Effect of Conical Spray and Multi-Hole Spray on Gasoline Engine Mixture Formation and Combustion Performance Based on Different Injection Strategies

Abstract This article presents a numerical investigation carried out to determine the effects of second and third injection timing on combustion characteristics and mixture formation of a gasoline direct injection (GDI) engine by comparing conical spray against multihole spray. The results showed that at the engine 80% full load of 2000 r/min, the difference in mixture distribution between the two sprays was obvious with double and triple injection strategies. With the second injection timing from 140 deg CA delay to 170 deg CA, the in-cylinder pressure, the in-cylinder temperature, and the heat release rate of the conical spray increased by 20.8%, 9.8%, and 30.7% and that of the multihole spray decreased by 30.7%, 13.6%, and 37.8%. The delay of the injection time reduced the performance of the engine with the multihole spray, and the performance of the multihole spray was obviously in the simulation of the triple injection strategy. However, for the conical spray, the application of the triple injection strategy increased the temperature and the pressure compared with the double injection strategy.

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The Effects of Injection Timing and Injected Fuel Mass on Local Charge Conditions and Emissions for Gasoline Direct Injection Engines

Volume 2: Emissions Control Systems; Instrumentation, Controls, and Hybrids; Numerical Simulation; Engine Design and Mechanical Development ◽

10.1115/icef2017-3623 ◽

2017 ◽

Cited By ~ 1

Author(s):

Doohyun Kim ◽

Angela Violi ◽

André Boehman

Keyword(s):

Combustion Chamber ◽

Direct Injection ◽

Gasoline Direct Injection ◽

Injection Timing ◽

Charge Composition ◽

Gaseous Species ◽

Fuel Mass ◽

Soot Precursors ◽

Gdi Engine ◽

Fuel Mixing

Increased Particulate Matter (PM) emissions from Gasoline Direct Injection (GDI) engines compared to conventional Port Fuel Injection (PFI) engines have been raising concerns because of the PM’s detrimental health effects and the stringent emissions regulations. One of the widely accepted hypotheses is that local rich pockets inside the combustion chamber are the primary reason for the increased PM emissions. In this paper, we investigate the effects of injection strategies on the charge composition and local thermodynamic conditions of a light duty GDI engine, and determine their impact on PM emissions. The operation of a 1.6L GDI engine is simulated using a 3-D Computational Fluid Dynamics (CFD) code. Combustion characteristics of a 3-component gasoline surrogate (n-heptane/iso-octane/toluene) are analyzed and the effects of injection timing (300° vs 240° vs 180° BTDC) and injected fuel mass (globally stoichiometric vs fuel rich) are explored at 2000 rpm, 9.5 bar BMEP condition, focusing on the homogeneity of the charge and the formation of the gaseous species that are soot precursors. The results indicate that when the physical time for air/fuel mixing is not long enough, fuel-rich pockets are present until combustion occurs, where high concentrations of soot precursors are found, such as acetylene and pyrene. In addition, simulation results indicate that the location of wetted surface as well as the in-cylinder flow structure induced by the fuel jet hitting the piston bowl is significantly influenced by varying the injection timing, which affects subsequent air/fuel mixing. When the injected fuel mass is increased, the equivalence ratio distribution inside the combustion chamber shifts toward fuel-rich side, generating more mixtures with Φ > 1.5, where formation of acetylene and pyrene are favored.

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Analysis of the GDI Spray Dynamics Through Multidimensional Modeling and Flow Visualization in an Optically Accessible SI Engine

Volume 1: Applied Mechanics; Automotive Systems; Biomedical Biotechnology Engineering; Computational Mechanics; Design; Digital Manufacturing; Education; Marine and Aerospace Applications ◽

10.1115/esda2014-20477 ◽

2014 ◽

Author(s):

Michela Costa ◽

Ugo Sorge ◽

Paolo Sementa ◽

Alessandro Montanaro

Keyword(s):

Direct Injection ◽

Gasoline Direct Injection ◽

Si Engine ◽

Engine Model ◽

Working Cycle ◽

3D Engine ◽

Experimental Side ◽

The Difference ◽

Wall Interaction ◽

Injection Strategies

Present work is aimed at studying into detail mixture formation and combustion in a gasoline direct injection (GDI) engine working under stoichiometric mixture conditions. The study is performed both numerically and experimentally. From the experimental side, the engine, optically accessible, is characterized by collecting, for various injection strategies, in-cylinder pressure cycles and digital images. From the numerical side, a 3D engine model is developed, that includes proper sub-models for the spray dynamics and the spray-wall interaction. This last phenomenon is studied into detail by resorting to a preliminary 3D simulation of the spray impingement realized in a proper experiment, where the engine injector is mounted at a certain distance from a cold or hot wall. An interesting comparison between numerical and experimental images of the in-cylinder spray dynamics is presented, that also allows individuating the difference in the wallfilm deposition under various injection strategies. This opens the way to understand the difference in the combustion development arising as injection is anticipated or retarded in the engine working cycle.

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Simulation Study of Injection Strategy and Tumble Effect on the Mixture Formation and Spray Impingement in a Gasoline Direct Injection Engine

10.4271/2014-01-1129 ◽

2014 ◽

Cited By ~ 3

Author(s):

Song Han ◽

Jing Qin ◽

Manqun Lin ◽

Yanrong Li ◽

Yidan Zhang

Keyword(s):

Simulation Study ◽

Direct Injection ◽

Gasoline Direct Injection ◽

Mixture Formation ◽

Injection Strategy ◽

Direct Injection Engine ◽

Gasoline Direct Injection Engine ◽

Spray Impingement

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Analysis of cycle-by-cycle variation in a direct injection gasoline engine using a laser-induced fluorescence technique

International Journal of Engine Research ◽

10.1243/146808703321533286 ◽

2003 ◽

Vol 4 (2) ◽

pp. 143-153 ◽

Cited By ~ 15

Author(s):

T Fujikawa ◽

Y Nomura ◽

Y Hattori ◽

T Kobayashi ◽

M Kanda

Keyword(s):

Gasoline Engine ◽

Direct Injection ◽

Mixture Distribution ◽

Fuel Mixture ◽

Laser Induced Fluorescence ◽

Injection Timing ◽

Indicated Mean Effective Pressure ◽

Cycle Variation ◽

Spark Timing ◽

Direct Injection Gasoline Engine

To analyse the cycle-by-cycle variation of combustion in a direct injection gasoline engine equipped with a fan-shape spray nozzle and operated with exhaust gas recirculation (EGR), the fuel mixture distribution was measured at a time of spark and during the combustion period by the laser-induced fluorescence (LIF) technique. It was found that in the case of advanced or retarded injection timing, the initial combustion period tends to extend and the indicated mean effective pressure (i.m.e.p.) becomes low when lean mixtures appear at the spark position and at the spark timing. This suggests that the cycle-by-cycle variation of combustion under these conditions is dominated by the fuel concentration at the spark position and spark timing. In contrast to this, for the best injection timing, which allows the lowest cycle-by-cycle variation, the i.m.e.p. fluctuation is affected not by the initial combustion period but by the main combustion period. The observation of LIF images revealed that the i.m.e.p. fluctuation at this condition is strongly correlated to the unburned mixture quantity at the side area of the piston cavity during the latter half of the combustion period. It was shown by a computational fluid dynamics (CFD) calculation that the combination of a uniform spray pattern and a compact cavity shape is effective to reduce the over-lean mixture region in the edge of the piston cavity, which is responsible for the cycle-by-cycle variation of combustion at the condition of best-tuned injection timing.

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Particulate Emission Reduction by Fuel Injection Timing Optimization in a Gasoline Direct Injection Engine

Journal of Energy Resources Technology ◽

10.1115/1.4051380 ◽

2021 ◽

pp. 1-19

Author(s):

Nikhil Sharma ◽

Avinash Kumar Agarwal

Keyword(s):

Fuel Injection ◽

Direct Injection ◽

Gasoline Direct Injection ◽

Superior Performance ◽

Transport Sector ◽

Injection Timing ◽

Particulate Emissions ◽

Particulate Emission ◽

Fuel Injection Timing ◽

Gdi Engine

Abstract Optimized fuel injection timings in internal combustion (IC) engines exhibit superior performance, combustion characteristics, and lower emissions. Particularly, particulate emissions from a gasoline direct injection (GDI) engine are highly dependent on fuel injection timings. GDI engines have emerged as a popular choice of powerplants for automobiles among customers. They are preferred over multiple-port fuel injection (MPFI) engines in the transport sector because of their superior fuel economy and performance characteristics. The main objective of this study was to optimize a GDI engine for the lowest particulate emission at different fuel injection timings. GDI engine was investigated for particulate matter (PM) mass/ particulate number (PN) emissions at five fuel injection timings (230, 250, 270, 290, 310 °btdc), which covered the entire envelope. Once the optimum fuel injection timing was determined, an engine exhaust particle sizer was used to measure the particle size-number distribution. Particulate samples from the engine were also collected on the filter paper for morphological investigations of particulates collected under optimized fuel injection timings. These experiments confirmed the importance and need to optimize the fuel injection timings at every engine operating point to reduce the PM/PN emissions from a GDI engine, which remains one of the biggest challenges to this technology.

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Effect of piston shape design on the scavenging performance and mixture preparation in a two-stroke boosted uniflow scavenged direct injection gasoline engine

International Journal of Engine Research ◽

10.1177/1468087419900072 ◽

2020 ◽

pp. 146808741990007 ◽

Cited By ~ 2

Author(s):

Xinyan Wang ◽

Hua Zhao

Keyword(s):

Gasoline Engine ◽

Direct Injection ◽

Shape Design ◽

Injection Timing ◽

Stoichiometric Mixture ◽

Split Injection ◽

Spark Plug ◽

Direct Injection Gasoline Engine ◽

Stroke Engine ◽

Injection Strategies

Compared to a four-stroke engine, the two-stroke engine doubles firing frequency and has favourable power-to-weight or power-to-volume ratio as well as engine downsizing to improve the overall powertrain fuel economy. In order to overcome the shortcomings of the conventional cross-flow or loop scavenged two-stroke engines, a two-stroke boosted uniflow scavenged direct injection gasoline engine was designed and its performance was analysed. In this study, three-dimensional computational fluid dynamics simulations were performed to understand the impact of the piston shape design on the scavenging process, in-cylinder flow formation, turbulence level and subsequent fuel/air mixing process in the boosted uniflow scavenged direct injection gasoline engine. Both single injection and split injection strategies were investigated to study the interactions between piston designs and fuel injection strategies to achieve stoichiometric mixture around the spark plug. The results show that the optimised piston with the same opening timing for all scavenge ports could achieve much better scavenging performance than the baseline piston design. In particular, the shallow pistons, that is, Piston #1 and Piston #4, could produce stoichiometric mixture around the spark plug with relatively lower inhomogeneity and higher turbulence kinetic energy around top dead centre when implementing the split injection strategy with start of injection timing at 250/310 °CA.

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Effect of Retarded Injection Timing on Knock Resistance and Cycle to Cycle Variation in Gasoline Direct Injection Engine

Journal of Energy Resources Technology ◽

10.1115/1.4039322 ◽

2018 ◽

Vol 140 (7) ◽

Cited By ~ 5

Author(s):

Lei Zhou ◽

Aifang Shao ◽

Jianxiong Hua ◽

Haiqiao Wei ◽

Dengquan Feng

Keyword(s):

Gasoline Engine ◽

Direct Injection ◽

High Energy ◽

Gasoline Direct Injection ◽

Injection Timing ◽

Spark Ignition Engines ◽

Compression Stroke ◽

Gasoline Direct Injection Engine ◽

Cycle Variation ◽

Electrically Actuated

In spark ignition engines, gasoline direct injection (GDI) is surely the most attractive technology to achieve the demand of high energy efficiency by directly injecting fuel into combustion chamber. This work, as a preliminary study, investigates the effect of retarded injection timing on knock resistance and cycle-to-cycle variation in gasoline engine by experimental method. The retarded injection timing during compression stroke coupled with increased intake air temperature was employed to concentrate on suppressing knock occurrence with stable combustion. Based on the great advantage of injection timing retard on knock suppression, intake temperature was used in this work to reduce cycle-to-cycle variation. In addition, piezo-electrically actuated injector was employed. The results show that injection timing retard during compression stroke can significantly suppress the knock tendency, but combustion becomes unstable and cycle-to-cycle variation is larger than 10%. Thus, increasing intake temperature decreased the cycle-to-cycle variation but increased significantly the knock tendency, as expect. Meanwhile, rich fuel–air mixture in this work also had the same effect as intake temperature did. It can be concluded that retarded injection timing is of significant potential to suppress the knock in GDI engine, although the high intake temperature causes high probability of large knock occurrence. The percentages of knock at the spark timings of 24 °CA before top dead center (BTDC) and 26 °CA BTDC were significantly reduced from approximately 40% to 7% and from approximately 60% to 10%, respectively. Furthermore, the retarded injection timing not only reduced the probability of knock occurrence, but also decreased the knock intensity obviously.

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Spray propagation and mixture formation in an air guided direct injection gasoline engine

International Journal of Engine Research ◽

10.1243/1468087001545119 ◽

2000 ◽

Vol 1 (2) ◽

pp. 163-170 ◽

Cited By ~ 4

Author(s):

P Adomeit ◽

O Lang ◽

S Pischinger

Keyword(s):

Gasoline Engine ◽

Cfd Simulation ◽

Direct Injection ◽

Operation Mode ◽

Cone Angle ◽

Injection Pressure ◽

Gasoline Direct Injection ◽

Orifice Diameter ◽

Charge Motion ◽

Mixture Formation

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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