scholarly journals Optical Investigation of a Partial Fuel Stratification Strategy to Stabilize Overall Lean Operation of a DISI Engine Fueled with Gasoline and E30

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 396
Author(s):  
Cinzia Tornatore ◽  
Magnus Sjöberg
Keyword(s):  
Volume Fraction ◽  
Direct Injection ◽  
Combustion Process ◽  
Pilot Injection ◽  
Optical Investigation ◽  
Flame Kernel ◽  
Lean Combustion ◽  
Fuel Stratification ◽  
Spark Plug ◽  
Initial Flame

This paper offers new insights into a partial fuel stratification (PFS) combustion strategy that has proven to be effective at stabilizing overall lean combustion in direct injection spark ignition engines. To this aim, high spatial and temporal resolution optical diagnostics were applied in an optically accessible engine working in PFS mode for two fuels and two different durations of pilot injection at the time of spark: 210 µs and 330 µs for E30 (gasoline blended with ethanol by 30% volume fraction) and gasoline, respectively. In both conditions, early injections during the intake stroke were used to generate a well-mixed lean background. The results were compared to rich, stoichiometric and lean well-mixed combustion with different spark timings. In the PFS combustion process, it was possible to detect a non-spherical and highly wrinkled blue flame, coupled with yellow diffusive flames due to the combustion of rich zones near the spark plug. The initial flame spread for both PFS cases was faster compared to any of the well-mixed cases (lean, stoichiometric and rich), suggesting that the flame propagation for PFS is enhanced by both enrichment and enhanced local turbulence caused by the pilot injection. Different spray evolutions for the two pilot injection durations were found to strongly influence the flame kernel inception and propagation. PFS with pilot durations of 210 µs and 330 µs showed some differences in terms of shapes of the flame front and in terms of extension of diffusive flames. Yet, both cases were highly repeatable.

Engine performance monitoring using spark plug voltage analysis

1997 ◽  
Vol 211 (6) ◽  
pp. 499-509 ◽  
Author(s):  
H Zhao ◽  
N Ladommatos
Keyword(s):  
Decay Time ◽  
Performance Monitoring ◽  
Effective Means ◽  
Combustion Process ◽  
Engine Performance ◽  
Easy Access ◽  
Flame Kernel ◽  
Voltage Decay ◽  
Spark Plug ◽  
Initial Flame

Spark plug based engine combustion diagnostics have the advantage of simplicity and easy access. Over the years there has been considerable interest in developing and applying spark plug ionization probes to monitor the in-cylinder combustion process. In this paper, alternative approaches are presented using the spark plug as the primary sensor. These methods are based on the analysis of the spark voltage and a secondary high-voltage discharge. A series of experiments have been conducted to evaluate their potential in the measurement of combustion quality and the detection of misfire. It is found that the spark voltage decay time is related to the initial flame kernel development and may be used to detect misfire and deteriorating combustion quality in the initial flame development. The results also show that the analysis of secondary voltage decay time could be an effective means of monitoring the combustion quality and detecting misfire during the main combustion period.

scholarly journals Experimental study of multiple pilot injection strategy in an automotive direct injection diesel engine

2018 ◽  
Vol 234 ◽  
pp. 03007
Author(s):  
Plamen Punov ◽  
Tsvetomir Gechev ◽  
Svetoslav Mihalkov ◽  
Pierre Podevin ◽  
Dalibor Barta
Keyword(s):  
Experimental Study ◽  
Diesel Engine ◽  
Diesel Engines ◽  
Direct Injection ◽  
Combustion Process ◽  
Injection Timing ◽  
Pilot Injection ◽  
Injection Strategy ◽  
Direct Injection Diesel Engine ◽  
Rate Of Heat Release

The pilot injection strategy is a widely used approach for reducing the noise of the combustion process in direct injection diesel engines. In the last generation of automotive diesel engines up to several pilot injections could occur to better control the rate of heat release (ROHR) in the cylinder as well as the pollutant formation. However, determination of the timing and duration for each pilot injection needs to be precisely optimised. In this paper an experimental study of the pilot injection strategy was conducted on a direct injection diesel engine. Single and double pilot injection strategy was studied. The engine rated power is 100 kW at 4000 rpm while the rated torque is 320 Nm at 2000 rpm. An engine operating point determined by the rotation speed of 1400 rpm and torque of 100 Nm was chosen. The pilot and pre-injection timing was widely varied in order to study the influence on the combustion process as well as on the fuel consumption.

