High-Fidelity Energy Deposition Ignition Model Coupled With Flame Propagation Models at Engine-Like Flow Conditions

2021 ◽  
Author(s):  
Samuel J. Kazmouz ◽  
Riccardo Scarcelli ◽  
Joohan Kim ◽  
Zhen Cheng ◽  
Shuaishuai Liu ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Energy Deposition ◽  
Spark Ignition ◽  
Grid Size ◽  
High Fidelity ◽  
Ignition Process ◽  
Time Step ◽  
Engine Operation ◽  
Propagation Models ◽  
Spark Channel

Abstract With the heightened pressure on car manufacturers to increase the efficiency and reduce the carbon emissions of their fleets, more challenging engine operation has become a viable option. Highly dilute, boosted, and stratified charge, among others, promise engine efficiency gains and emissions reductions. At such demanding engine conditions, the spark-ignition process is a key factor for the flame initiation propagation and the combustion event. From a computational standpoint, there exists multiple spark-ignition models that perform well under conventional conditions but are not truly predictive under strenuous engine operation modes, where the underlying physics needs to be expanded. In this paper, a hybrid Lagrangian-Eulerian spark-ignition (LESI) model is coupled with different turbulence models, grid sizes, and combustion models. The ignition model, previously developed, relies on coupling Eulerian energy deposition with a Lagrangian particle evolution of the spark channel, at every time-step. The spark channel is attached to the electrodes and allowed to elongate at a speed derived from the flow velocity. The LESI model is used to simulate spark ignition in a non-quiescent crossflow environment at engine-like conditions, using CONVERGE commercial CFD solver. The results highlight the consistency, robustness, and versatility of the model in a range of engine-like setups, from typical with RANS and a larger grid size to high fidelity with LES and a finer grid size. The flame kernel growth is then evaluated against schlieren images from an optical constant volume ignition chamber with a focus on the performance of flame propagation models, such as G-equation and thickened flame model, versus the baseline well-stirred reactor model. Finally, future development details are discussed.

scholarly journals Development of a Hybrid Lagrangian–Eulerian Model to Describe Spark-Ignition Processes at Engine-Like Turbulent Flow Conditions

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Riccardo Scarcelli ◽  
Anqi Zhang ◽  
Thomas Wallner ◽  
Sibendu Som ◽  
Jing Huang ◽  
...  
Keyword(s):  
Energy Deposition ◽  
Combustion Process ◽  
Spark Ignition ◽  
Computational Time ◽  
Ignition Process ◽  
Time Step ◽  
Eulerian Model ◽  
Constant Volume Chamber ◽  
Spark Channel ◽  
Deposition Models

With the engine technology moving toward more challenging (highly dilute and boosted) operation, spark-ignition processes play a key role in determining flame propagation and completeness of the combustion process. On the computational side, there is plenty of spark-ignition models available in literature and validated under conventional, stoichiometric spark ignition (SI) operation. Nevertheless, these models need to be expanded and developed on more physical grounds since at challenging operation they are not truly predictive. This paper reports on the development of a dedicated model for the spark-ignition event at nonquiescent, engine-like conditions, performed in the commercial CFD code converge. The developed methodology leverages previous findings that have expanded the use and improved the accuracy of Eulerian-type energy deposition models. In this work, the Eulerian energy deposition is coupled at every computational time-step with a Lagrangian-type evolution of the spark channel. Typical features such as spark channel elongation, stretch, and attachment to the electrodes are properly described to deliver realistic energy deposition along the channel during the entire ignition process. The numerical results are validated against schlieren images from an optical constant volume chamber and show the improvement in the simulation of the spark channel during the entire ignition event, with respect to the most commonly used energy deposition approach. Further developmental pathways are discussed to provide more physics-based features from the developed ignition model in the future.

scholarly journals Development of a Hybrid Lagrangian-Eulerian Model to Describe Spark-Ignition Processes at Engine-Like Turbulent Flow Conditions

