A Quasi-dimensional Model of the Ignition Delay for Combustion Modeling in Spark-Ignition Engines

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Sebastian Grasreiner ◽  
Jens Neumann ◽  
Michael Wensing ◽  
Christian Hasse
Keyword(s):  
Ignition Delay ◽  
Direct Injection ◽  
Control Unit ◽  
Spark Ignition ◽  
Spark Ignition Engines ◽  
Combustion Modeling ◽  
Crank Angle ◽  
Si Engines ◽  
Engine Map ◽  
Start Of Combustion

Quasi-dimensional (QD) modeling of combustion in spark-ignition (SI) engines allows to describe the most relevant processes of heat release. Here, a submodel for the ignition delay is introduced and applied. The start of combustion is considered from ignition to the crank angle of 5% burned gas fraction. The introduced physical approach identifies the turbulent propagation velocity of the initiated kernel by taking into account early flame expansion and geometric restrictions of the flame propagation. The model is applied to stationary operation within an entire engine map of a turbocharged direct injection SI engine with fully variable valvetrain. Based on provided cycle-averaged input data, the model delivers good results within the margins of measured cycle-to-cycle fluctuations. Thus, it contributes to the assessment of the interplay between engine, engine control unit, drivetrain, and vehicle dynamics, hence making a step toward optimization and virtual engine calibration.

A phenomenological mixture homogenization model for spark-ignition direct-injection engines

2017 ◽  
Vol 19 (2) ◽  
pp. 168-178 ◽  
Author(s):  
Stefan Frommater ◽  
Jens Neumann ◽  
Christian Hasse
Keyword(s):  
Equivalence Ratio ◽  
Direct Injection ◽  
Three Dimensional ◽  
Control Unit ◽  
Spark Ignition ◽  
Engine Control Unit ◽  
Operating Conditions ◽  
Spark Ignition Engines ◽  
Ratio Distribution ◽  
Direct Injection Spark Ignition

In modern turbocharged direct-injection, spark-ignition engines, proper calibration of the engine control unit is essential to handle the increasing variability of actuators. The physically based simulation of engine processes such as mixture homogenization enables a model-based calibration of the engine control unit to identify an ideal set of actuator settings, for example, for efficient combustion with reduced exhaust emissions. In this work, a zero-dimensional phenomenological model for direct-injection, spark-ignition engines is presented that allows the equivalence ratio distribution function in the combustion chamber to be calculated and its development is tracked over time. The model considers the engine geometry, mixing time, charge motion and spray–charge interaction. Accompanying three-dimensional computational fluid dynamics, simulations are performed to obtain information on homogeneity at different operating conditions and to calibrate the model. The calibrated model matches the three-dimensional computational fluid dynamics reference both for the temporal homogeneity development and for the equivalence ratio distribution at the ignition time, respectively. When the model is validated outside the calibrated operating conditions, this shows satisfying results in terms of mixture homogeneity at the time of ignition. Additionally, only a slight modification of the calibration is shown to be required when transferring the model to a comparable engine. While the model is primarily aimed at target applications such as a direct-injection, spark-ignition soot emission model, its application to other issues, such as gaseous exhaust emissions, engine knock or cyclic fluctuations, is conceivable due to its general structure. The fast calculation enables mixture inhomogeneities to be estimated during driving cycle simulations.

Data Driven Feedforward Transient Fueling Controller Identification for Spark Ignition Engines

2005 ◽  
Author(s):  
Matthew A. Franchek ◽  
Jackie Mohrfeld ◽  
Andy Osburn
Keyword(s):  
Steady State ◽  
Nonlinear Behavior ◽  
Spark Ignition ◽  
Spark Ignition Engines ◽  
Transient Phenomena ◽  
Crank Angle ◽  
Si Engines ◽  
Separate System ◽  
Feedforward Controller ◽  
Fueling Control

Presented in this paper is a feedforward fueling controller identification methodology for the transient fueling control of spark ignition (SI) engines. The proposed transient feedforward controller is identified and executed in the crank angle domain, and operates in tandem with a steady state fueling controller. The hypothesis is that the feedforward fueling control of SI engines can be separated into steady state and transient phenomena, and that the majority of the nonlinear behavior associated with engine fueling can be captured with nonlinear steady state compensation. The proposed transient controller identification process is built from standard nonparametric identification techniques using spectral density functions where crank angle serves as the independent variable. Two separate system identification problems are solved to identify the air path dynamics and the fuel path dynamics. The transient feedforward controller is then calculated as the ratio of the air path-over-the fuel path dynamics so that the fuel path dynamics match the air path dynamics. Consequently fueling is coordinated with the fresh air charge during transient conditions. It will be shown that a linear transient feedforward-fueling controller operating in tandem with a nonlinear steady state fueling controller can achieve air-fuel ratio (AFR) regulation comparable to a production controller without the extensive controller calibration process. The engine used in this investigation is a 1999 Ford 4.6L V-8 fuel injected engine.

A New Approach for Ignition Timing Correction in Spark Ignition Engines Based on Cylinder Tendency to Surface Ignition

2016 ◽  
Vol 819 ◽  
pp. 272-276 ◽  
Author(s):  
Ali Ghanaati ◽  
Mohd Farid Muhamad Said ◽  
Intan Zaurah Mat Darus ◽  
Amin Mahmoudzadeh Andwari
Keyword(s):  
Spark Ignition ◽  
Combustion Stability ◽  
Spark Ignition Engines ◽  
Gas Temperature ◽  
New Approach ◽  
Surface Ignition ◽  
Spark Plug ◽  
Engine Combustion ◽  
Si Engines ◽  
Exhaust Gas Temperature

The performance of Spark Ignition (SI) engines in terms of thermal efficiency can be restricted by knock. Although it is common for all SI engines to exhibit knock from compressed end-gas, knocks from surface ignition remains a more serious problem due to its effect on combustion stability and its obscurity to detect. This paper focuses on predicting the occurrence of knocks from surface ignition by monitoring exhaust gas temperature (EGT). EGT measured during an engine cycle without the spark plug firing. Therefore, EGT rises illustrated any combustion made by surface ignition. Modelling and simulation of a one-dimensional engine combustion done by using GT-Power. The new approach reduces the complexity as EGT monitoring does not require high computational demands, and the EGT signals are robust to noise. The method is validated against a variety of fuel properties and across engine conditions. A new approach is proposed as a measure to predict and detect the knock events.

scholarly journals Phenomenological model for determining velocity field of LPG jet in combustion chamber of direct injection S.I. engine

2004 ◽  
Vol 26 (2) ◽  
pp. 83-92
Author(s):  
Bui Van Ga ◽  
Phung Xuan Tho ◽  
Nhan Hong Quang ◽  
Nguyen Huu Huong
Keyword(s):  
Combustion Chamber ◽  
Phenomenological Model ◽  
Direct Injection ◽  
Spark Ignition ◽  
Velocity Profiles ◽  
Gas Jet ◽  
Liquefied Petroleum Gas ◽  
Si Engine ◽  
Si Engines ◽  
Stratified Combustion

A phenomenological model has been established to predict the velocity distribution of LPG (Liquefied Petroleum Gas) jet in combustion chamber of spark ignition (SI) engine. A shaped coefficient \(\beta\) governing the similarity of velocity profiles of LPG jets has been defined based on the theoretical and experimental analyses of turbulent diffusion jets. The results show that \(\beta\) is constant for steady jet but it is not the case for unsteady one. The model will enable us to calculate the velocity profiles of LPG jet after ending injection. This is necessary for research of stratified combustion in direct injection LPG SI engines.

scholarly journals LES study on mixing and combustion in a Direct Injection Spark Ignition engine

2018 ◽  
Vol 73 ◽  
pp. 32
Author(s):  
Nicolas Iafrate ◽  
Anthony Robert ◽  
Jean-Baptiste Michel ◽  
Olivier Colin ◽  
Benedicte Cuenot ◽  
...  
Keyword(s):  
Ignition Time ◽  
Direct Injection ◽  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Pollutant Emissions ◽  
Spark Ignition Engines ◽  
Eddy Simulation ◽  
Mixture Preparation ◽  
The Impact

Downsized spark ignition engines coupled with a direct injection strategy are more and more attractive for car manufacturers in order to reduce pollutant emissions and increase efficiency. However, the combustion process may be affected by local heterogeneities caused by the interaction between the spray and turbulence. The aim for car manufacturers of such engine strategy is to create, for mid-to-high speeds and mid-up-high loads, a mixture which is as homogeneous as possible. However, although injection occurs during the intake phase, which favors homogeneous mixing, local heterogeneities of the equivalence ratio are still observed at the ignition time. The analysis of the mixture preparation is difficult to perform experimentally because of limited optical accesses. In this context, numerical simulation, and in particular Large Eddy Simulation (LES) are complementary tools for the understanding and analysis of unsteady phenomena. The paper presents the LES study of the impact of direct injection on the mixture preparation and combustion in a spark ignition engine. Numerical simulations are validated by comparing LES results with experimental data previously obtained at IFPEN. Two main analyses are performed. The first one focuses on the fuel mixing and the second one concerns the effect of the liquid phase on the combustion process. To highlight these phenomena, simulations with and without liquid injection are performed and compared.

scholarly journals Study on the Effect of Second Injection Timing on the Engine Performances of a Gasoline/Hydrogen SI Engine with Split Hydrogen Direct Injecting

