2017.02.044Galindo, J., Serrano, J. R., Arnau, F. J., & Piqueras, P. (2009). Description of a Semi-Independent Time Discretization Methodology for a One-Dimensional Gas Dynamics Model. Journal of Engineering for Gas Turbines and Power, 131(3). doi:10.1115/1.2983015CARREÑO ARANGO, R. (s. f.). A comprehensive methodology to analyse the Global Energy Balance in Reciprocating Internal Combustion Engines. doi:10.4995/thesis/10251/73069Benajes, J., Olmeda, P., Martín, J., Blanco-Cavero, D., & Warey, A. (2017). Evaluation of swirl effect on the Global Energy Balance of a HSDI Diesel engine. Energy, 122, 168-181. doi:10.1016/j.energy.2017.01.082Payri, F., López, J. J., Martín, J., & Carreño, R. (2018). Improvement and application of a methodology to perform the Global Energy Balance in internal combustion engines. Part 1: Global Energy Balance tool development and calibration. Energy, 152, 666-681. doi:10.1016/j.energy.2018.03.11

A Reduced Order Model based on Artificial Neural Networks for nonlinear aeroelastic phenomena and application to composite material beams

[EN] Applications of composite materials in industry have increased due to their high stiffness-to-weight ratio. In the particular case of unidirectional fibers or perpendicular fabrics, the materials behavior is orthotropic, so that an extra degree of freedom, related to the orientation of the fibers, must be included in the structural optimization. Composite material thin walled beam models have been developed for reducing the computational cost of the simulations. Traditionally, these models have been coupled with potential aerodynamics to calculate the aeroelastic response, and thus, the viscous nonlinear effects have been omitted. In order to capture these effects, this manuscript focus on the development of a Reduced Order Model enhanced by an Artificial Neural Network for the analysis of composite structures under aerodynamic loads. The presented methodology shows the training process of the neural network, the comparison with high fidelity simulations and the design optimization of a carbon fiber laminated foam beam. It is demonstrated that the model reduces the computational cost by orders of magnitude, while still capturing structural couplings and being capable of increasing the flutter velocity by more than 10% with respect to the longitudinal orientation.This project have been partially funded by Spanish Ministry of University through the University Faculty Training (FPU) program with reference FPU19/02201.Torregrosa, AJ.; Gil, A.; Quintero-Igeño, P.; Cremades-Botella, A. (2022). A Reduced Order Model based on Artificial Neural Networks for nonlinear aeroelastic phenomena and application to composite material beams. Composite Structures. 295:1-15. https://doi.org/10.1016/j.compstruct.2022.11584511529

Enhanced design methodology of a low power stall regulated wind turbine. BEMT and MRF-RANS combination and comparison with existing designs

[EN] Wind energy importance has increased over the past decades. Energy generation by small turbines installed near urban locations has experienced noticeable growth. This work is focused on the development of a design methodology for a low power blade well suited for all the wind operation conditions. First, a complete Design of Experiments will be presented using the low computational cost tool Blade Element Momentum Theory (BEMT) in order to discard those designs which are clearly not suited to the requirements of the system. Later, the remaining were analyzed using a Computational Fluid Dynamics (CFD) methodology in order to account for three dimensional effects. The value of the left slope of the non-dimensional power curve has been found to be a key parameter for the design. This methodology has been validated with experimental results available from NREL Phase VI wind turbine, allowing to conclude that BEMT is capable to provide with pre-design accurate results which, nevertheless, should corrected by CFD. The results of the proposed design are analyzed and compared to the CFD predictions of a commercial existing blade designed to comply with similar working. For the proposed design, predictions indicate better behavior in terms of maximum power and controllability.Torregrosa, AJ.; Gil, A.; Quintero-Igeño, P.; Tiseira, A. (2019). Enhanced design methodology of a low power stall regulated wind turbine. BEMT and MRF-RANS combination and comparison with existing designs. Journal of Wind Engineering and Industrial Aerodynamics. 190:230-244. https://doi.org/10.1016/j.jweia.2019.04.019S23024419

Experimental and computational approach to the transient behaviour of wall-flow diesel particulate filters

[EN] The implementation of tight vehicle emission standards has forced manufactures to use aftertreatment systems extensively. In addition to pollutant emissions abatement, these devices have a noticeable impact on the wave pattern. This fact affects the muffler design criteria. All monolithic aftertreatment devices produces a damping effect because of the honeycomb structure and the narrow channels. However, this response is more marked in wall-flow diesel particulate filters (DPF) because of the alternatively plugged ends and the dissipative properties of the porous substrate. The main goal of this paper is to assess the transient fluid-dynamic behaviour of wall-flow DPFs using experimental and modelling techniques. The experimental data were gathered in clean and loaded conditions. The DPF was subjected to a variety of pressure excitations to characterise its transient behaviour in the time and frequency domains. Afterwards, the DPF response was evaluated under engine-like operating conditions in an unsteady flow gas stand. Once the main characteristics of the response were known, a non-linear gas-dynamics model was proposed for analysis and prediction. The model accounts for space and time gradients, combining the thermo-and fluid-dynamic solution with a model based on a packed bed of spherical particles that defines the meso-structure of the loaded substrate. (C) 2016 Elsevier Ltd. All rights reserved.This work has been partially supported by the Spanish Ministerio de Economia y Competitividad through Grant No. TRA2013-40853-R.Torregrosa, AJ.; Serrano, J.; Piqueras, P.; García Afonso, Ó. (2017). Experimental and computational approach to the transient behaviour of wall-flow diesel particulate filters. Energy. 119:887-900. https://doi.org/10.1016/j.energy.2016.11.051S88790011