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Journal articles on the topic 'Stratified charge engines Models'

Author: Grafiati

Published: 4 June 2021

Last updated: 15 February 2022

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Han, Z., Z. Xu, and N. Trigui. "Spray/wall interaction models for multidimensional engine simulation." International Journal of Engine Research 1, no. 1 (2000): 127–46. http://dx.doi.org/10.1243/1468087001545308.

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Models were developed to describe the spray wall impingement processes that take place in internal combustion engines. In this report focus is placed on the model formulation and experiment assessment of the spray/wall interaction submodels. It is identified that the Leidenfrost phenomenon is very unlikely to occur in a spark ignition (SI) engine including stratified-charge operation in a direct injection spark ignition (DISI) engine. A more comprehensive splashing/deposition threshold function is proposed to include the effects of surface roughness and pre-existing liquid film. Based on the wave phenomena observed on the surface of the liquid crown formed during drop impingement, a new splash breakup model is developed using linear instability analysis. The predicted drop size agrees well with available single-drop impingement experimental data. A new formulation for the post-impingement droplet velocity is also given which uses statistical sampling and jet impingement theory. The proposed models were assessed by comparing computations with two sets of experimental sprays impinging on a flat plate with the use of a pintle nozzle injector for port fuel injection (PFI) engines. The computed spray shape, normal and tangential penetration and droplet size show good agreement with experimental data.

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Xu, Bo Yan, De Zhi Sun, Yun Liang Qi, Yong Wei Zheng, Hai Ying Tian, and Shao Li Cai. "Study on Mixture Formation of Liquid LPG for a Center Injection DISI Engine." Advanced Materials Research 201-203 (February 2011): 622–26. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.622.

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Center injection in pentroof combustion chamber can reduce wall wetting and unburned hydrocarbon emission in wall guided combustion system, which is generally employed in DISI (Direct Injection Spark Ignition) engines. Once liquid phase LPG (Liquefied Petroleum Gas) is injected at a high pressure, flash boiling occurs severely, promotes mixing and reduces wall wetting in wall guided engine. Based on validating the feasibility of the models, this paper numerically simulates the mixing process of a center injection wall guided DISI engine in different conditions. The results show that a stratified charge can obtained at part load with late injection, whereas at high load the early injection can achieve a homogeneous mixture at the end of compression stroke.

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Smith, Jamie Karl, Phil Roberts, Alexandros Kountouriotis, David Richardson, Pavlos Aleiferis, and Daniel Ruprecht. "Thermodynamic modelling of a stratified charge spark ignition engine." International Journal of Engine Research 21, no. 5 (2018): 801–10. http://dx.doi.org/10.1177/1468087418784845.

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Combustion of a charge with spatially and temporally varying equivalence ratio in a spark ignition engine was modelled using the Leeds University Spark Ignition Engine quasi-dimensional thermodynamic code. New sub-models have been integrated into Leeds University Spark Ignition Engine that simulate the effect of burnt gas expansion and turbulent mixing on an initial equivalence ratio distribution. Realistic distribution functions were used to model the radially varying equivalence ratio. The new stratified fuel model was validated against experimental data, showing reasonable agreement for both the pressure trace and percentage heat released. Including the effect of turbulent mixing was found to be important to reproduce the trend in the differences between the stratified and homogeneous simulations.

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Cho, K.-W., D. Assanis, Z. Filipi, G. Szekely, P. Najt, and R. Rask. "Experimental investigation of combustion and heat transfer in a direct-injection spark ignition engine via instantaneous combustion chamber surface temperature measurements." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 222, no. 11 (2008): 2219–33. http://dx.doi.org/10.1243/09544070jauto853.

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An experimental study was performed to provide the combustion and in-cylinder heat transfer characteristics resulting from different injection strategies in a direct-injection spark ignition (DISI) engine. Fast-response thermocouples were embedded in the piston top and cylinder head surface to measure the instantaneous combustion chamber surface temperature and heat flux, thus providing critical information about the combustion characteristics and a thorough understanding of the heat transfer process. Two distinctive operating modes, homogeneous and stratified, were considered and their effect on combustion and heat transfer in a DISI engine was investigated. The stratified operating mode yielded significantly higher spatial variations of heat flux than the homogeneous mode. This behaviour is directly caused by the main features of stratified combustion, i.e. vigorous burning of a close-to-stoichiometric mixture near the spark, and a cool, extremely lean mixture at the periphery. The cooling effect of the spray impinging on the piston surface when the fuel is injected late in compression could be detected too. The local phenomena change with varying speed and injection parameters. Comparison between the calculated global heat fluxes and measured local heat fluxes were performed in order to assess the behaviour of classic heat transfer models. Comparisons between the global and local heat fluxes provide additional insight into spatial variations, as well as indications about the suitability of different classic models for investigations of the heat transfer aspect of DISI engines. Special consideration is required when applying classic heat transfer correlations to stratified DISI operation as heat flux values are lower by more than 30 per cent when compared with homogeneous operation of the same engine at the same load.

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Cao, Li, Hua Zhao, Xi Jiang, and Navin Kalian. "Understanding the infiuence of valve timings on controlled autoignition combustion in a four-stroke port fuel injection engine." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, no. 6 (2005): 807–23. http://dx.doi.org/10.1243/095440705x11077.

