Effects of grid alignment on modeling the spray and mixing process in direct injection diesel engines under non-reacting operating conditions

2015 ◽  
Vol 91 ◽  
pp. 901-912 ◽  
Author(s):  
Amin Maghbouli ◽  
Tommaso Lucchini ◽  
Gianluca D'Errico ◽  
Angelo Onorati
Keyword(s):  
Diesel Engines ◽  
Direct Injection ◽  
Operating Conditions ◽  
Mixing Process

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.

Flow and Combustion in a Transparent 1.9 Litre Direct Injection Diesel Engine

1994 ◽  
Vol 208 (3) ◽  
pp. 191-205 ◽  
Author(s):  
C Arcoumanis ◽  
J H Whitelaw ◽  
W Hentschel ◽  
K-P Schindler
Keyword(s):  
Diesel Engines ◽  
Laser Diagnostics ◽  
Direct Injection ◽  
Computer Code ◽  
Operating Conditions ◽  
Auto Ignition ◽  
Sufficient Detail ◽  
Generating Capacity ◽  
Ignition And Combustion ◽  
Cylinder Flow

Two identical 1.9 litre direct injection (DI) diesel engines having optical access for application of laser diagnostics were operated at Volkswagen and Imperial College as part of the European programme (IDEA) on diesel engines. A variety of complementary laser-based techniques were used to characterize the flow-generating capacity of the intake system under steady flow conditions, the in-cylinder flow during induction and compression as well as the spray development, auto-ignition and combustion under three typical engine operating conditions. The most important results of this programme are presented and discussed here in view of their implications for improved combustion and reduction of exhaust emissions in small direct injection diesel engines, through better matching of the spray characteristics with the in-cylinder flow as a function of engine speed and load. The results were obtained in sufficient detail to allow validation of the multi-dimensional computer code developed within the IDEA programme.

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.

NOx emissions in direct injection diesel engines: Part 2: model performance for conventional, prolonged ignition delay, and premixed charge compression ignition operating conditions

2017 ◽  
Vol 19 (5) ◽  
pp. 528-541 ◽  
Author(s):  
Clemens Brückner ◽  
Panagiotis Kyrtatos ◽  
Konstantinos Boulouchos
Keyword(s):  
Diesel Engines ◽  
Ignition Delay ◽  
Direct Injection ◽  
Operating Conditions ◽  
Premixed Combustion ◽  
Nox Emission ◽  
Nox Emissions ◽  
Nox Formation ◽  
Parameter Variations ◽  
And Diffusion

Investigations from recent years have shown that at operating conditions characterized by long ignition delays and resulting large proportions of premixed combustion, the NOx emission trend does not correspond to the (usually) postulated correlation with an appropriately defined (adiabatic) burnt flame temperature. This correlation, however, is the cornerstone of most published NOx models for direct injection diesel engines. In this light, a new phenomenological NOx model has been developed in Brückner et al. (Part 1), which considers NOx formation from products of premixed and diffusion combustion and accounts for compression heating of post-flame gases, and describes NOx formation by thermal chemistry. In this study (Part 2), the model is applied to predict NOx emissions from two medium-speed direct injection diesel engines of different size and at various operating conditions. Single parameter variations comprising sweeps of injection pressure, start of injection, load, exhaust gas recirculation rate, number of injections, and end-of-compression temperature are studied on a single-cylinder engine. In addition, different engine configurations (valve timing, turbocharger setup) and injection parameters of a marine diesel engine are investigated. For both engines and all parameter variations, the model prediction shows good agreement. Most notably, the model captures the turning point of the NOx emission trend with increasing ignition delay (first decreasing, then increasing NOx) for both engines. The differentiation in the physical treatment of the products of premixed and diffusion with increasing ignition delay showed to be essential for the model to capture the trend-reversal. Specifically, the model predicted that peak NOx formation rates in diffusion zones decrease with increasing ignition delay, whereas for the same change in ignition delay, peak formation rates in premixed zones increase. This is caused by the high energy release in short time, causing a strong compression of existing premixed combustion product zones that mix at a slower rate and have less time to mix, significantly increasing their temperature. In contrast, the model under-predicts NOx emissions for very low oxygen concentrations, in particular below 15 vol.%, which is attributed to the simple thermal NOx kinetic mechanism used. It is concluded that the new model is able to predict NOx emissions for conventional diesel combustion and for long ignition delay operating conditions, where a substantial amount of heat is released in premixed mode.

