CFD Modeling of Pilot Injection and EGR in DI Diesel Engines

2004 ◽  
Author(s):  
Arturo de Risi ◽  
Teresa Donateo ◽  
Domenico Laforgia
Keyword(s):  
Shell Model ◽  
Diesel Engines ◽  
Direct Injection ◽  
Operating Conditions ◽  
Spray Angle ◽  
Cfd Modeling ◽  
Pilot Injection ◽  
Wide Range ◽  
Combustion Processes ◽  
Injection Strategies

The simulation of direct injection diesel engines requires accurate models to predict spray evolution and combustion processes. Several models have been proposed and widely tested for traditional injection strategies characterized by single injection pulse close to top dead center. Unfortunately, these models show some limits when applied to different injection strategies so that a correct simulation of engine performances and emission cannot be achieved without changing variables included in spray and combustion models. The aim of the present investigation is to improve the prediction capability of the KIVA3V code in case of pilot injection in order to use numerical simulations to define optimized pilot injection strategies. This goal was achieved by eliminating the hypotheses of constant fuel density and constant spray angle in the KIVA3V code and by using a modified version of the Shell model. The proposed modifications to the Shell model allow a better description of low temperature kinetics by the addition of two more radicals and three new kinetics reactions. The improvements in the code were verified by comparing experimental data and numerical results over a wide range of operating conditions including single injections, pilot injections and EGR.

Evaluation of a Cyclone-Based Particulate Filtration System for High-Speed Diesel Engines

1994 ◽  
Vol 208 (4) ◽  
pp. 269-279 ◽  
Author(s):  
C Arcoumanis ◽  
L N Barbaris ◽  
R I Crane ◽  
P Wisby
Keyword(s):  
Diesel Engines ◽  
High Speed ◽  
Direct Injection ◽  
Operating Conditions ◽  
Exhaust Pipe ◽  
Filtration System ◽  
High Speed Diesel ◽  
Wide Range ◽  
Mass Flowrate ◽  
Particulate Filtration

A cyclone-based filtration system has been developed and its potential for reduction of exhaust particulates in high-speed direct injection diesel engines is evaluated; the filtration efficiency of the four cyclones has been enhanced by means of particulate agglomeration induced by cooling in a heat exchanger. With this system installed in the exhaust pipe of a 2.5 litre direct injection engine, tests covering a wide range of speed, load and exhaust gas recirculation (EGR) fraction resulted in reductions of up to 77 per cent in emitted particulate mass flowrate. The dependence of the system's performance on engine operating conditions, EGR configuration and cyclone geometry is presented and discussed.

Validating the Phenomenological Smoke Model at Different Operating Conditions of DI Diesel Engines

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Y. V. Aghav ◽  
P. A. Lakshminarayanan ◽  
M. K. G. Babu ◽  
Azeem Uddin ◽  
A. D. Dani
Keyword(s):  
Diesel Engines ◽  
Direct Injection ◽  
Operating Conditions ◽  
Low Velocity ◽  
Engine Operation ◽  
Wide Range ◽  
Wall Impingement ◽  
Nozzle Hole ◽  
Wall Interaction ◽  
Geometrical Consideration

A new phenomenological model that was published in Aghav et al. (2005, “Phenomenology of Smoke From Direct Injection Diesel Engines,” Proceedings of ICEF2005, ASME Paper No. 1350) encompasses the spray and the wall interaction by a simple geometrical consideration. The current study extends this earlier work with investigations made on 16 different engines from six-engine families of widely varying features, applied to off-highway as well as on-road duty. A dimensionless factor was introduced to take care of the nozzle hole manufactured by hydroerosion, as well as the conical shape of the nozzle hole (k factor) in the case of valve-closed-orifice type of nozzles. The smoke emitted from the wall spray formed after wall impingement is the major contributor to the total smoke at higher loads. As the fuel spray impinges upon the walls of the combustion chamber, its velocity decreases. This low-velocity jet contributes to the higher rate of the smoke production. Therefore, the combustion bowl geometry along with injection parameters play a significant role in the smoke emissions. The new model is one dimensional and based on the recent phenomenological description of spray combustion in a direct injection diesel engine. The satisfactory comparison of the predicted and observed smoke over the wide range of engine operation demonstrated applicability of the model in simulation study of combustion occurring in direct injection (DI) diesel engines.