Simulation Study about Dual Spark Plug Position for the CNG Engine Combustion Process

2013 ◽  
Vol 712-715 ◽  
pp. 1197-1200 ◽  
Author(s):  
Chang Qing Song ◽  
Jun Li ◽  
Da Wei Qu ◽  
Kai Yu
Keyword(s):  
Flame Propagation ◽  
Combustion Process ◽  
Three Dimensional ◽  
Propagation Distance ◽  
Simulation Software ◽  
Flame Surface ◽  
Flame Kernel ◽  
Spark Plug ◽  
Cng Engine ◽  
Combustion Speed

The paper has modeled and simulated the combustion process of big bore CNG engine by three-dimensional simulation software AVL FRIE. Based on test validation in the model, the effect on position of the dual spark plug for cylinder initial flame kernel development and flame propagation process was researched. The results showed that: When A=0.5, the flame propagation distance shortened by half, a certain intensity of turbulence formed when the compression stroke ended, the combustion speed was the fastest, the combustion duration was the shortest. If dual spark plug spacing is too small, the two flames meet prematurely will cause interfere with each other, and reduce the combustion speed of the overlapping region of the flame surface, increase the heat losses. Otherwise,if the distance is too large , close to the combustion chamber wall, the combustion space is narrow, the flame propagation space is restricted, then flame development is slow.

Effect of Discharge Energy Distribution on Flame Kernel Development

2020 ◽  
Author(s):  
Hua Zhu ◽  
Xiao Yu ◽  
Linyan Wang ◽  
Ming Zheng ◽  
Liguang Li ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Combustion Process ◽  
Operating Conditions ◽  
Discharge Energy ◽  
Energy Strategy ◽  
Ignition Energy ◽  
Lean Burn ◽  
Flame Kernel ◽  
Constant Volume Combustion Chamber ◽  
Initial Flame

Abstract The early flame kernel initiation and development are essential to a successful combustion process, especially under lean burn/EGR diluted conditions. Multiple ignition sites strategy has shown promise to secure the flame kernel initiation under extreme engine operating conditions. Two factors are considered to contribute to the enhanced ignition capability, i.e. the higher ignition energy and the multiple initial flame kernels. However, the mechanism why the multiple ignition sites help combustion is less understood. In this work, the impacts of the ignition energy distribution strategy on the flame inception process are investigated in a constant volume combustion chamber. A multi-coil ignition system, along with a sparkplug with three high-voltage electrodes, is used to adjust the discharge energy from 10 mJ to 240 mJ, as well as the energy deposition strategies. Experimental results have shown that the distributed energy strategy with sufficient discharge energy can establish a bigger initial flame kernel, leading to faster flame growth rates, as compared to the concentrated energy strategy.

scholarly journals Analysis of mixture formation process in a two-stroke boosted uniflow scavenged direct injection gasoline engine

2017 ◽  
Vol 19 (9) ◽  
pp. 927-940 ◽  
Author(s):  
Xinyan Wang ◽  
Jun Ma ◽  
Hua Zhao
Keyword(s):  
Gasoline Engine ◽  
Single Injection ◽  
Direct Injection ◽  
Fuel Stratification ◽  
Mixture Preparation ◽  
Spark Plug ◽  
Start Of Injection ◽  
Flow Motion ◽  
Direct Injection Gasoline Engine ◽  
Cylinder Flow

