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.

Enhanced Splash Models for High Pressure Diesel Sprays

2006 ◽  
Author(s):  
L. Allocca ◽  
L. Andreassi ◽  
S. Ubertini
Keyword(s):  
Diesel Engines ◽  
Second Harmonic ◽  
Laser Sheet ◽  
Combustion Process ◽  
Numerical Data ◽  
Ccd Camera ◽  
Operating Conditions ◽  
Injection System ◽  
Correct Operation ◽  
Common Rail Injection System

Mixture preparation is a crucial aspect for the correct operation of modern 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 to completely exploit the phenomenon 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 [1] and by Lee et al. [2, 3] 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 MPa and 120 MPa) has been analysed. The impinging spray has been lightened by a pulsed laser sheet generated from the second harmonic of a Nd-YAG laser. The images have been acquired by a CCD camera at different times from the start of injection (SOI). 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.

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.

Computational fluid dynamics study of the effects of the re-entrant lip shape and toroidal radii of piston bowl on a high-speed direct-injection diesel engine's performance and emissions

2005 ◽  
Vol 219 (8) ◽  
pp. 1011-1023 ◽  
Author(s):  
Y Zhu ◽  
H Zhao ◽  
N Ladommatos
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Fuel Injection ◽  
Direct Injection ◽  
Combustion Process ◽  
Operating Conditions ◽  
Injection System ◽  
Part Load ◽  
Piston Bowl

The piston bowl design is one of the most important factors that affect the air-fuel mixing and the subsequent combustion and pollutant formation processes in a direct-injection diesel engine. The bowl geometry and dimensions, such as the pip region, bowl lip area, and toroidal radius, are all known to have an effect on the in-cylinder mixing and combustion process. In order to understand better the effect of re-entrant geometry, three piston bowls with different toroidal radii and lip shapes were investigated using computational fluid dynamics engine modelling. KIVA3V with improved submodels was used to model the in-cylinder flows and combustion process, and it was validated on a high-speed direct-injection engine with a second-generation common-rail fuel injection system. The engine's performance, in-cylinder flow, and combustion, and emission characteristics were analysed at maximum power and maximum torque conditions and at part-load operating conditions. Three injector protrusions and injection timings were investigated at full-load and part-load conditions.

Fuzzy Logic Control of Diesel Combustion Phasing Using Ion Current Signal

2012 ◽  
Author(s):  
Tamer Badawy ◽  
Nassim Khaled ◽  
Naeim Henein
Keyword(s):  
Fuzzy Logic ◽  
Diesel Engines ◽  
Fuzzy Logic Controller ◽  
Combustion Process ◽  
Open Loop ◽  
Operating Conditions ◽  
Ion Current ◽  
Injection System ◽  
Loop Control ◽  
Engine Life

Diesel engines have to meet stringent emissions standards without penalties in performance and fuel economy. This necessitated the use of elaborate after treatment devices to reduce the tail pipe emissions. In order to decrease the demand on the after treatment devices, there is a need to reduce the emissions in the formation stage during combustion. This requires a precise control of the phasing of the combustion process. Currently, diesel engines are controlled by pre-set open loop schedules that require extensive, time consuming and costly laboratory tests and calibration tasks to meet the production target goals which are stricter than the emission standards. Such goals are set as a safe guard against the deterioration during engine life cycle. This paper presents an incremental fuzzy logic controller that adjusts the combustion phasing as per desired targets to meet production goals over the engine life period. An ion current/ glow plug sensor and its circuit are used to produce a signal indicative of different combustion parameters. Signal conditioning and filtering are applied to improve the quality of ion current. The algorithm developed in this paper optimizes the ion current feed back to increase its reliability for stable engine control while maintaining fast controller response, and high accuracy. Experiments are carried out on a four cylinder, turbo-charged, 4.5L heavy duty diesel engine equipped with a common rail injection system and an open ECU. The response of the controller is evaluated from experimental data obtained by running the engine under different steady, and transient operating conditions. The results demonstrate the ability of the closed-loop control system in achieving the desired combustion phasing.

Experimental Validation for Control-Oriented Modeling of Multi-Cylinder HCCI Diesel Engines

2006 ◽  
Author(s):  
Marcello Canova ◽  
Shawn Midlam-Mohler ◽  
Yann Guezennec ◽  
Giorgio Rizzoni ◽  
Luca Garzarella ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Diesel Engines ◽  
Soot Formation ◽  
Direct Injection ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Injection System ◽  
Compression Ignition ◽  
Mixture Formation ◽  
Hcci Combustion

Homogeneous Charge Compression Ignition (HCCI) is a combustion process based on a lean, homogeneous, premixed charge reacting and burning uniformly throughout the mixture volume. This principle leads to a consistent decrease in NOx and PM emissions, while the combustion efficiency remains comparable to traditional Compression Ignition Direct Injection (CIDI) engines at low and mid-load operations. However, understanding and controlling the combustion process is still extremely difficult, as well as finding a proper method for the fuel introduction. A viable method consists of premixing the charge by applying a proper fuel atomization device in the intake port, thus decoupling the HCCI mixture formation from the traditional in-cylinder injection. This avoids the traditional drawbacks associated to external Diesel mixture preparation, such as high intake heating, low compression ratio, wall wetting, and soot formation. The system, previously developed and tested on a single-cylinder engine, has been successfully applied to multi-cylinder Diesel engine for automotive applications. Building on previous modeling and experimental work, the paper reports a detailed experimental analysis of HCCI combustion with external mixture formation. In the considered testing setup, the fuel atomizer has been applied to a four-cylinder turbo-charged Common Rail Diesel engine equipped with a cooled EGR system. In order to extend the knowledge on the process and to provide a large base of data for the identification of Control-Oriented Models, Diesel-fueled HCCI combustion has been characterized over different values of loads, EGR dilution and boost pressures. The data collected were then used for the validation of a HCCI Diesel engine model that was previously built for steady state and transient simulation and for control purposes. The experimental results obtained, especially considering the emission levels and efficiency, suggest that the technology developed for external mixture formation is a feasible upgrade for automotive Diesel engines without introducing additional design efforts or constraints on the DI combustion and injection system.

Zero-Dimensional Analysis of Combustion in a Multiple-Injection CRDI Engine Using Wiebe Law

2015 ◽  
Vol 787 ◽  
pp. 707-711 ◽  
Author(s):  
G. Sudarshan ◽  
S. Rajkumar
Keyword(s):  
Engine Speed ◽  
Direct Injection ◽  
Combustion Process ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Common Rail ◽  
Injection System ◽  
Empirical Constant ◽  
Rate Law ◽  
Burn Rate

Common rail direct injection system (CRDI) offers the potential to achieve optimal combustion and emission characteristics. An empirical analysis of engine combustion process incorporating Wiebe type burn rate law approach is useful not only in understanding the combustion characteristics of a CRDI engine but also aids in diagnosis and control of the combustion process wherever required from the performance and emission standpoint. This paper presents a methodology for applying the burn rate law for common rail direct injection diesel engines adopted with split injection by using Wiebe’s correlation. The analysis reveals that while the empirical constant ‘m’ (shape factor) for both pilot and main injections is independent of engine load and seems to be affected by engine speed only, the constant ‘a’ (efficiency parameter) seems to be influenced by the engine speed, load and injection conditions. A correlation for these empirical constants with the respective parameters of dependence can be formulated which can be used to analyze the effect of change in engine operating conditions on combustion characteristics without conducting engine experiments.

scholarly journals Combustion Thermodynamics of Ethanol, n-Heptane, and n-Butanol in a Rapid Compression Machine with a Dual Direct Injection (DDI) Supply System

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2729
Author(s):  
Ireneusz Pielecha ◽  
Sławomir Wierzbicki ◽  
Maciej Sidorowicz ◽  
Dariusz Pietras
Keyword(s):  
Heat Release ◽  
Combustion Chamber ◽  
Internal Combustion Engines ◽  
Direct Injection ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Injection System ◽  
Rapid Compression Machine ◽  
Process Indicators ◽  
Rapid Compression

The development of internal combustion engines involves various new solutions, one of which is the use of dual-fuel systems. The diversity of technological solutions being developed determines the efficiency of such systems, as well as the possibility of reducing the emission of carbon dioxide and exhaust components into the atmosphere. An innovative double direct injection system was used as a method for forming a mixture in the combustion chamber. The tests were carried out with the use of gasoline, ethanol, n-heptane, and n-butanol during combustion in a model test engine—the rapid compression machine (RCM). The analyzed combustion process indicators included the cylinder pressure, pressure increase rate, heat release rate, and heat release value. Optical tests of the combustion process made it possible to analyze the flame development in the observed area of the combustion chamber. The conducted research and analyses resulted in the observation that it is possible to control the excess air ratio in the direct vicinity of the spark plug just before ignition. Such possibilities occur as a result of the properties of the injected fuels, which include different amounts of air required for their stoichiometric combustion. The studies of the combustion process have shown that the combustible mixtures consisting of gasoline with another fuel are characterized by greater combustion efficiency than the mixtures composed of only a single fuel type, and that the influence of the type of fuel used is significant for the combustion process and its indicator values.

scholarly journals Influence of the diesel pilot injector configuration on ethanol combustion and performance of a heavy-duty direct injection engine

2021 ◽  
pp. 146808742110012
Author(s):  
Nicola Giramondi ◽  
Anders Jäger ◽  
Daniel Norling ◽  
Anders Christiansen Erlandsson
Keyword(s):  
Direct Injection ◽  
Engine Performance ◽  
High Load ◽  
Operating Conditions ◽  
Injection System ◽  
Injection Timing ◽  
Diesel Combustion ◽  
Heavy Duty ◽  
Pure Ethanol ◽  
Ethanol Combustion

Thanks to its properties and production pathways, ethanol represents a valuable alternative to fossil fuels, with potential benefits in terms of CO2, NOx, and soot emission reduction. The resistance to autoignition of ethanol necessitates an ignition trigger in compression-ignition engines for heavy-duty applications, which in the current study is a diesel pilot injection. The simultaneous direct injection of pure ethanol as main fuel and diesel as pilot fuel through separate injectors is experimentally investigated in a heavy-duty single cylinder engine at a low and a high load point. The influence of the nozzle hole number and size of the diesel pilot injector on ethanol combustion and engine performance is evaluated based on an injection timing sweep using three diesel injector configurations. The tested configurations have the same geometric total nozzle area for one, two and four diesel sprays. The relative amount of ethanol injected is swept between 78 – 89% and 91 – 98% on an energy basis at low and high load, respectively. The results show that mixing-controlled combustion of ethanol is achieved with all tested diesel injector configurations and that the maximum combustion efficiency and variability levels are in line with conventional diesel combustion. The one-spray diesel injector is the most robust trigger for ethanol ignition, as it allows to limit combustion variability and to achieve higher combustion efficiencies compared to the other diesel injector configurations. However, the two- and four-spray diesel injectors lead to higher indicated efficiency levels. The observed difference in the ethanol ignition dynamics is evaluated and compared to conventional diesel combustion. The study broadens the knowledge on ethanol mixing-controlled combustion in heavy-duty engines at various operating conditions, providing the insight necessary for the optimization of the ethanol-diesel dual-injection system.

Experimental and Analytical Characterization of Alternative Aviation Fuel Sprays Under Realistic Operating Conditions

2018 ◽  
Author(s):  
Andrew Corber ◽  
Nader Rizk ◽  
Wajid Ali Chishty
Keyword(s):  
Experimental Data ◽  
Alternative Fuels ◽  
Laser Sheet ◽  
National Research Council ◽  
Diagnostic System ◽  
Operating Conditions ◽  
Aviation Fuel ◽  
Injection System ◽  
Test Time

The National Jet Fuel Combustion Program (NJFCP) is an initiative, currently being led by the Office of Environment & Energy at the FAA, to streamline the ASTM jet fuels certification process for alternative aviation fuels. In order to accomplish this objective, the program has identified specific applied research tasks in several areas. The National Research Council of Canada (NRC) is contributing to the NJFCP in the areas of sprays and atomization and high altitude engine performance. This paper describes work pertaining to atomization tests using a reference injection system. The work involves characterization of the injection nozzle, comparison of sprays and atomization quality of various conventional and alternative fuels, as well as use of the experimental data to validate spray correlations. The paper also briefly explores the application viability of a new spray diagnostic system that has potential to reduce test time in characterizing sprays. Measurements were made from ambient up to 10 bar pressures in NRC’s High Pressure Spray Facility using optical diagnostics including laser diffraction, phase Doppler anemometry (PDA), LIF/Mie Imaging and laser sheet imaging to assess differences in the atomization characteristics of the test fuels. A total of nine test fluids including six NJFCP fuels and three calibration fluids were used. The experimental data was then used to validate semi-empirical models, developed through years of experience by engine OEMs and modified under NJFCP, for predicting droplet size and distribution. The work offers effective tools for developing advanced fuel injectors, and generating data that can be used to significantly enhance multi-dimensional combustor simulation capabilities.

Parametric Study of the Scavenging Process in Marine Two-Stroke Diesel Engines

2015 ◽  
Author(s):  
Fredrik Herland Andersen ◽  
Stefan Mayer
Keyword(s):  
Diesel Engines ◽  
Vortex Breakdown ◽  
Initial Conditions ◽  
Combustion Process ◽  
Operating Conditions ◽  
Exhaust Valve ◽  
Delivery Ratio ◽  
Exhaust Gas ