Effect of Piston Crevices on the Numerical Simulation of a Heavy-Duty Diesel Engine Retrofitted to Natural-Gas Spark-Ignition Operation

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Iolanda Stocchi ◽  
Jinlong Liu ◽  
Cosmin Emil Dumitrescu ◽  
Michele Battistoni ◽  
Carlo Nazareno Grimaldi
Keyword(s):  
Heat Release ◽  
Fuel Injection ◽  
Combustion Engine ◽  
Direct Injection ◽  
Three Dimensional ◽  
Spark Ignition ◽  
Combustion Model ◽  
Heavy Duty ◽  
Compression Ignition Engine ◽  
Heavy Duty Diesel

Three-dimensional computational fluid dynamics internal combustion engine simulations that use a simplified combustion model based on the flamelet concept provide acceptable results with minimum computational costs and reasonable running times. Moreover, the simulation can neglect small combustion chamber details such as valve crevices, valve recesses, and piston crevices volume. The missing volumes are usually compensated by changes in the squish volume (i.e., by increasing the clearance height of the model compared to the real engine). This paper documents some of the effects that such an approach would have on the simulated results of the combustion phenomena inside a conventional heavy-duty direct injection compression-ignition engine, which was converted to port fuel injection spark ignition operation. Numerical engine simulations with or without crevice volumes were run using the G-equation combustion model. A proper parameter choice ensured that the numerical results agreed well with the experimental pressure trace and the heat release rate. The results show that including the crevice volume affected the mass of a unburned mixture inside the squish region, which in turn influenced the flame behavior and heat release during late-combustion stages.

Effect of Piston Crevices on 3D Simulation of a Heavy-Duty Diesel Engine Retrofitted to Natural Gas Spark Ignition

2018 ◽  
Author(s):  
Iolanda Stocchi ◽  
Jinlong Liu ◽  
Cosmin E. Dumitrescu ◽  
Michele Battistoni ◽  
Carlo Nazareno Grimaldi
Keyword(s):  
Fuel Injection ◽  
Direct Injection ◽  
Combustion Model ◽  
Heavy Duty ◽  
Ic Engine ◽  
Pressure Trace ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel ◽  
Flame Behavior ◽  
Experimental Pressure

3D CFD IC engine simulations that use a simplified combustion model based on the flamelets concept can provide acceptable results with minimum computational costs and reasonable running times. More, the simulation can neglect small combustion chamber details such as valve crevices, valve recesses and piston crevices volume. The missing volumes are usually compensated by changes in the squish volume (i.e., by increasing the clearance height of the model compared to the real engine). This paper documents some of the effects that such an approach would have on the simulated results of the combustion phenomena inside a conventional heavy-duty direct-injection CI engine, which was converted to port-fuel injection SI operation. 3D IC engine simulations with or without crevice volumes were run using the G-equation combustion model. A proper parameter choice ensured that the simulation results agreed well with the experimental pressure trace. The results show that including the crevice volume affected the mass of unburned mixture inside the squish region, which in turn influenced the flame behavior and heat release during late-combustion stages.

A CFD Study on Heavy Duty DI Diesel Engine to Achieve Ultra-Low Emissions

2010 ◽  
Author(s):  
M. Yilmaz ◽  
H. Koten ◽  
M. Zafer Gul
Keyword(s):  
Diesel Engine ◽  
Cfd Simulation ◽  
Combustion Engine ◽  
Direct Injection ◽  
Spray Angle ◽  
Combustion Model ◽  
Multiphase Model ◽  
Heavy Duty ◽  
Start Of Injection ◽  
Main Injection

Nowadays, automotive industries focused on clean diesel combustion in their combustion processes are investigated for their potential to achieve near zero particulate and NOx (Nitrogen oxides) emissions. Their main disadvantages are increased level of unburned hydrocarbons (HC) and carbon monoxide (CO) emissions, combustion control at high load, power output and limited operating range. The simulation of the air flow, spray and combustion in an internal combustion engine were prepared for a single cylinder of a nine-liter, six cylinder diesel engine. Many times the geometry is complex because moving pistons and valves are involved, which makes it difficult to generate structured mesh. In-cylinder spray-air motion interaction, a Lagrangian multiphase model has been applied in a heavy-duty CI engine under direct injection conditions. A comprehensive model for atomization of liquid sprays under high injection pressures has been employed. Three dimensional CFD calculations of the intake, compression and power strokes have been carried out with different spray angle, spray profile and start of injection. A new combustion model ECFM-3Z (Extended Coherent Flame Model) developed at IFP is used for combustion modeling. Finally, a calculation on an engine configuration with compression, spray injection and combustion in a direct injection Diesel engine is presented. In this study, exhaust emissions, and particularly the emission of NOx, CO and soot derived from premixed combustion are investigated, and the relationship between combustion and emission characteristics are showed. The calculated CFD simulation in different combustion cases was compared. The cases were prepared by changing the parameters: start of injection, spray angle and spray profile. Modeling of combustion proposed in the present study can be outlined as follows. NOx concentration is decreased by combustion of a over lean-mixture modeled by the pre-injection. Most of pre-mixture is combusted by main-injection, and therefore the amount of pre-injection and main-injection come into prominence. The results are greatly in agreement qualitatively with the previous experimental and computational studies in the literature.

Three-Dimensional Simulation of Gaseous Fuel Injection Through a Hybrid Approach

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
L. Andreassi ◽  
A. L. Facci ◽  
S. Ubertini
Keyword(s):  
Fuel Injection ◽  
Combustion Engine ◽  
Direct Injection ◽  
Hybrid Approach ◽  
Three Dimensional ◽  
Air Entrainment ◽  
Gaseous Fuel ◽  
Injection System ◽  
Injection Process ◽  
Dimensional Simulation

Direct injection of gaseous fuel has emerged to be a high potential strategy to tackle both environmental and fuel economy requirements. However, since the electronic gaseous injection technology is rather new for automotive applications, limited experience exists on the optimum configuration of the injection system and the combustion chamber. To facilitate the development of these applications computer models are being developed to simulate gaseous injection, air entrainment, and the ensuing combustion. This paper introduces a new method for modeling the injection process of gaseous fuels in multidimensional simulations. The proposed model allows holding down grid requirements, thus, making it compatible with the three-dimensional simulation of an internal combustion engine.

CFD and Optical Investigations of Fluid Dynamics and Mixture Formation in a DI-H2ICE

2010 ◽  
Author(s):  
Riccardo Scarcelli ◽  
Thomas Wallner ◽  
Hermann Obermair ◽  
Victor M. Salazar ◽  
Sebastian A. Kaiser
Keyword(s):  
Mole Fraction ◽  
Fuel Injection ◽  
Combustion Engine ◽  
Direct Injection ◽  
Three Dimensional ◽  
Symmetry Plane ◽  
Injection Velocity ◽  
Compression Stroke ◽  
Commercial Code ◽  
Wall Interaction

This paper reports the validation of a three-dimensional numerical simulation of the in-cylinder processes during gas-exchange, injection, and compression in a direct-injection, hydrogen-fueled internal combustion engine. Computational results from the commercial code Fluent are compared to experimental data acquired by laser-based measurements in a corresponding optically accessible engine. The simulation includes the intake-port geometry as well as the injection event with its supersonic hydrogen jet. The cylinder geometry is typical of passenger-car sized spark-ignited engines. Gaseous hydrogen is injected from a high-pressure injector with a single-hole nozzle. Numerically and experimentally determined flow fields in the vertical, central symmetry plane are compared for a series of crank angles during the compression stroke, with and without fuel injection. With hydrogen injection, the fuel mole-fraction in the same data plane is included in the comparison as well. The results show that the simulation predicts the flow field without injection reasonably well, with increasing numerical-experimental disagreement towards the end of the compression stroke. The injection event completely disrupts the intake-induced flow, and the simulation predicts the post-injection velocity fields much better than the flow without injection at the same crank-angles. The two-dimensional tumble ratio is evaluated to quantify the coherent barrel motion of the charge. Without fuel injection, the simulation significantly over-predicts tumble during most of the compression stroke, but with injection, the numerical and experimental tumble ratio track each other closely. The evolution of hydrogen mole-fraction during the compression stroke shows conflicting trends. Jet penetration and jet-wall interaction are well captured, while fuel dispersion appears under-predicted. Possible causes of this latter discrepancy are discussed.