2018 ◽  
Author(s):  
Riccardo Scarcelli ◽  
Anqi Zhang ◽  
Thomas Wallner ◽  
Sibendu Som ◽  
Jing Huang ◽  
...  
Keyword(s):  
Energy Deposition ◽  
Combustion Process ◽  
Spark Ignition ◽  
Computational Time ◽  
Ignition Process ◽  
Time Step ◽  
Eulerian Model ◽  
Constant Volume Chamber ◽  
Spark Channel ◽  
Further Development

With the engine technology moving towards more challenging (highly dilute and boosted) operation, spark-ignition processes play a key role in determining flame propagation and completeness of the combustion process. On the computational side, there is plenty of spark-ignition models available in literature and validated under conventional, stoichiometric SI operation. Nevertheless, these models need to be expanded and developed on more physical grounds since at challenging operation they are not truly predictive. This paper reports on the development of a dedicated model for the spark-ignition event at non-quiescent, engine-like conditions, performed in the commercial CFD code CONVERGE. The developed methodology leverages previous findings that have expanded the use and improved the accuracy of Eulerian-type energy deposition models. In this work, the Eulerian energy deposition is coupled at every computational time-step with a Lagrangian-type evolution of the spark channel. Typical features such as spark channel elongation, stretch, attachment to the electrodes are properly described to deliver realistic energy deposition along the channel during the entire ignition process. The numerical results are validated against schlieren images from an optical constant volume chamber and show the improvement in the simulation of the spark channel during the entire ignition event, with respect to the most commonly used energy deposition approach. Further development pathways are discussed to provide more physics-based features from the developed ignition model in the future.

CFD Prediction for an Overpressure Buildup Phenomenon of SRI Hydrogen Test in an Open Space

2011 ◽  
Author(s):  
Hyung Seok Kang ◽  
Sang Baik Kim ◽  
Min-Hwan Kim ◽  
Hee Cheon No
Keyword(s):  
Flame Front ◽  
Flame Propagation ◽  
Spark Ignition ◽  
Cell Length ◽  
Cfd Analysis ◽  
Analysis Method ◽  
Step Size ◽  
Time Step ◽  
Time Step Size ◽  
Comparison Results

A computational fluid dynamics (CFD) calculation for a hydrogen explosion test with a complicated obstacle tube geometry of pitch 21.3mm and diameter 99.1mm at a stoichiometric condition was performed to establish a CFD analysis method for a hypothetical hydrogen explosion accident between a very high temperature reactor (VHTR) and a hydrogen production facility. We developed a spark ignition model to simulate high ignition energy of 40J induced by an electric device for 2 ms in the hydrogen explosion based on an energy conservation law. We performed a sensitivity calculation by varying a constant value of the eddy dissipation model (EDM), a time step size, and a cell length size around the obstacle tube to evaluate an effect of each factor on the flame propagation and overpressure buildup phenomenon. The CFD results of the flame front time of arrival (TOA) and overpressure were compared with those of the test data. The comparison results showed that the spark ignition model with a radius of 6 cm, a pressure of 105.7 kPa, a temperature of 1000 K, a turbulent mixing time of 2 ms, and an assumption of the 10% product mass fraction can reasonably initiate the hydrogen flame propagation in the CFD calculation. As for the CFD analysis method, the EDM constants of A = 10 and B = 0.8, the time step size of 0.01 ms, the cell length of 1 cm around the obstacle tube predicted the measured flame front TOA and peak overpressure with an error range of about 27.8% and 53.3%, respectively. Therefore, it is known that the CFD analysis with the EDM may be used as an accurate evaluation tool to provide the 3-dimesnional information of the flame front TOA and overpressure buildup phenomenon if the CFD analysis method is properly chosen.

Impacts of Spark Discharge Current and Duration on Flame Development of Lean Mixtures Under Flow Conditions

2018 ◽  
Author(s):  
Zhenyi Yang ◽  
Xiao Yu ◽  
Shui Yu ◽  
Jianming Chen ◽  
Guangyun Chen ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Discharge Current ◽  
Propagation Speed ◽  
Spark Ignition ◽  
Spark Discharge ◽  
Current Level ◽  
Ignition Process ◽  
Flame Kernel ◽  
Flame Development ◽  
Discharge Duration

Lean or diluted combustion has been considered as an effective strategy to improve the thermal efficiency of spark ignition engines. Under lean or diluted conditions, the combustion speed is reduced by the diluting gas. In order to speed up the combustion, in-cylinder flow is intentionally enhanced to promote the flame propagation. However, it is observed that the flow may make the spark ignition process more challenging due to the shortened discharge duration, the frequent re-strikes of spark plasma and the more complicated interactions between the flow and the flame. In this research, the effects of spark discharge current level and discharge duration on flame kernel development and flame propagation of lean methane air mixture are investigated under flow velocity of about 25 m/s and background pressure of 4 bar abs in an optical combustion chamber. A dual coil ignition system and an in-house developed current management module are used to create different discharge current levels. The average discharge current levels range from 55 mA, 190 mA, up to 250 mA. Detached flame kernel is observed under some test conditions. The flame propagation speed with the detached flame is generally slower than the flame developed from a flame kernel attached to the spark plug. The flame detachment is related to both the discharge current level and the discharge duration. When the discharge current level is high at 250 mA, the detached flame is observed at shorter discharge duration of 0.8 ms, while when the discharge current is low at 190 mA, detached flame can happen at longer discharge duration of 1.3 ms. Various discharge current and discharge durations are adopted to initiate the combustion in a single-cylinder engine operating with lean gasoline air mixture. It is shown from the results that a higher discharge current level and longer discharge duration are beneficial for controlling the combustion phasing and improving the operation stability of the engine.

A Numerical Simulation of Analysis of Backfiring Phenomena in a Hydrogen Fuelled Spark Ignition Engine

2015 ◽  
Author(s):  
K. A. Subramanian ◽  
B. L. Salvi
Keyword(s):  
Hot Spot ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Intake Manifold ◽  
Injection Timing ◽  
Ignition Process ◽  
Si Engine ◽  
Engine Operation ◽  
Study Results ◽  
Residual Gas

Hydrogen utilization in spark ignition engines could reduce urban pollution including particulate matter as well as greenhouse gas (carbon dioxide) emission. However, backfiring, which is an undesirable combustion process of intake charge in hydrogen fuelled spark ignition (SI) engine with manifold based injection, is one of the major technical issues in view of safety as well as continuous engine operation as ignition process could proceed instantaneously due to less ignition energy requirement of hydrogen. Backfiring occurs generally during suction stroke as the hydrogen-air charge interacts with residual gas resulting in flame growth and propagation towards upstream of engine’s intake manifold resulting in stalling of engine operation and high risk of safety. This work is aimed at analysis of backfiring in a hydrogen fuelled SI engine. The results indicate that backfiring is mainly function of residual gas temperature, start of hydrogen injection timing and equivalence ratio. Any hot-spot present in the cylinder would act as ignition source resulting in more chances of backfiring. In addition to this, CFD analysis was carried out in order to assess flow characteristics of hydrogen and air during suction stroke in intake manifold. Furthermore, numerical analysis of intake charge velocity, flame speed (deflagration), and flame propagation (backfiring) towards upstream of intake manifold was also carried out. Some notable points of backfiring control strategy including exhaust gas recirculation (EGR) and retarded (late) hydrogen injection timing are emerged from this study for minimizing chance of backfiring. This study results are useful for development of dedicated spark ignition engine for hydrogen fuel in the aspects of elimination of backfiring.

Experimental Setup of Combustion Visualization Inside a Heavy-Duty Diesel Engine Converted to Natural-Gas Spark-Ignition Operation

2019 ◽  
Author(s):  
Vishnu Padmanaban ◽  
Jinlong Liu ◽  
Cosmin E. Dumitrescu
Keyword(s):  
Diesel Engine ◽  
Natural Gas ◽  
Flame Propagation ◽  
Combustion Process ◽  
Spark Ignition ◽  
Experimental Setup ◽  
Engine Operation ◽  
Spark Plug ◽  
Efficient Combustion ◽  
Heavy Duty Diesel

Abstract The conversion of existing diesel engines to natural-gas (NG) spark-ignition (SI) operation would reduce U.S. dependence on oil imports and curtail greenhouse gas emissions. As the literature shows that the combustion process in such converted engines is different compared to that in conventional SI engines, understanding the effects of the diesel geometry and fuel effects on the in-cylinder flame propagation is important for optimizing engine operation. This paper describes the experimental setup that allowed the visualization of combustion phenomena inside a single-cylinder diesel engine converted to single-fuel NG spark-ignition operation through the addition of a spark plug and a low-pressure gas injector. The synchronization between the piston position and image acquisition was done using over-the-counter electronic components. While the setup could not visualize flame propagation inside the squish region, the combustion images, together with the pressure-based analysis, help understand the characteristics of lean NG flame propagation inside a diesel geometry, which is an important for designing a highly-efficient combustion process.

Combustion development in a gasoline-fueled spark ignition–controlled auto-ignition engine operated at different spark timings and intake air temperatures

2019 ◽  
pp. 146808741989416
Author(s):  
Melih Yıldız ◽  
Bilge Albayrak Çeper
Keyword(s):  
Flame Propagation ◽  
Mass Fraction ◽  
Transition Point ◽  
Combustion Process ◽  
Spark Ignition ◽  
Engine Operation ◽  
Air Temperatures ◽  
Auto Ignition ◽  
Crank Angle ◽  
Flame Development

Spark ignition–controlled auto-ignition is a combustion strategy to overcome the challenges in a homogeneous charge compression ignition or controlled auto-ignition combustion which has a limited operation region and does not have any direct control of the combustion timing. However, the spark ignition–controlled auto-ignition combustion can result in a large cyclic variability due to two main distinctive combustion phases developing initially by flame propagation and following controlled auto-ignition combustion throughout an engine cycle. Characterization of combustion development is, therefore, required to maintain a stable engine operation under spark ignition–controlled auto-ignition combustion. In this research, experimental studies were carried out to investigate spark ignition–controlled auto-ignition combustion development at different spark advances and intake air temperatures. Combustion analyses were performed employing pressure-based heat release and mass fraction burn curve to determine the main combustion parameters along with transition points (corresponding to crank angles) to controlled auto-ignition and mass fraction burnt by flame propagation. The results reveal that transition point has a strong correlation with crank angle position where 10% of fuel mass consumed combustion phasing rather than mass fraction burnt by flame propagation at the same intake air temperature. The cycles with a higher mass fraction burnt by flame propagation can result from early flame development at the advanced spark timings (at −30 and −40 °CA) while the slow flame development at a spark timing of −20 °CA due to late transition point corresponding to crank angle occurred. Besides, it is also found that flame propagation phase more contributes to the cyclic variation in the whole combustion process.

scholarly journals Numerical Modeling of Spark Ignition in Internal Combustion Engines

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Rafał Pyszczek ◽  
Jooyoung Hahn ◽  
Peter Priesching ◽  
Andrzej Teodorczyk
Keyword(s):  
Internal Combustion Engines ◽  
Engine Performance ◽  
Spark Ignition ◽  
Electrical Circuit ◽  
Heat Diffusion ◽  
Combustion Model ◽  
Ignition Process ◽  
Discharge Process ◽  
Proposed Model ◽  
Spark Channel

Abstract In this paper, we aim to develop a comprehensive ignition model for three-dimensional (3D) computational fluid dynamics (CFD) combustion modeling in spark-ignited (SI) engines. In the proposed model, we consider the following aspects separately to model the spark ignition process comprehensively. An electrical circuit is solved for calculation of the energy transferred to the spark plasma channel. The spark itself is represented by computational particles for monitoring its motion and ignitability. Heat diffusion from the spark toward the surrounding mixture is calculated with a one-dimensional (1D) model, resulting in the temperature obtained at the surface of the spark channel. Based on the calculated temperature and interpolated pressure and local mixture composition, an instantaneous ignition delay time is read from tabulated values for every particle representing the spark channel. The final ignitability criterion is defined by a precursor calculated with a zero-dimensional (0D) model, which accounts for the history of changes in spark surface temperature and local mixture properties. As soon as the precursor reaches a threshold value for a given spark channel particle, a flame kernel is introduced at a position of the particle. Flame propagation is generally treated by the G-equation combustion model. Validation is performed by measurements of the spark discharge process in high-velocity flow field and single-cylinder AVL research engine. We demonstrate that the proposed model can correctly reproduce the electrical circuit, spark channel dynamics, and overall engine performance.

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