subject:(Air Assisted Injection)

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Loughborough University

1. Das, Sudhakar. Computational fluid dynamic modelling of flow and combustion in spark ignition engines.

Degree: PhD, 1996, Loughborough University

The present work is based on the need for understanding the in-cylinder flow and its subsequent effects on combustion in a valved-two-stroke spark ignition engine with fuel injection using Computational Fluid Dynamics (CFD) and experimental techniques. In this context, the CFD code KIVA-II has been modified to model the two-stroke engine gas exchange and combustion processes. A 3-D Cartesian grid generation program for complex engine geometry has been added to the KIVA code which has been modified to include intake and exhaust flow processes with valves. New and improved sub models for wall jet interaction, mixing controlled combustion and one dimensional wave action have also been incorporated. The modified version of the program has been used to simulate a fuel injected two-stroke spark ignition engine and parametric studies have been undertaken. The simulated flow, combustion and exhaust emission characteristics over a wide range of operating conditions show the expected trends in behaviour observed in actual engines. In the second phase of this study, the air-assisted-fuel-injection (AAFI) process into a cylinder has been simulated with a high resolution computational grid. The simulation results are presented and compared with experimental data obtained using the Schlieren optical technique. An approximate method based on the conservation of mass, momentum and energy of the spray jet and using a comparatively coarse grid has been suggested for simulating the AAFI process. The simulation study predicts a high degree of atomisation of fuel spray with Sauter mean diameter around 10 μm even with moderate air and fuel pressures. The penetration and width of spray are simulated within 15% of the experimental values. In the last phase of this study, the flow and combustion processes have been studied for a four-stroke spark ignition engine with the AAFI process. The simulation results obtained using this approximate method have been validated with experimental data generated for the same engine configuration.

Subjects/Keywords: 532; Air-assisted-fuel injection; Exhaust emissions

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APA (6^th Edition):

Das, S. (1996). Computational fluid dynamic modelling of flow and combustion in spark ignition engines. (Doctoral Dissertation). Loughborough University. Retrieved from http://hdl.handle.net/2134/7327

Chicago Manual of Style (16^th Edition):

Das, Sudhakar. “Computational fluid dynamic modelling of flow and combustion in spark ignition engines.” 1996. Doctoral Dissertation, Loughborough University. Accessed February 28, 2021. http://hdl.handle.net/2134/7327.

MLA Handbook (7^th Edition):

Das, Sudhakar. “Computational fluid dynamic modelling of flow and combustion in spark ignition engines.” 1996. Web. 28 Feb 2021.

Vancouver:

Das S. Computational fluid dynamic modelling of flow and combustion in spark ignition engines. [Internet] [Doctoral dissertation]. Loughborough University; 1996. [cited 2021 Feb 28]. Available from: http://hdl.handle.net/2134/7327.

Council of Science Editors:

Das S. Computational fluid dynamic modelling of flow and combustion in spark ignition engines. [Doctoral Dissertation]. Loughborough University; 1996. Available from: http://hdl.handle.net/2134/7327

Indian Institute of Science

2. Pandey, Sunil Kumar. Exploration And Assessment of HCCI Strategies for a Multi-Cylinder Heavy-Duty Diesel Engine.

Degree: PhD, Faculty of Engineering, 2017, Indian Institute of Science

URL: http://etd.iisc.ac.in/handle/2005/2720

Homogeneous Charge Compression Ignition (HCCI) combustion is an alternative combustion mode in which the fuel is homogeneously mixed with air and is auto-ignited by compression. Due to charge homogeneity, this mode is characterized by low equivalence ratios and temperatures giving simultaneously low nitric oxide (NOx) and soot in diesel engines. The conventional problem of NOx-soot trade-off is avoided in this mode due to absence of diffusion combustion. This mode can be employed at part load conditions while maintaining conventional combustion at high load thus minimizing regulatory cycle emissions and reducing cost of after-treatment systems. The present study focuses on achieving this mode in a turbocharged, common rail, direct injection, four-cylinder, heavy duty diesel engine. Specifically, the work involves a combination of three-dimensional CFD simulations and experiments on this engine to assess both traditional and novel strategies related to fuel injection. The first phase of the work involved a quasi-dimensional simulation of the engine to assess potential of achieving HCCI. This was done using a zero-dimensional, single-zone HCCI combustion model with n-heptane skeletal chemistry along with a one-dimensional model of intake and exhaust systems. The feasibility of operation with realistic knock values with high EGR rate of 60% was observed. The second aspect of the work involved three-dimensional CFD simulations of the in-cylinder process with wall film prediction to evaluate injection strategies associated with Early Direct Injection (EDI). The extended Coherent Flame Model-3Zone (ECFM-3Z) was employed for combustion simulation of conventional CI and EDI, and was validated with experimental in-cylinder pressure data from the engine. A new Uniformity Index (UI) parameter was defined to assess charge homogeneity. Results showed significant in-homogeneity and presence of wall film for EDI. Simulations were conducted to assess improvement of charge homogeneity by several strategies; narrow spray cone angle, injection timing, multiple injections, intake air heating, Port Fuel Injection (PFI) as well as combination of PFI and EDI. The maximum UI achieved by EDI was 0.78. The PFI strategy could achieve UI of 0.95; however, up to 50% of fuel remained trapped in the port after valve closure. This indicated that except EDI, none of the above-mentioned strategies could help achieve the benefits of the HCCI mode. The third part of the work involved engine experimentation to assess the EDI strategy. This strategy produced lower soot than that of conventional CI combustion with very short combustion duration, but led to high knock and NOx which is attributed to pool fire burning phenomenon of the wall film, as confirmed by CFD. An Optimized EDI (OptimEDI) strategy was then developed based on results of CFD and Design of Experiments. The Optim EDI consisted of triple injections with split ratio of 41%-45%-14% and advancing the first injection. This strategy gave 20% NOx and soot reduction over the conventional CI… Advisors/Committee Members: Ravikrishna, R V (advisor).

Subjects/Keywords: Homogeneous Charge Compression Ignition Engines (HCCI); Low Temperature Combustion; Multi-Cylinder Heavy-Duty Diesel Engines; Diesel Motor; Diesel Engines; Early Direct Injection; Air-Assisted Injection; Combustion; Diesel Homogeneous Charge Compression Ignition; Diesel Fuels; Diesel-Fueled Engines; Fuel Injection; Internal Combustion Engines; Computational Fluid Dynamics; Mechanical Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Pandey, S. K. (2017). Exploration And Assessment of HCCI Strategies for a Multi-Cylinder Heavy-Duty Diesel Engine. (Doctoral Dissertation). Indian Institute of Science. Retrieved from http://etd.iisc.ac.in/handle/2005/2720

Chicago Manual of Style (16^th Edition):

Pandey, Sunil Kumar. “Exploration And Assessment of HCCI Strategies for a Multi-Cylinder Heavy-Duty Diesel Engine.” 2017. Doctoral Dissertation, Indian Institute of Science. Accessed February 28, 2021. http://etd.iisc.ac.in/handle/2005/2720.

MLA Handbook (7^th Edition):

Pandey, Sunil Kumar. “Exploration And Assessment of HCCI Strategies for a Multi-Cylinder Heavy-Duty Diesel Engine.” 2017. Web. 28 Feb 2021.

Vancouver:

Pandey SK. Exploration And Assessment of HCCI Strategies for a Multi-Cylinder Heavy-Duty Diesel Engine. [Internet] [Doctoral dissertation]. Indian Institute of Science; 2017. [cited 2021 Feb 28]. Available from: http://etd.iisc.ac.in/handle/2005/2720.

Council of Science Editors:

Pandey SK. Exploration And Assessment of HCCI Strategies for a Multi-Cylinder Heavy-Duty Diesel Engine. [Doctoral Dissertation]. Indian Institute of Science; 2017. Available from: http://etd.iisc.ac.in/handle/2005/2720

Universitat Politècnica de València

3. Valero Marco, Jorge. Analysis of the potential of SI lean combustion and CAI combustion in a two-stroke spark-assisted gasoline engine .

Degree: 2020, Universitat Politècnica de València

URL: http://hdl.handle.net/10251/138556

[EN] Internal combustion engines are in a situation in which they must be cleaner and more efficient than they have ever been. This change is motivated by the global and continuous evolution of the emissions regulations linked to their commercialization, which try to establish the path to protect the human health, and move towards more sustainable energetic models. Framed in this context, the research work developed in this PhD thesis has focused on the way to continue improving the spark ignition engines. To this end, a prototype two-stroke engine has been used, with the idea of studying the Spark Ignited combustion in lean conditions ('lean SI') and the Controlled Auto-Ignition combustion 'CAI'). In this way, the traditional 'SI' operation in stoichiometric conditions of this type of engines is replaced, looking for an improvement in fuel efficiency, and a reduction, at the same time, of the pollutant emissions. This work has been approached mainly from an experimental point of view. Firstly, different works have been performed on the engine: operation of the different combustion modes, definition of the operating strategies, and compilation of experimental data coming from the engine operation in the different regions of the engine map. And, secondly, all this data has been analyzed and studied in detail to define the strengths and weaknesses of each combustion mode applied to the different engine operating conditions. The combination of these two works has led to obtain a large amount of data about the achievable efficiencies and the emissions values obtained in each combustion mode. And, in addition, the influence on the combustion of the burned gases recirculation in the engine ('EGR'), has also been studied as a strategy to reduce emissions, and control the combustion at high loads in both combustion modes. Regarding the analytical part of the work, several problems have been detected. Firstly, the high combustion variability in this engine, and secondly, the coupling of two completely different combustion modes. These issues have generated the need to analyze the data obtained in a more detailed way, in order to get more information about the combustion process. To solve these two aspects, first, a different point of view has been raised when dealing with the combustion diagnosis, the cycle to cycle analysis, and secondly, a combustion analysis methodology has been proposed in order to allow the combustion analysis from a more detailed point of view. In this way the combustion development is studied, and thus, the differentiation between the different combustion events that take place in the engine can be studied. All this work has been useful to define the strategies to operate the whole engine map by combining the 'lean SI' and 'CAI' combustion modes. This solution, compared to the current Euro VI engines, has presented higher efficiency values complying with the established emissions limits, showing in this way, the high potential of these combustion modes applied to 'SI' engines, as well as a real… Advisors/Committee Members: López Sánchez, José Javier (advisor).

Subjects/Keywords: Two-stoke engine; engines developement; CAI (Controlled Auto-Ignition); SI (Spark Ignition); Lean Combustion; advanced combustion modes; combustion analysis; instantaneous cycles; cycle to cycle variation; air-assisted injection; HRL (Heat Release Law); combustion speed.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Valero Marco, J. (2020). Analysis of the potential of SI lean combustion and CAI combustion in a two-stroke spark-assisted gasoline engine . (Doctoral Dissertation). Universitat Politècnica de València. Retrieved from http://hdl.handle.net/10251/138556

Chicago Manual of Style (16^th Edition):

Valero Marco, Jorge. “Analysis of the potential of SI lean combustion and CAI combustion in a two-stroke spark-assisted gasoline engine .” 2020. Doctoral Dissertation, Universitat Politècnica de València. Accessed February 28, 2021. http://hdl.handle.net/10251/138556.

MLA Handbook (7^th Edition):

Valero Marco, Jorge. “Analysis of the potential of SI lean combustion and CAI combustion in a two-stroke spark-assisted gasoline engine .” 2020. Web. 28 Feb 2021.

Vancouver:

Valero Marco J. Analysis of the potential of SI lean combustion and CAI combustion in a two-stroke spark-assisted gasoline engine . [Internet] [Doctoral dissertation]. Universitat Politècnica de València; 2020. [cited 2021 Feb 28]. Available from: http://hdl.handle.net/10251/138556.

Council of Science Editors:

Valero Marco J. Analysis of the potential of SI lean combustion and CAI combustion in a two-stroke spark-assisted gasoline engine . [Doctoral Dissertation]. Universitat Politècnica de València; 2020. Available from: http://hdl.handle.net/10251/138556

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