Enhanced Splash Models for High Pressure Diesel Spray

2006 ◽  
Vol 129 (2) ◽  
pp. 609-621 ◽  
Author(s):  
L. Allocca ◽  
L. Andreassi ◽  
S. Ubertini
Keyword(s):  
Diesel Engines ◽  
Yttrium Aluminum Garnet ◽  
Second Harmonic ◽  
Laser Sheet ◽  
Direct Injection ◽  
Combustion Process ◽  
Numerical Data ◽  
Operating Conditions ◽  
Injection System ◽  
Correct Operation

Mixture preparation is a crucial aspect for the correct operation of modern direct injection (DI) Diesel engines as it greatly influences and alters the combustion process and, therefore, the exhaust emissions. The complete comprehension of the spray impingement phenomenon is a quite complete task and a mixed numerical-experimental approach has to be considered. On the modeling side, several studies can be found in the scientific literature but only in the last years complete multidimensional modeling has been developed and applied to engine simulations. Among the models available in literature, in this paper, the models by Bai and Gosman (Bai, C., and Gosman, A. D., 1995, SAE Technical Paper No. 950283) and by Lee et al. (Lee, S., and Ryou, H., 2000, Proceedings of the Eighth International Conference on Liquid Atomization and Spray Systems, Pasadena, CA, pp. 586–593; Lee, S., Ko, G. H., Ryas, H., and Hong, K. B., 2001, KSME Int. J., 15(7), pp. 951–961) have been selected and implemented in the KIVA-3V code. On the experimental side, the behavior of a Diesel impinging spray emerging from a common rail injection system (injection pressures of 80 and 120MPa) has been analyzed. The impinging spray has been lightened by a pulsed laser sheet generated from the second harmonic of a Nd-yttrium-aluminum-garnet laser. The images have been acquired by a charge coupled device camera at different times from the start of injection. Digital image processing software has enabled to extract the characteristic parameters of the impinging spray with respect to different operating conditions. The comparison of numerical and experimental data shows that both models should be modified in order to allow a proper simulation of the splash phenomena in modern Diesel engines. Then the numerical data in terms of radial growth, height and shape of the splash cloud, as predicted by modified versions of the models are compared to the experimental ones. Differences among the models are highlighted and discussed.

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.

scholarly journals Analysis of combustion performance and emission of extended expansion cycle and iEGR for low heat rejection turbocharged direct injection diesel engines

2014 ◽  
Vol 18 (1) ◽  
pp. 129-142 ◽  
Author(s):  
Mohd Shabir ◽  
Rajendra Prasath ◽  
P. Tamilporai
Keyword(s):  
Nitric Oxide ◽  
Diesel Engines ◽  
Thermal Efficiency ◽  
Direct Injection ◽  
High Heat ◽  
Operating Conditions ◽  
Blow Down ◽  
Heat Rejection ◽  
Performance And Emission ◽  
Combustion Performance

Increasing thermal efficiency in diesel engines through low heat rejection concept is a feasible technique. In LHR engines the high heat evolution is achieved by insulating the combustion chamber surfaces and coolant side of the cylinder with partially stabilized zirconia of 0.5 mm thickness and the effective utilization of this heat depend on the engine design and operating conditions. To make the LHR engines more suitable for automobile and stationary applications, the extended expansion was introduced by modifying the inlet cam for late closing of intake valve through Miller?s cycle for extended expansion. Through the extended expansion concept the actual work done increases, exhaust blow-down loss reduced and the thermal efficiency of the LHR engine is improved. In LHR engines, the formation of nitric oxide is more, to reduce the nitric oxide emission, the internal EGR is incorporated using modified exhaust cam with secondary lobe. Modifications of gas exchange with internal EGR resulted in decrease in nitric oxide emissions. In this work, the parametric studies were carried out both theoretically and experimentally. The combustion, performance and emission parameters were studied and were found to be satisfactory.

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.

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