The two-stroke engine has the great potential for aggressive engine downsizing and downspeeding because of its double firing frequency. For a given torque, it is characterized with a lower mean effective pressure and lower peak in-cylinder pressure than a four-stroke counterpart. In order to explore the potential of two-stroke cycle while avoiding the drawbacks of conventional ported two-stroke engines, a novel two-stroke boosted uniflow scavenged direct injection gasoline engine was proposed and designed. In order to achieve the stable lean-burn combustion in the boosted uniflow scavenged direct injection gasoline engine, the mixture preparation, especially the fuel stratification around the spark plug, should be accurately controlled. As the angled intake scavenge ports produce strong swirl flow motion and complex transfer between the swirl and tumble flows in the two-stroke boosted uniflow scavenged direct injection gasoline engine, the interaction between the in-cylinder flow motions and the direct injection and its impact on the charge preparation in the boosted uniflow scavenged direct injection gasoline engine are investigated in this study by three-dimensional computational fluid dynamics simulations. Both the single injection and split injections are applied and their impact on the mixture formation process is investigated. The start of injection timing and split injection ratio are adjusted accordingly to optimize the charge preparation for each injection strategy. The results show that the strong interaction between the fuel injection and in-cylinder flow motions dominates the mixture preparation in the boosted uniflow scavenged direct injection gasoline engine. Compared to the single injection, the split injection shows less impact on the large-scale flow motions. Good fuel stratification around the spark plug was obtained by the late start of injection timings at 300 °CA/320 °CA with an equal amount in each injection. However, when a higher tumble flow motion is produced by the eight scavenge ports’ design, a better fuel charge stratification can be achieved with the later single injection at start of injection of 320 °CA.

Validation of a Lagrangian Ignition Model in SI Engine Simulations

2010 ◽  
Author(s):  
Claudio Forte ◽  
Gian Marco Bianchi ◽  
Enrico Corti
Keyword(s):  
Gas Flow ◽  
Fuel Mixture ◽  
Electrical Circuit ◽  
Expansion Velocity ◽  
Ignition Process ◽  
Time Step ◽  
Flame Kernel ◽  
Spark Plug ◽  
Turbulence Effects ◽  
Initial Flame

Ignition process plays a key role in flame kernel formation and heavily affects further combustion development. The paper aim is to present a 1D lagrangian ignition model and to validate it against real engine configurations. A lump model for the electrical circuit of the spark plug is used to compute breakdown and glow energy. At the end of shock wave and very first plasma expansion, a spherical kernel is deposited inside the gas flow at spark plug location. A simple model allows computing initial flame kernel radius and temperature based on physical mixture properties and spark plug characteristics. The sphere surface of the kernel is discretized by triangular elements which move radially according to a lagrangian approach. Expansion velocity is computed accounting for both heat conduction effect at the highest temperatures and thermodynamic energy balance at relatively lower temperatures. Turbulence effects and thermodynamic properties of the air-fuel mixture are accounted for. Restrikes are possible depending on gas flow velocity and mixture quality at spark location. CFD solver and 1D/lagrangian ignition model are closely coupled at each time step. The model proves to strongly reduce the grid sensitivity. The CFD model validation phase is crucial for a correct representation of both kernel formation and combustion development: the operation has been carried out by means of an accurate statistical analysis of experimental in-cylinder pressure data in real engine configurations.

A Study on the Spray Characteristics of SIDI CNG Engine Based on a Visualization System

2013 ◽  
Vol 860-863 ◽  
pp. 1060-1064 ◽  
Author(s):  
Yu Liu ◽  
Guo Chang Zhao ◽  
Zhi Hai Kou ◽  
S. S. Chung
Keyword(s):  
Alternative Fuels ◽  
Direct Injection ◽  
Spray Characteristics ◽  
Promising Alternative ◽  
Visualization System ◽  
Lean Combustion ◽  
Injection Process ◽  
Spark Plug ◽  
Automobile Engines ◽  
Cng Engine

Compressed natural gas (CNG) is regarded as one of the most promising alternative fuels, is widely used for the automobile engines. In order to improve the thermal efficiency of CNG engine, the direct-injection (DI) technology has been adopted. The stratified CNG mixture can be ignited by the spark plug which is installed near the injector nozzle, so the lean combustion can be subsequently achieved. For the direct-injection spark-ignition (DISI) engine, the reliable ignition is a foundational problem for the reliable operation, so it is very important to study on the spray characteristics of DISI engine. In our study, a combustion chamber is designed and a visualization system is built. The DI CNG spray's injection process was digital recorded with the schlieren optical system under different experiment conditions. The spray characteristics of the DI CNG engine were analyzed with the experimental results.

The Effect of Intake Valve Deactivation on Lean Stratified Charge Combustion at an Idling Condition of a Spark Ignition Direct Injection Engine

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Ronald O. Grover ◽  
Junseok Chang ◽  
Edward R. Masters ◽  
Paul M. Najt ◽  
Aditya Singh
Keyword(s):  
Laminar Flame ◽  
Direct Injection ◽  
Combustion Process ◽  
Spark Ignition ◽  
Combustion Efficiency ◽  
Combustion Stability ◽  
Charge Motion ◽  
Piston Bowl ◽  
Light Load ◽  
Spark Plug

A combined experimental and analytical study was carried out to understand the improvement in combustion performance of a four-valve spark ignition direct injection (SIDI) wall-guided engine operating at lean, stratified idle with enhanced in-cylinder charge motion by deactivating one of the two intake valves. A fully warmed-up engine was operated at low speed, light load by injecting the fuel from a pressure-swirl injector during the compression stroke to produce a stratified fuel cloud surrounding the spark plug at the time of ignition. Steady state flow-bench measurements and computational fluid dynamics (CFD) calculations showed that valve deactivation primarily increased the in-cylinder swirl intensity as compared with opening both intake valves. Engine dynamometer measurements showed an increase in charge motion led to improved combustion stability, increased combustion efficiency, lower fuel consumption, and higher dilution tolerance. A CFD study was conducted using in-house models of spray and combustion to simulate the engine operating with and without valve deactivation. The computations demonstrated that the improved combustion was primarily driven by higher laminar flame speeds through enhanced mixing of internal residual gases, better containment of the fuel cloud within the piston bowl, and higher postflame diffusion burn rates during the initial, main, and late stages of the combustion process, respectively.

A Numerical Investigation of Combustion and Mixture Formation in a Compressed Natural Gas DISI Engine With Centrally Mounted Single-Hole Injector

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
B. Yadollahi ◽  
M. Boroomand
Keyword(s):  
Natural Gas ◽  
Internal Combustion Engines ◽  
Gasoline Engine ◽  
Direct Injection ◽  
Combustion Process ◽  
Spark Ignition ◽  
Computational Effort ◽  
Single Hole ◽  
Piston Head ◽  
Spark Plug

Direct injection of natural gas into the cylinder of spark ignition (SI) engines has shown a great potential to achieve the best fuel economy and reduced emission levels. Since the technology is rather new, in-cylinder flow phenomena have not been completely investigated. In this study, a numerical model has been developed in AVL FIRE software to perform an investigation of natural gas direct injection into the cylinder of spark ignition internal combustion engines. In this regard, two main parts have been taken into consideration aiming to convert a multipoint port fuel injection (MPFI) gasoline engine to a direct injection natural gas (NG) engine. In the first part of the study, multidimensional simulations of transient injection process, mixing, and flow field have been performed. Using the moving mesh capability, the validated model has been applied to methane injection into the cylinder of a direct injection engine. Five different piston head shapes have been taken into consideration in the investigations. An inwardly opening single-hole injector has been adapted to all cases. The injector location has been set to be centrally mounted. The effects of combustion chamber geometry have been studied on the mixing of air-fuel inside the cylinder via the quantitative and qualitative representation of results. In the second part, an investigation of the combustion process has been performed on the selected geometry. The spark plug location and ignition timing have been studied as two of the most important variables. Simulation of transient injection was found to be a challenging task because of required computational effort and numerical instabilities. Injection results showed that the narrow bowl piston head geometry is the most suited geometry for NG direct injection (DI) application. A near center position has been shown to be the best spark plug location based on the combustion studies. It has been shown that advanced ignitions timings of up to 50 degrees crank angle ( °CA) should be used in order to obtain better combustion performance.

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