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Controlled autoignition (CAI) combustion, also known as homogeneous charge compression ignition (HCCI), was achieved through the negative valve overlap approach by using small- lift camshafts. Three-dimensional multicycle engine simulations were carried out in order better to understand the effects of variable intake valve timings on the gas exchange process, mixing quality, CAI combustion, and pollutant formation in a four-stroke port fuel injection (PFI) gasoline engine. Full engine cycle simulation, including complete gas exchange and combustion processes, was carried out over several cycles in order to obtain the stable cycle for analysis. The combustion models used in the present study are a modified shell ignition model and a laminar and turbulent characteristic time model, which can take high residual gas fraction into account. After the validation of the model against experimental data, investigations of the effects of variable intake valve timing strategies on the CAI combustion process were carried out. These analyses show that the intake valve opening (IVO) and intake valve closing (IVC) timings have a strong infiuence on the gas exchange and mixing processes in the cylinder, which in turn affect the engine performance and emissions. Symmetric IVO timing relative to exhaust valve closing (EVC) timing tends to produce a more stratified mixture, earlier ignition timing, and localized combustion, and hence higher NO x and lower unburned HC and CO emissions, whereas retarded IVO leads to faster mixing, a more homogeneous mixture, and uniform temperature distribution.

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Li, Tie, Keiya Nishida, Yuyin Zhang, Tuyoshi Onoe, and Hiroyuki Hiroyasu. "Enhancement of Stratified Charge for DISI Engines through Split Injection : Effect and Its Mechanism(S.I. Engines, Stratified-Charge Combustion)." Proceedings of the International symposium on diagnostics and modeling of combustion in internal combustion engines 2004.6 (2004): 521–28. http://dx.doi.org/10.1299/jmsesdm.2004.6.521.

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Dinc, Cenk, Hikmet Arslan, and Rafig Mehdiyev. "CO2Emission Reduction Using Stratified Charge in Spark-Ignition Engines†." Energy & Fuels 23, no. 4 (2009): 1781–85. http://dx.doi.org/10.1021/ef800349x.

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Li, Yufeng, Hua Zhao, Ben Leach, and Tom Ma. "Charge Stratification in a Strong Tumble SI Engine(S.I. Engines, Stratified-Charge Combustion)." Proceedings of the International symposium on diagnostics and modeling of combustion in internal combustion engines 2004.6 (2004): 505–12. http://dx.doi.org/10.1299/jmsesdm.2004.6.505.

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Giorgetti, N., G. Ripaccioli, A. Bemporad, I. V. Kolmanovsky, and D. Hrovat. "Hybrid Model Predictive Control of Direct Injection Stratified Charge Engines." IEEE/ASME Transactions on Mechatronics 11, no. 5 (2006): 499–506. http://dx.doi.org/10.1109/tmech.2006.882979.

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Duclos, J. M., T. Baritaud, and A. Fusco. "Modeling Turbulent Combustion and Pollutant Formation in Stratified Charge Si Engines." Revue de l'Institut Français du Pétrole 52, no. 5 (1997): 541–52. http://dx.doi.org/10.2516/ogst:1997059.

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Baritaud, T. A., J. M. Duglos, and A. Fusco. "Modeling turbulent combustion and pollutant formation in stratified charge SI engines." Symposium (International) on Combustion 26, no. 2 (1996): 2627–35. http://dx.doi.org/10.1016/s0082-0784(96)80097-x.

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French, C. C. J. "Alternative Engines—Curiosities or Competitors?" Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power Engineering 203, no. 2 (1989): 79–96. http://dx.doi.org/10.1243/pime_proc_1989_203_012_02.

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This paper describes different types of engine used for transportation purposes. Some of the more interesting developments in spark ignition and diesel engines are outlined, but the paper is mainly a review of some of the alternative power plants that have been studied over the past 40 years. These include vapour cycle engines, free-piston engines, compound engines, Stirling engines, gas turbines, stratified charge engines, the catalytic engine, rotary engines and two-stroke spark ignition engines. The paper concludes by discussing possible future developments for some of these alternative engines.

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Che, Xian Da, Ying Ai Jin, Yun Long Xing, and Qing Gao. "Research on the Stratified Charge Control of the Nitrogen-Enriched Intake Air." Applied Mechanics and Materials 328 (June 2013): 1021–25. http://dx.doi.org/10.4028/www.scientific.net/amm.328.1021.

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Nitrogen-enriched intake air (NEA) can reduce the formation of NOx by inhibiting the combustion temperature in cylinder. This paper discusses the research progress on engines using NEA. The result indicates that nitrogen-enriched air can reduce engine NOx emissions remarkably. Besides, this paper analyzes the basic characteristics of the stratified charge control of the nitrogen-enriched intake air. In order to optimize the nitrogen stratification charge, a new nitrogen direct injection engine of stratified charge has been designed.

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Raine, R. R., L. Wyszynski, and R. Stone. "Modelling of NO emissions from homogeneous and stratified charge spark ignition engines." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 216, no. 5 (2002): 403–12. http://dx.doi.org/10.1243/0954407021529219.

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The basis for modelling NO formation in spark ignition (SI) engines by the so-called thermal mechanism is reviewed, along with a comparison of the coefficients that have been recommended for use in the rate equations over the last 25 years. The importance of considering heat transfer, and a multizone representation of the burned gas, is demonstrated by reference to modelling NO in a homogeneous charge SI engine. The model has then been extended to a stratified charge SI engine, in order to investigate the influence of overall equivalence ratio and degree of stratification on the NO emissions and the engine brake specific fuel consumption. For fixed throttle operation, it is concluded that the best trade-off is with an overall weak mixture that is close to homogeneous. For maximum power output using a slightly rich stoichiometric mixture, the mixture should also be close to homogeneous. However, if the engine is constrained to operate with an overall stoichiometric mixture, then the trade-off between NO emissions and brake specific fuel consumption is with a stratified mixture that is rich at the spark plug.

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Fansler, Todd D., David L. Reuss, Volker Sick, and Rainer N. Dahms. "Invited Review: Combustion instability in spray-guided stratified-charge engines: A review." International Journal of Engine Research 16, no. 3 (2015): 260–305. http://dx.doi.org/10.1177/1468087414565675.

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Kono, S. "Study of the stratified charge and stable combustion in DI gasoline engines." JSAE Review 16, no. 4 (1995): 363–68. http://dx.doi.org/10.1016/0389-4304(95)00032-3.

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Itoh, Teruyuki, Akihiko Kakuho, Koji Hiraya, Eiji Takahashi, and Tomonori Urushihara. "Quantitative Analysis of Mixture Preparation Processes in New Direct-Injection Spark Ignition Engines(S.I. Engines, Stratified-Charge Combustion)." Proceedings of the International symposium on diagnostics and modeling of combustion in internal combustion engines 2004.6 (2004): 513–19. http://dx.doi.org/10.1299/jmsesdm.2004.6.513.

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Lee, Yong-Pyo, Sung-Soo Kim, and Sangmin Choi. "A STUDY OF TWO-PHASE INJECTOR PERFORMANCE FOR DIRECT-INJECTION STRATIFIED-CHARGE ENGINES." Atomization and Sprays 8, no. 2 (1998): 199–215. http://dx.doi.org/10.1615/atomizspr.v8.i2.40.

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Viggiano, Annarita, and Vinicio Magi. "Dynamic Adaptive Chemistry applied to homogeneous and partially stratified charge CI ethanol engines." Applied Energy 113 (January 2014): 848–63. http://dx.doi.org/10.1016/j.apenergy.2013.08.002.

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Li, B.-Z., S.-H. Liu, J.-J. Nong, Y.-F. Gong, and L.-B. Zhou. "Development of a direct-injection stratified-charge methanol engine." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 222, no. 11 (2008): 2121–29. http://dx.doi.org/10.1243/09544070jauto905.

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On the basis of the wall-guided, spray-guided, and air-guided technologies related to gasoline direct-injection spark-ignition (DISI) engines, a complex-guided stratified-charge combustion system for a methanol DISI engine was developed. The test engine was a retrofitted four-cylinder diesel engine. The key parameters were optimized numerically and experimentally, such as the location of the swirl deflector, the spatial location of spray, the swirl ratio, the injection and ignition timings, and the needle valve opening pressure. The results show that the direct-injection stratified-charge (DISC) methanol engine can work with an excessive air ratio λ as high as 2.23, and its brake thermal efficiency reaches 29.7 per cent at a speed of 1500r/min, and a brake mean effective pressure of 0.45MPa. The DISC methanol engine exhibits relatively good performance with little cyclic variations, although it is sensitive to induction swirl. The test results indicate that the matching principle is successful. The developed DISC methanol engine can run under variable induction swirl to meet the requirement of stratification combustion under different engine speed operating conditions.

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NOUR, HAMDY M. "THE ENERGY CONSUMPTIONS AND ENVIRONMENTAL POLLUTION OF STRATIFIED CHARGE AND CONVENTIONAL SPARK IGNITION ENGINES." Misr Journal of Agricultural Engineering 26, no. 3 (2009): 1138–54. http://dx.doi.org/10.21608/mjae.2009.107762.

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Li, T., K. Nishida, Y. Zhang, and H. Hiroyasu. "Effect of split injection on stratified charge formation of direct injection spark ignition engines." International Journal of Engine Research 8, no. 2 (2007): 205–19. http://dx.doi.org/10.1243/14680874jer02106.

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Zhao, H., P. Calnan, N. Ladommatos, and T. Ma. "Development of an engine simulation program and its application to stratified charge SI engines." International Journal of Vehicle Design 22, no. 3/4 (1999): 159. http://dx.doi.org/10.1504/ijvd.1999.001864.

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LI, Tie, Keiya NISHIDA, Yuyin ZHANG, Tuyoshi ONOE, and Hiroyuki HIROYAU. "Enhancement of Stratified Charge for DISI Engines through Split Injection(Effect and Its Mechanism)." JSME International Journal Series B 48, no. 4 (2005): 687–94. http://dx.doi.org/10.1299/jsmeb.48.687.

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Kono, S. "Development of a Stratified Charge and Stable Combustion Method in Direct Injection Gasoline Engines." JSAE Review 16, no. 1 (1995): 96. http://dx.doi.org/10.1016/0389-4304(95)94701-n.

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Pal, Pinaki, SeungHwan Keum, and Hong G. Im. "Assessment of flamelet versus multi-zone combustion modeling approaches for stratified-charge compression ignition engines." International Journal of Engine Research 17, no. 3 (2015): 280–90. http://dx.doi.org/10.1177/1468087415571006.

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Cordiner, Stefano, Giovanna de Simone, and Vincenzo Mulone. "Experimental-Numerical Analysis of Nitric Oxide Formation in Partially Stratified Charge (PSC) Natural Gas Engines." SAE International Journal of Engines 2, no. 2 (2009): 326–40. http://dx.doi.org/10.4271/2009-01-2783.

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Fansler, T. D., M. C. Drake, B. Stojkovic, and M. E. Rosalik. "Local fuel concentration, ignition and combustion in a stratified charge spark combustion in a stratified charge spark ignited direct injection engine: Spectroscopic, imaging and pressure-based measurements." International Journal of Engine Research 4, no. 2 (2003): 61–86. http://dx.doi.org/10.1243/146808703321533240.

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A recently developed spark emission spec-troscopy technique has been used to measure the effects of fuel injection timing, spark timing and intake swirl level on the individual-cycle fuel concentration at the spark gap in a wall-guided spark ignited direct injection (SIDI) engine. The fuel-concentration measurements were made simultaneously with measurements of individual-cycle spark discharge energy and cylinder pressure. Endoscopic imaging of the fuel spray and high-speed imaging of combustion (both broadband and spectrally resolved) augment these quantitative data. For optimum engine operation, the fuel-air equivalence ratio at the spark gap just after spark breakdown is rich on average (〈φ〉 ≈1.4–1.5) and varies widely from cycle to cycle (∼25 per cent). The evolution with crank angle of the mean equivalence ratio and its cycle-to-cycle fluctuations are correlated with the cylinder pressure, heat release and imaging data to provide insights into fuel transport and mixture preparation that are important to understanding and optimizing ignition and combustion in SIDI engines. For example, causes of misfires and partial burns have been determined.

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Krisman, Alex, Evatt R. Hawkes, Sanghoon Kook, Magnus Sjöberg, and John E. Dec. "On the potential of ethanol fuel stratification to extend the high load limit in stratified-charge compression-ignition engines." Fuel 99 (September 2012): 45–54. http://dx.doi.org/10.1016/j.fuel.2012.04.001.

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Adomeit, P., O. Lang, and S. Pischinger. "Spray propagation and mixture formation in an air guided direct injection gasoline engine." International Journal of Engine Research 1, no. 2 (2000): 163–70. http://dx.doi.org/10.1243/1468087001545119.

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Numerical analysis is used to gain information on the spray propagation and mixture formation in tumble guided gasoline direct injection (DI) engines. In order to achieve reliable predictions an atomization model for high-pressure swirl injectors is described and verified by comparison to experimental data. The approach is capable of adequately predicting the most important effects, such as nozzle orifice diameter, cone angle or injection pressure on spray development. Furthermore, it is found that the pre-jet generated at the beginning of the injection strongly affects the overall spray development. The temporal development of the pre-jet is described empirically. The in-cylinder computational fluid dynamics (CFD) analysis reveals that the tumble charge motion strongly affects spray propagation and mixture formation in the stratified operation mode, as it transports the fuel vapour cloud towards the spark plug. The CFD simulation improves understanding of the interaction between the flow field, spray propagation and evaporation and enables guidance of the optimization of the flow control and of the injection parameters for tumble guided gasoline DI engines.

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Kim, Dong-Jun, and Kyuho Sim. "Linear Dynamic Analysis of Free-Piston Stirling Engines on Operable Charge Pressure and Working Frequency along with Experimental Verifications." Applied Sciences 11, no. 11 (2021): 5205. http://dx.doi.org/10.3390/app11115205.

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This paper presents a linear dynamic analysis on operable charge pressure and working frequency of free-piston Stirling engines (FPSE) along with experimental verifications. The equations of motion of the FPSE are formulated as a 2-degree-of-freedom (DOF) vibration system of the power piston (PP) and displacer piston (DP), based on the state equation of ideal gas and the isothermal Stirling cycle model. The dynamic models of FPSE we considered are the 1-DOF simple vibration model of each piston and the 2-DOF root locus model of coupled pistons. We developed a test FPSE for verification of the dynamic models and conducted a series of experiments to measure the dynamic behaviors of PP and DP under varying charge pressures for various masses and stiffnesses of the PP. As a result, both prediction models showed good agreements with experimental results. The 1-DOF vibration model was found to be simple and effective for predicting the operating frequency and charge pressure of FPSE. The root locus method showed reasonable predictions with an operation criterion of the PP–DP phase angle of 90°. In addition, the FPSE was confirmed to operate in resonant oscillations when the DP–PP phase angle is 90°, based on analysis of the force vector diagram of the two pistons.

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Snyder, W. E., M. R. Wright, and S. G. Dexter. "A Natural Gas Engine Combustion Rig With High-Speed Photography." Journal of Engineering for Gas Turbines and Power 110, no. 3 (1988): 334–42. http://dx.doi.org/10.1115/1.3240126.

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Engines today must satisfy stringent emission requirements but must at the same time have low fuel consumption. One method of approaching both of these goals in spark-ignited natural gas engines is with lean combustion. The use of as much as 80 percent excess air significantly reduces the peak combustion temperature and, as compared to a stoichiometric engine, reduces the NOx emissions by up to 90 percent and the fuel consumption by up to 15 percent. One limitation on lean combustion, however, is the high energy needed for ignition. In larger engines, a small prechamber containing an easily ignitable near-stoichiometric mixture has proved to be both successful and popular as one method of producing the necessary high ignition energy. Although this form of stratified charge combustion has been known for many years, its development has largely been the result of “cut and try” procedures. Lack of access for suitable instrumentation, combined with the difficulty of isolating the individual variables which affect performance, has limited the fundamental understanding of the mechanism of prechamber combustion. This paper summarizes results from a research program where a constant-volume combustion rig is used to simulate engine operation. Emphasis is placed on high-speed photography of the prechamber combustion. A second program on a single-cylinder prechamber spark-ignited gas engine and a third on a multiple-cylinder engine will be reported in subsequent papers.

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Rotondi, Rossella. "Modeling Mixture Formation in a Gasoline Direct Injection Engine." Journal of Applied Mechanics 73, no. 6 (2005): 931–39. http://dx.doi.org/10.1115/1.2173284.

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Mixture formation and combustion in a gasoline direct injection (GDI) engine were studied. A swirl-type nozzle, with an inwardly opening pintle, was used to inject the fuel directly in a four stroke, four cylinder, four valves per cylinder engine. The atomization of the hollow cone fuel spray was modeled by using a hybrid approach. The most important obstacle in the development of GDI engines is that the control of the stratified-charge combustion over the entire operating range is very difficult. Since the location of the ignition source is fixed in SI engines the mixture cloud must be controlled both temporally and spatially for a wide range of operating conditions. Results show that the volume of the spark must be considered when discretizing the computational domain because it highly influences the flow field in the combustion chamber. This is because the volume occupied by the plug cannot be neglected since it is much bigger than the ones used in port fuel injection engines. The development of a successful combustion system depends on the design of the fuel injection system and the matching with the in-cylinder flow field: the stratification at part load appears to be the most crucial and critical step, and if the air motion is not well coupled with the fuel spray it would lead to an increase of unburned hydrocarbon emission and fuel consumption

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Kakaee, Amir Hasan, Behrooz Mashadi, and Mostafa Ghajar. "A novel volumetric efficiency model for spark ignition engines equipped with variable valve timing and variable valve lift Part 1: model development." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, no. 2 (2016): 175–91. http://dx.doi.org/10.1177/0954407016650545.

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Estimation of the air charge and the volumetric efficiency is one of the most challenging tasks in the control of internal-combustion engines owing to the intrinsic complexity and the non-linearity of the gas flow phenomena. In particular, with emerging new technologies such as systems with variable valve timing and variable valve lift, the number of effective parameters increases greatly, making the estimation task more complicated. On the other hand, using a three-way catalyst converter needs strict control of the air-to-fuel ratio to around the stoichiometric ratio, and hence more accurate models are required for estimation of the air charge. Therefore, various models have been proposed in the literature for estimation of the volumetric efficiency and the air charge. However, they are either strictly based on physical first principles, making them impractical for conventional applications, or nearly fully empirical and need many experimental data for calibration. In this paper, using a novel approach, a new semiempirical model is proposed for estimation of the volumetric efficiency, which is calibrated with very few experimental data and can be used easily for real-time applications. In addition to the valve timings, the engine speed and the intake manifold pressure, the inlet valve lift is also considered as the model input. The generalizability of the model is proved by applying it to estimate the volumetric efficiency of six different engines. Furthermore, a systematic approach is taken to simplify the proposed model and to strengthen its prediction capability. The result is a simple, practical and generalizable model which can be used for various spark ignition engines, can be trained with very few data and can be utilized for estimating accurately the volumetric efficiency in real-time applications.

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Winklhofer, E., G. K. Fraidl, and A. Plimon. "Monitoring of Gasoline Fuel Distribution in a Research Engine." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 206, no. 2 (1992): 107–15. http://dx.doi.org/10.1243/pime_proc_1992_206_166_02.

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Fuel distribution in gasoline engines has significant influence on the cyclic stability of charge ignition and combustion, and hence on engine performance parameters related to the variation of combustion and heat release. There are numerous ways to influence in-cylinder fuel distribution by means of mixture preparation systems, engine aspiration or by combustion chamber geometry itself. However, methods to observe in-cylinder fuel distribution are scarce, and very often charge distribution—homogeneous or highly stratified—is just heuristically assessed, based on engine performance data. Therefore, a method has been devised which allows observation of vaporized fuel in the cylinders of optically accessed engines. The method, based on the absorption of infra-red laser light radiation by hydrocarbon molecules, needs optical access to the combustion chamber to transmit a laser beam of appropriate wavelength and to monitor the attenuation caused by absorption and scattering. The paper describes the concept of the measurement technique and its application to an optically accessed single-cylinder research engine. The engine is equipped with a transparent cylinder liner to allow investigation of the entire cylinder volume. In order to evaluate the feasibility of the method, the response of the line-of-sight absorption measurements to various engine operating modes was investigated. A comparison with actual engine data showed that fuel distribution, as governed by the injector operating mode, can have significant influence on combustion and cycle-to-cycle stability.

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Hunicz, Jacek, Maciej Mikulski, and Henryk Komsta. "HCCI combustion control using advanced gasoline direct injection techniques." MATEC Web of Conferences 234 (2018): 03003. http://dx.doi.org/10.1051/matecconf/201823403003.

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Homogeneous Charge Compression Ignition (HCCI) is a promising low temperature combustion technology for reciprocating engines that offers high fuel efficiency and extremely low exhaust emissions. However, combustion control should be improved and operating range should be widened for the technology to achieve production level. In this study an overview of different direct gasoline injection control approaches, applied to improve stability at low engine loads and to reduce pressure rise rates at high load regime, is presented. The tests are performed on a single-cylinder research engine operated in a negative valve overlap (NVO) mode for residual gasses trapping. The investigated direct injection schemes included: (i) fuel injection during the NVO period to improve mixture reactivity and take an advantage of exhaust-fuel reactions thermal effects, (ii) fuel injection during intake stroke to create homogeneous charge and (iii) late fuel injection during compression stroke to create stratified charge. The results showed that application of early NVO injection enables active control of combustion timing at nearly idle conditions. The late fuel injection, during the compression stroke, enabled mitigation of excessive pressure rise rates at high engine load regime.

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Li, J., Y. Huang, T. F. Alger, et al. "Liquid Fuel Impingement on In-Cylinder Surfaces as a Source of Hydrocarbon Emissions From Direct Injection Gasoline Engines." Journal of Engineering for Gas Turbines and Power 123, no. 3 (2000): 659–68. http://dx.doi.org/10.1115/1.1370398.

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Hydrocarbon (HC) emissions from direct injection gasoline (DIG) engines are significantly higher than those from comparable port fuel injected engines, especially when “late” direct injection (injection during the compression stroke) is used to produce a fuel economy benefit via unthrottled lean operation. The sources of engine-out hydrocarbon emissions for late direct injection are bulk flame quench, low temperatures for post-combustion oxidation, and fuel impingement on in-cylinder walls. An experimental technique has been developed that isolates the wall impingement source from the other sources of HC emissions from DIG engines. A series of steady-state and transient experiments is reported for which the HC emissions due to operation with a premixed charge using a gaseous fuel are compared to those when a small amount of liquid fuel is injected onto an in-cylinder surface and the gaseous fuel flow rate is decreased correspondingly. The steady-state experiments show that wetting any in-cylinder surface dramatically increases HC emissions compared to homogeneous charge operation with a gaseous fuel. The results of the transient fuel injection interrupt tests indicate that liquid-phase gasoline can survive within the cylinder of a fully warmed-up firing engine and that liquid fuel vaporization is slower than current computational models predict. This work supports the argument that HC emissions from DIG engines can be decreased by reducing the amount of liquid fuel that impinges on the cylinder liner and piston, and by improving the vaporization rate of the fuel that is deposited on these surfaces.

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Roark, Jennifer, Kelly E. Knight, Heather Olson, and Heidi DeSandre. "Predictors of Child Abuse Charges Within the Context of Domestic Violence Arrests." Crime & Delinquency 63, no. 13 (2016): 1777–803. http://dx.doi.org/10.1177/0011128716661141.

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This article investigates how different factors of a domestic violence incident impact the likelihood of a child abuse charge within the context of domestic violence arrests. Data from 5,148 domestic violence arrests were used to test whether domestic violence-, incident-, and child-based predictors increased the likelihood of a child abuse charge. Logistic regression models of gender-stratified samples were employed to test for gender differences among domestic violence arrestees. The results demonstrated predictors affected men’s odds of a child abuse charge when compared with women. For men and women, children witnessing the domestic violence incident had the largest impact on a child abuse charge. These results contribute to the underdeveloped area of police response to child abuse in domestic violence cases.

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Chehroudi, B., P. Lombardi, P. G. Felton, and F. V. Bracco. "Spray Photographs, Poppet Lift, and Injection Pressure of an Oscillating Poppet Injector." Journal of Fluids Engineering 109, no. 3 (1987): 289–96. http://dx.doi.org/10.1115/1.3242663.

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Sprays from an injector with a conical oscillating poppet and supplied with fuel at injection rates similar to those used in direct-injection stratified-charge engines have been characterized. Instantaneous injection pressure and poppet lift were measured and short-exposure backlit photographs were taken at several times during injection. Spray axial tip penetration and velocity were determined from the photographs. The experiments were conducted in a constant-volume pressure vessel. The gas was nitrogen and the liquid was hexane. The gas temperature was either 25° or 55°C. The experiments included a systematic variation of the ambient pressure, pump speed and injected liquid volume. It was found that the structure of the spray was strongly affected by the chamber pressure. The hollow cone collapsed and injection duration, spray axial initial velocity and tip penetration decreased with increasing chamber pressure. Increasing pump speed decreased both injection duration and number of oscillations.

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Itoh, T., A. Kakuho, K. Hiraya, E. Takahashi, and T. Urushihara. "A study of mixture formation processes in direct injection stratified charge gasoline engines by quantitative laser-induced fluorescence imaging and the infrared absorption method." International Journal of Engine Research 7, no. 5 (2006): 423–34. http://dx.doi.org/10.1243/14680874jer04705.

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Allocca, L., L. Andreassi, and S. Ubertini. "Enhanced Splash Models for High Pressure Diesel Spray." Journal of Engineering for Gas Turbines and Power 129, no. 2 (2006): 609–21. http://dx.doi.org/10.1115/1.2432891.

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Mixture preparation is a crucial aspect for the correct operation of modern direct injection (DI) Diesel engines as it greatly influences and alters the combustion process and, therefore, the exhaust emissions. The complete comprehension of the spray impingement phenomenon is a quite complete task and a mixed numerical-experimental approach has to be considered. On the modeling side, several studies can be found in the scientific literature but only in the last years complete multidimensional modeling has been developed and applied to engine simulations. Among the models available in literature, in this paper, the models by Bai and Gosman (Bai, C., and Gosman, A. D., 1995, SAE Technical Paper No. 950283) and by Lee et al. (Lee, S., and Ryou, H., 2000, Proceedings of the Eighth International Conference on Liquid Atomization and Spray Systems, Pasadena, CA, pp. 586–593; Lee, S., Ko, G. H., Ryas, H., and Hong, K. B., 2001, KSME Int. J., 15(7), pp. 951–961) have been selected and implemented in the KIVA-3V code. On the experimental side, the behavior of a Diesel impinging spray emerging from a common rail injection system (injection pressures of 80 and 120MPa) has been analyzed. The impinging spray has been lightened by a pulsed laser sheet generated from the second harmonic of a Nd-yttrium-aluminum-garnet laser. The images have been acquired by a charge coupled device camera at different times from the start of injection. Digital image processing software has enabled to extract the characteristic parameters of the impinging spray with respect to different operating conditions. The comparison of numerical and experimental data shows that both models should be modified in order to allow a proper simulation of the splash phenomena in modern Diesel engines. Then the numerical data in terms of radial growth, height and shape of the splash cloud, as predicted by modified versions of the models are compared to the experimental ones. Differences among the models are highlighted and discussed.

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Arashi, Daiki, Yuuto Kakinuma, Kei Sugiura, Takamasa Terai, Satoshi Ashizawa, and Takeo Oomichi. "Research on High Efficiency Operation Method of Linear Generator Engine." Journal of Robotics and Mechatronics 30, no. 1 (2018): 93–105. http://dx.doi.org/10.20965/jrm.2018.p0093.

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In this paper, a novel generator engine designed to achieve high efficiency, which we call an internal combustion engine with linear generator (ICELG), is proposed and its feasibility and validity are demonstrated using a simulator. Unlike conventional crank-type engines, the ICELG employs a linear motor, which is directly connected to the piston-cylinder unit, instead of a crank mechanism, thus eliminating the motional constraints. This allows the stroke to be changed in mid-operation. The simulator is based on a model of the DC motor and consists of the motor model, which combines the actuator and generator, the engine model, which computes the state changes in the cylinder, and the charge/discharge model, which computes the energy charge and discharge. The ICELG’s feasibility is evaluated by determining the energy losses and charge in the respective models. It is possible to extract a greater amount of energy in the combustion stroke by lengthening the stroke. Losses can be reduced during the intake and exhaust strokes by operating at low speed in order to prevent drastic pressure changes in the cylinder. During the compression stroke, the inertial energy is stored when the pressure in the cylinder is still low, and then subsequently released as inertial force beyond the position from which it can complete the combustion stroke, as a result of which the motor resistance loss is reduced. It was found that the ICELG achieves higher efficiency than conventional generator engines when operated in this manner.

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Tran, Luc-Sy, Yuyang Li, Meirong Zeng, et al. "Elevated pressure low-temperature oxidation of linear five-heavy-atom fuels: diethyl ether, n-pentane, and their mixture." Zeitschrift für Physikalische Chemie 234, no. 7-9 (2020): 1269–93. http://dx.doi.org/10.1515/zpch-2020-1613.

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AbstractDiethyl ether (DEE) has been proposed as a biofuel additive for compression-ignition engines, as an ignition improver for homogeneous charge compression ignition (HCCI) engines, and as a suitable component for dual-fuel mixtures in reactivity-controlled compression ignition (RCCI) engines. The combustion in these engines is significantly controlled by low-temperature (LT) chemistry. Fundamental studies of DEE LT oxidation chemistry and of its influence in fuel-mixture oxidation are thus highly important, especially at elevated pressures. Elevated pressure speciation data were measured for the LT oxidation of DEE, of its similarly-structured linear five-heavy-atom hydrocarbon fuel (n-pentane), and of a mixture of the two fuels in a jet-stirred reactor (JSR) in the temperature range of 400–1100 K and at various pressures up to 10 bar. The pressure influence on the LT oxidation chemistry of DEE was investigated by a comparison of the measured profiles of oxidation products. The results for DEE and n-pentane were then inspected with regard to fuel structure influences on the LT oxidation behavior. The new speciation data were used to test recent kinetic models for these fuels [Tran et al., Proc. Combust. Inst. 37 (2019) 511 and Bugler et al., Proc. Combust. Inst. 36 (2017) 441]. The models predict the major features of the LT chemistry of these fuels well and could thus subsequently assist in the data interpretation. Finally, the LT oxidation behavior of an equimolar mixture of the two fuels was explored. The interaction between the two fuels and the effects of the pressure on the fuel mixture oxidation were examined. In addition to reactions within the combined model for the two fuels, about 80 cross-reactions between primary reactive species generated from these two fuel molecules were added to explore their potential influences.

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Belkebir, Saliha Mohammed, Benyoucef Khelidj, and Miloud Tahar Abbes. "Effects of EGR and Alternative Fuels on Homogeneous Charge Compression Ignition (HCCI) Combustion Mode." International Journal of Design & Nature and Ecodynamics 16, no. 2 (2021): 135–44. http://dx.doi.org/10.18280/ijdne.160203.

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We present in this article an analysis of the impacts of the exhaust gas recirculation (EGR) and alternative fuels on HCCI combustion mode. The objective is to reduce the pollutant emissions below the levels of established pollution standards. The ANSYS CHEMKIN-Pro software and the combined chemical kinetics mechanism were used to perform simulations for a closed homogeneous reactor under conditions relevant to HCCI engines. The calculation process is based on one single-zone in the combustion chamber. Numerical simulation has proven the ability of the models adopted, which use the essential mechanisms of the fuel combustion process, to reproduce, among other things, the evolution of the formation of chemical species. This study showed that adding hydrogen (H2) to methane (CH4) is an interesting alternative fuel because it reduces ignition time. It was concluded that an increase of EGR rate conducts to a slower combustion process, lower temperatures, and the reduction of nitrogen oxide (NOX) emissions.

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Kaiser, E. W., J. Yang, T. Culp, N. Xu, and M. M. Maricq. "Homogeneous charge compression ignition engine-out emission-does flame propagation occur in homogeneous charge compression ignition?" International Journal of Engine Research 3, no. 4 (2002): 185–95. http://dx.doi.org/10.1243/146808702762230897.

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Engine-out emissions data [CO, CO2, speciated hydrocarbons (HC), and particulate matter (size and number density)] were obtained from a single-cylinder, 660 cm3, homogeneous charge compression ignition (HCCI) engine operated on gasoline fuel using direct in-cylinder injection. Data were taken as functions of the air-fuel ratio (A/F) (30–270), r/min, inlet air temperature and fuel injection timing. Three important observations were made A sharp break occurs in the CO and CO2 emissions indices beginning near A/F = 75. Above A/F ∼ 100, CO is the primary carbon oxide while for A/F < 70, CO2 is the major carbon oxide. The HC emissions index increases linearly, beginning near A/F ∼ 30:1. Below this A/F, the HC index is characteristic of crevice emissions (∼ 3.5 per cent). These results do not prove this unequivocally, but can be explained by a mechanism in which, for A/F < 75, flame propagation occurs over relatively short distances between the multiple autoignition sites within the combustion chamber. Adiabatic compression calculations indicate that for A/F < 75, the compression temperature (∼ 1150 K) is sufficiently high to support flame propagation. The linear increase in HC emissions above that expected from crevice storage can be explained by noting that autoignition becomes more difficult as the A/F becomes leaner and fewer ignition sites are likely to exist within the combustion chamber, reducing the amount of fuel combusted. Conventional models of HCCI combustion involving multi-zone autoignition may also explain the data, but the above concept is an alternative combustion mechanism for HCCI, which should be considered. Particulate emissions at moderate load from this HCCI engine, while much lower than from a diesel, are similar to those from early-injection DISI (direct injection spark ignition) engines and should not be assumed to be negligible.

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Kong, S.-C., Y. Ra, and R. D. Reitz. "Performance of multi-dimensional models for simulating diesel premixed charge compression ignition engine combustion using low- and high-pressure injectors." International Journal of Engine Research 6, no. 5 (2005): 475–86. http://dx.doi.org/10.1243/146808705x30567.

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An engine CFD model has been developed to simulate premixed charge compression ignition (PCCI) combustion using detailed chemistry. The numerical model is based on the KIVA code that is modified to use CHEMKIN as the chemistry solver. The model was applied to simulate ignition, combustion, and emissions processes in diesel engines operated to achieve PCCI conditions. Diesel PCCI experiments using both low- and high-pressure injectors were simulated. For the low-pressure injector with early injection (close to intake valve closure), the model shows that wall wetting can be minimized by using a pressure-swirl atomizer with a variable spray angle. In the case of using a high-pressure injector, it is found that late injection (SOI = 5 ° ATDC) benefits soot emissions as a result of low-temperature combustion at highly premixed conditions. The model was also used to validate the emission reduction potential of an HSDI diesel engine using a double injection strategy that favours PCCI conditions. It is concluded that the present model is useful to assess future engine combustion concepts, such as PCCI and low-temperature combustion (LTC).

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Brückner, Clemens, Panagiotis Kyrtatos, and Konstantinos Boulouchos. "NOx emissions in direct injection diesel engines: Part 2: model performance for conventional, prolonged ignition delay, and premixed charge compression ignition operating conditions." International Journal of Engine Research 19, no. 5 (2017): 528–41. http://dx.doi.org/10.1177/1468087417721558.

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Investigations from recent years have shown that at operating conditions characterized by long ignition delays and resulting large proportions of premixed combustion, the NOx emission trend does not correspond to the (usually) postulated correlation with an appropriately defined (adiabatic) burnt flame temperature. This correlation, however, is the cornerstone of most published NOx models for direct injection diesel engines. In this light, a new phenomenological NOx model has been developed in Brückner et al. (Part 1), which considers NOx formation from products of premixed and diffusion combustion and accounts for compression heating of post-flame gases, and describes NOx formation by thermal chemistry. In this study (Part 2), the model is applied to predict NOx emissions from two medium-speed direct injection diesel engines of different size and at various operating conditions. Single parameter variations comprising sweeps of injection pressure, start of injection, load, exhaust gas recirculation rate, number of injections, and end-of-compression temperature are studied on a single-cylinder engine. In addition, different engine configurations (valve timing, turbocharger setup) and injection parameters of a marine diesel engine are investigated. For both engines and all parameter variations, the model prediction shows good agreement. Most notably, the model captures the turning point of the NOx emission trend with increasing ignition delay (first decreasing, then increasing NOx) for both engines. The differentiation in the physical treatment of the products of premixed and diffusion with increasing ignition delay showed to be essential for the model to capture the trend-reversal. Specifically, the model predicted that peak NOx formation rates in diffusion zones decrease with increasing ignition delay, whereas for the same change in ignition delay, peak formation rates in premixed zones increase. This is caused by the high energy release in short time, causing a strong compression of existing premixed combustion product zones that mix at a slower rate and have less time to mix, significantly increasing their temperature. In contrast, the model under-predicts NOx emissions for very low oxygen concentrations, in particular below 15 vol.%, which is attributed to the simple thermal NOx kinetic mechanism used. It is concluded that the new model is able to predict NOx emissions for conventional diesel combustion and for long ignition delay operating conditions, where a substantial amount of heat is released in premixed mode.

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Yan, Yan, and Yu Sheng Zhang. "The Study on PCCI Mode of Diesel Engine Fueled with Methanol/Dimethyl Ether." Applied Mechanics and Materials 607 (July 2014): 629–32. http://dx.doi.org/10.4028/www.scientific.net/amm.607.629.

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Taking into account China's abundant coal resources, methanol and DME(Dimethyl Ether) obtained from coal are good alternative fuels. The research project is to utilize the fuel of DME and methanol in diesel engines for new combustion models PCCI (Premixed Charge Compression Ignition).The tests of the PCCI mode with different boundary conditions were studied on PCCI test bench. PCCI combustion is consisted of three stages: low temperature reaction of DME, high-temperature reaction of DME and diffusion combustion reaction of methanol. DME as combustion improver should be kept relatively low concentration, and with the decrease of methanol, its concentration need to be reduced. Methanol and formaldehyde are important parts of HC emission, their volume fraction was about 70%.

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Kumar, Umesh. "Vlsi Interconnection Modelling Using a Finite Element Approach." Active and Passive Electronic Components 18, no. 3 (1995): 179–202. http://dx.doi.org/10.1155/1995/97362.

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In the last decade, an important shift has taken place in the design of hardware with the advent of smaller and denser integrated circuit packages. Analysis techniques are required to ensure the proper electrical functioning of this hardware. An efficient method is presented to model the parasitic capacitance of VLSI (very large scale integration) interconnections. It is valid for conductors in a stratified medium, which is considered to be a good approximation for theSi−SiO2system of which present day ICs are made. The model approximates the charge density on the conductors as a continuous function on a web of edges. Each base function in the approximation has the form of a “spider” of edges. Here the method used [1] has very low complexity, as compared to other models used previously [2], and achieves a high degree of precision within the range of validity of the stratified medium.

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Harada, Yuji, Kenji Uchida, Tatsuya Tanaka, et al. "Wall heat transfer of unsteady near-wall flow in internal combustion engines." International Journal of Engine Research 20, no. 7 (2019): 817–33. http://dx.doi.org/10.1177/1468087419853432.

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Although the near-wall turbulence is not fully developed in the engine combustion chamber, wall heat transfer models based on flow characteristics in fully developed near-wall turbulence are typically employed in engine simulations to predict heat transfer. Only few studies reported the wall heat transfer mechanism in near-wall flow where the near-wall turbulence was not fully developed as expected in the engine combustion chamber. In this study, the velocity distribution and wall heat flux in such a near-wall flow were evaluated using a rapid compression and expansion machine. In addition to the experimental approach, a numerical simulation with highly resolved calculation mesh was applied in various flow fields expected in the engine combustion chamber. As a result, the turbulent Reynolds number that represents the relationship between turbulent production and dissipation varied in the wall boundary layer according to the near-wall flow condition. This behavior affects the wall heat transfer. Considering this finding, a new model was formulated by introducing a ratio of turbulent Reynolds number in an intended near-wall flow to that in fully developed near-wall turbulence. It was confirmed that the proposed model could improve the prediction accuracy of wall heat flux even in near-wall flow where the near-wall turbulence was not fully developed. By applying the proposed model in engine computational fluid dynamics, it was found that the proposed model could predict the wall heat flux in a homogeneous charge compression ignition gasoline engine with acceptable accuracy.

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