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5223
Author(s):  
Guanting Li ◽  
Xiumin Yu ◽  
Ping Sun ◽  
Decheng Li
Keyword(s):  
Numerical Study ◽  
Direct Injection ◽  
Mixture Distribution ◽  
Spark Ignition ◽  
Injection Timing ◽  
Si Engine ◽  
Excess Air ◽  
Crank Angle ◽  
Hc Emissions ◽  
Main Factor

Split hydrogen direct injection (SHDI) has been proved capable of better efficiency and fewer emissions. Therefore, to investigate SHDI deeply, a numerical study on the effect of second injection timing was presented at a gasoline/hydrogen spark ignition (SI) engine with SHDI. With an excess air ratio of 1.5, five different second injection timings achieved five kinds of hydrogen mixture distribution (HMD), which was the main factor affecting the engine performances. With SHDI, since the HMD is manageable, the engine can achieve better efficiency and fewer emissions. When the second injection timing was 105° crank angle (CA) before top dead center (BTDC), the Pmax was the highest and the position of the Pmax was the earliest. Compared with the single hydrogen direct injection (HDI), the NOX, CO and HC emissions with SHDI were reduced by 20%, 40% and 72% respectively.

scholarly journals Numerical investigations on hydrogen-enhanced combustion in ultra-lean gasoline spark-ignition engines

2019 ◽  
pp. 146808741987068 ◽  
Author(s):  
Nicolas Iafrate ◽  
Mickael Matrat ◽  
Jean-Marc Zaccardi
Keyword(s):  
Ignition Delay ◽  
Combustion Process ◽  
Spark Ignition ◽  
Combustion Stability ◽  
Spark Ignition Engines ◽  
Numerical Investigations ◽  
Ignition Delay Times ◽  
Auto Ignition ◽  
Delay Times ◽  
Combustion Speed

Performance of lean-burn gasoline spark-ignition engines can be enhanced through hydrogen supplementation. Thanks to its physicochemical properties, hydrogen supports the flame propagation and extends the dilution limits with improved combustion stability. These interesting features usually result in decreased emissions and improved efficiencies. This article aims at demonstrating how hydrogen can support the combustion process with a modern combustion system optimized for high dilution resistance and efficiency. To achieve this, chemical kinetics calculations are first performed in order to quantify the impacts of hydrogen addition on the laminar flame speed and on the auto-ignition delay times of air/gasoline mixtures. These data are then implemented in the extended coherent flame model and tabulated kinetics of ignition combustion models in a specifically updated version of the CONVERGE code. Three-dimensional computational fluid dynamics engine calculations are performed at λ = 2 with 3% v/v of hydrogen for two operating points. At low load, numerical investigations show that hydrogen enhances the maximal combustion speed and the flame growth just after the spark which is a critical aspect of combustion with diluted mixtures. The flame front propagation is also more isotropic when supported with hydrogen. At mid load, hydrogen improves the combustion speed and also extends the auto-ignition delay times resulting in a better knocking resistance. A maximal indicated efficiency of 48.5% can thus be reached at λ = 2 thanks to an optimal combustion timing.

scholarly journals A Fast CFD-Based Methodology for Determining the Cyclic Variability and Its Effects on Performance and Emissions of Spark-Ignition Engines

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4131
Author(s):  
George M. Kosmadakis ◽  
Constantine D. Rakopoulos
Keyword(s):  
Spark Ignition ◽  
Pollutant Emissions ◽  
Computational Time ◽  
Spark Ignition Engines ◽  
Cyclic Variability ◽  
Indicated Mean Effective Pressure ◽  
Spark Plug ◽  
Performance And Emissions ◽  
Si Engines ◽  
Cyclic Variations

A methodology for determining the cyclic variability in spark-ignition (SI) engines has been developed recently, with the use of an in-house computational fluid dynamics (CFD) code. The simulation of a large number of engine cycles is required for the coefficient of variation (COV) of the indicated mean effective pressure (IMEP) to converge, usually more than 50 cycles. This is valid for any CFD methodology applied for this kind of simulation activity. In order to reduce the total computational time, but without reducing the accuracy of the calculations, the methodology is expanded here by simulating just five representative cycles and calculating their main parameters of concern, such as the IMEP, peak pressure, and NO and CO emissions. A regression analysis then follows for producing fitted correlations for each parameter as a function of the key variable that affects cyclic variability as has been identified by the authors so far, namely, the relative location of the local turbulent eddy with the spark plug. The application of these fitted correlations for a large number of engine cycles then leads to a fast estimation of the key parameters. This methodology is applied here for a methane-fueled SI engine, while future activities will examine cyclic variations in SI engines when fueled with different fuels and their mixtures, such as methane/hydrogen blends, and their associated pollutant emissions.

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