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.

An Investigation of the Sources of Blowby in Single-Cylinder Supercharged Diesel Engines

1978 ◽  
Vol 192 (1) ◽  
pp. 39-48 ◽  
Author(s):  
B. Bull ◽  
M. A. Voisey
Keyword(s):  
Carbon Dioxide ◽  
Diesel Engines ◽  
Piston Ring ◽  
Carbon Dioxide Concentration ◽  
Operating Conditions ◽  
Exhaust Valve ◽  
Simple Method ◽  
Single Cylinder ◽  
Carbon Dioxide Concentrations ◽  
Wide Range

Measurements of carbon dioxide concentrations in the exhaust and in the crankcase of two different types of single-cylinder, supercharged diesel engines have been used to determine the amount of exhaust gas reaching the crankcase as piston ring blowby and as leakage through the exhaust valve stem-to-guide clearance. Over a wide range of operating conditions in both engines the carbon dioxide concentration was found to be more dependent on engine fuelling rate per hour than on fuel input per stroke. It was established that blowby through the exhaust valve guide was a major contributor to crankcase contamination. A simple method has been devised, requiring only minor modifications to the engine, that permits the blowby through the piston ring pack and the exhaust valve guides to be determined separately in turbocharged production engines.

scholarly journals Optical Characterization of a Multipoint Lean Direct Injector for Gas Turbine Combustors: Velocity and Fuel Drop Size Measurements

2010 ◽  
Author(s):  
Christopher M. Heath ◽  
Yolanda R. Hicks ◽  
Robert C. Anderson ◽  
Randy J. Locke
Keyword(s):  
Gas Turbine ◽  
Drop Size ◽  
Fuel Injection ◽  
Direct Injection ◽  
Operating Conditions ◽  
Diagnostic Methods ◽  
Spray Angle ◽  
Fuel Injector ◽  
Flame Tube ◽  
Component Velocity

Performance of a multipoint, lean direct injection (MP-LDI) strategy for low emission aero-propulsion systems has been tested in a Jet-A fueled, lean flame tube combustion rig. Operating conditions for the series of tests included inlet air temperatures between 672 K and 828 K, pressures between 1034 kPa and 1379 kPa and total equivalence ratios between 0.41 and 0.45, resulting in equilibrium flame temperatures approaching 1800 K. Ranges of operation were selected to represent the spectrum of subsonic and supersonic flight conditions projected for the next-generation of commercial aircraft. This document reports laser-based measurements of in situ fuel velocities and fuel drop sizes for the NASA 9-point LDI hardware arranged in a 3 × 3 square grid configuration. Data obtained represent a region of the flame tube combustor with optical access that extends 38.1-mm downstream of the fuel injection site. All data were obtained within reacting flows, without particle seeding. Two diagnostic methods were employed to evaluate the resulting flow path. Three-component velocity fields have been captured using phase Doppler interferometry (PDI), and two-component velocity distributions using planar particle image velocimetry (PIV). Data from these techniques have also offered insight into fuel drop size and distribution, fuel injector spray angle and pattern, turbulence intensity, degree of vaporization and extent of reaction. This research serves to characterize operation of the baseline NASA 9-point LDI strategy for potential use in future gas-turbine combustor applications. An additional motive is the compilation of a comprehensive database to facilitate understanding of combustor fuel injector aerodynamics and fuel vaporization processes, which in turn may be used to validate computational fluid dynamics codes, such as the National Combustor Code (NCC), among others.

A New Predictive ID Model for Advanced High Speed Direct Injection Diesel Engines

2004 ◽  
Author(s):  
Lurun Zhong ◽  
Naeim A. Henein ◽  
Walter Bryzik
Keyword(s):  
Diesel Engines ◽  
High Speed ◽  
Direct Injection ◽  
Combustion Process ◽  
Operating Conditions ◽  
Injection System ◽  
Injection Timing ◽  
Common Rail Injection System ◽  
Common Rail Injection ◽  
Starting Conditions

Advance high speed direct injection diesel engines apply high injection pressures, exhaust gas recirculation (EGR), injection timing and swirl ratios to control the combustion process in order to meet the strict emission standards. All these parameters affect, in different ways, the ignition delay (ID) which has an impact on premixed, mixing controlled and diffusion controlled combustion fractions and the resulting engine-out emissions. In this study, the authors derive a new correlation to predict the ID under the different operating conditions in advanced diesel engines. The model results are validated by experimental data in a single-cylinder, direct injection diesel engine equipped with a common rail injection system at different speeds, loads, EGR ratios and swirl ratios. Also, the model is used to predict the performance of two other diesel engines under cold starting conditions.

scholarly journals Effect of Injection Strategies in Diesel/NG Direct-Injection Engines on the Combustion Process and Emissions under Low-Load Operating Conditions

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 990 ◽  
Author(s):  
Jinze Li ◽  
Longfei Deng ◽  
Jianjun Guo ◽  
Min Zhang ◽  
Zhenyuan Zi ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Direct Injection ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Operating Conditions ◽  
Diffusion Combustion ◽  
Combustion Mode ◽  
Low Load ◽  
Hc Emissions ◽  
Injection Strategies

The direct injection of natural gas (NG), which is an important research direction in the development of NG engines, has the potential to improve thermal efficiency and emissions. When NG engines operate in low-load conditions, combustion efficiency decreases and hydrocarbon (HC) emissions increase due to lean fuel mixtures and slow flame propagation speeds. The effect of two combustion modes (partially premixed compression ignition (PPCI) and high pressure direct injection (HPDI)) on combustion processes was investigated by CFD (Computational Fluid Dynamics), with a focus on different injection strategies. In the PPCI combustion mode, NG was injected early in the compression stroke and premixed with air, and then the pilot diesel was injected to cause ignition near the top dead center. This combustion mode produced a faster heat release rate, but the HC emissions were higher, and the combustion efficiency was lower. In the HPDI combustion mode, the diesel was injected first and ignited, and then the NG was injected into the flame. This combustion mode resulted in higher emissions of NOx and soot, with a diffusion combustion in the cylinder. HC emissions significantly decreased. Compared with PPCI combustion, HPDI had a higher thermal efficiency.

Modeling heavy-duty diesel engines using tabulated kinetics in a wide range of operating conditions

2020 ◽  
pp. 146808741989616 ◽  
Author(s):  
Qiyan Zhou ◽  
Tommaso Lucchini ◽  
Gianluca D’Errico ◽  
Gilles Hardy ◽  
Xingcai Lu
Keyword(s):  
Diesel Engines ◽  
Operating Conditions ◽  
Scalar Dissipation ◽  
Cylinder Pressure ◽  
Heavy Duty ◽  
Variable Model ◽  
Progress Variable ◽  
Wide Range ◽  
Heavy Duty Diesel ◽  
Operating Points

Fast and high-fidelity combustion models including detailed kinetics and turbulence chemistry interaction are necessary to support design and development of heavy-duty diesel engines. In this work, the authors intend to present and validate tabulated flamelet progress variable model based on tabulation of laminar diffusion flamelets for different scalar dissipation rate, whose predictability highly depends on the description of fuel–air mixing process in which engine mesh layout plays an important role. To this end, two grids were compared and assessed: in both grids, cells were aligned on the spray direction with such region being enlarged in the second one, where the near-nozzle and near-wall mesh resolution were also improved, which is expected to better account for both spray dynamics and flame–wall interaction dominating the combustion process in diesel engines. Flame structure, in-cylinder pressure, apparent heat release rate, and emissions for different relevant operating points were compared and analyzed to identify the most suitable mesh. Afterwards, simulations were carried out in a heavy-duty engine considering 20 operating points, allowing to comprehensively verify the validity of tabulated flamelet progress variable model. The results demonstrated that the proposed approach was capable to accurately predict in-cylinder pressure evolution and NO x formation across a wide engine map.

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