Combustion Model for a Homogeneous Turbocharged Gasoline Direct-Injection Engine

2017 ◽  
Author(s):  
Sedigheh Tolou ◽  
Ravi Teja Vedula ◽  
Harold Schock ◽  
Guoming Zhu ◽  
Yong Sun ◽  
...  
Keyword(s):  
Experimental Data ◽  
Heat Release ◽  
Fuel Injection ◽  
Direct Injection ◽  
Local Maximum ◽  
Gasoline Direct Injection ◽  
Combustion Model ◽  
Engine Operation ◽  
Gdi Engine ◽  
Mean Square Errors

Homogeneous charge is a preferred operation mode of gasoline direct-injection (GDI) engines. However, a limited amount of work exists in the literature for combustion models of this mode of engine operation. Current work describes a model developed and used to study combustion in a GDI engine having early intake fuel injection. The model was validated using experimental data obtained from a 1.6L Ford EcoBoost® four-cylinder engine, tested at the U.S. EPA. The start of combustion was determined from filtered cycle-averaged cylinder pressure measurements, based on the local maximum of third derivative with respect to crank angle. The subsequent heat release, meanwhile, was approximated using a double-Wiebe function, to account for the rapid initial pre-mixed combustion (stage 1) followed by a gradual diffusion-like state of combustion (stage 2) as observed in this GDI engine. A non-linear least-squares optimization was used to determine the tuning variables of Wiebe correlations, resulting in a semi-predictive combustion model. The effectiveness of the semi-predictive combustion model was tested by comparing the experimental in-cylinder pressures with results obtained from a model built using a one-dimensional engine simulation tool, GT-POWER (Gamma Technologies). Model comparisons were made for loads of 60, 120, and 180 N-m at speeds ranging from 1500 to 4500 rpm, in 500 rpm increments. The root-mean-square errors between predicted cylinder pressures and the experimental data were within 2.5% of in-cylinder peak pressure during combustion. The semi-predictive combustion model, verified using the GT-POWER simulation, was further studied to develop a predictive combustion model. The performance of the predictive combustion model was examined by regenerating the experimental cumulative heat release. The heat release analysis developed for the GDI engine was further applied to a dual mode, turbulent jet ignition (DM-TJI) engine. DM-TJI is an advanced combustion technology with a promising potential to extend the thermal efficiency of spark ignition engines with minimal engine-out emissions. The DM-TJI engine was observed to offer a faster burn rate and lower in-cylinder heat transfer when compared to the GDI engine under the same loads and speeds.

Thermodynamic Modeling of Single Cylinder Direct Injection Compression Ignition Engine in Simulink

2015 ◽  
Vol 813-814 ◽  
pp. 866-873
Author(s):  
Sindhu Ravichettu ◽  
G. Amba Prasad Rao ◽  
K. Madhu Murthy
Keyword(s):  
Heat Release ◽  
Direct Injection ◽  
Combustion Process ◽  
Combustion Model ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Close Match ◽  
Tuning Parameters ◽  
Crank Angle ◽  
Diesel Cycle

The aim of this research is to develop a mathematical model of a compression ignition engine using cylinder-by-cylinder model approach to predict the performances; indicated work, indicated torque, in-cylinder pressures and temperatures and heat release rates. The method used in the study is based on ideal diesel cycle and is modified by the numerical formulations which affect the performance of the engine. The model consists of a set of tuning parameters such as engine geometries, EGR fractions, boost pressures, injection timings, air/fuel ratio, etc. It is developed in Simulink environment to promote modularity. A single-zone combustion model is developed and implemented for the combustion process which accounts for ignition delay, heat release. Derivations from slider-crank mechanism are involved to compute the instantaneous volume, area and stroke at any given crank angle. The results of the simulation model have been validated with experimental results with a close match between them.

Experimental Investigation of a Heavy-Duty Compression-Ignition Engine Retrofitted to Natural Gas Spark-Ignition Operation

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Jinlong Liu ◽  
Hemanth Kumar Bommisetty ◽  
Cosmin Emil Dumitrescu
Keyword(s):  
Natural Gas ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Compression Ignition ◽  
Heavy Duty ◽  
Compression Ignition Engine ◽  
Engine Operation ◽  
Cycle Variation ◽  
Spark Timing ◽  
Ci Engines

Heavy-duty compression-ignition (CI) engines converted to natural gas (NG) operation can reduce the dependence on petroleum-based fuels and curtail greenhouse gas emissions. Such an engine was converted to premixed NG spark-ignition (SI) operation through the addition of a gas injector in the intake manifold and of a spark plug in place of the diesel injector. Engine performance and combustion characteristics were investigated at several lean-burn operating conditions that changed fuel composition, spark timing, equivalence ratio, and engine speed. While the engine operation was stable, the reentrant bowl-in-piston (a characteristic of a CI engine) influenced the combustion event such as producing a significant late combustion, particularly for advanced spark timing. This was due to an important fraction of the fuel burning late in the squish region, which affected the end of combustion, the combustion duration, and the cycle-to-cycle variation. However, the lower cycle-to-cycle variation, stable combustion event, and the lack of knocking suggest a successful conversion of conventional diesel engines to NG SI operation using the approach described here.

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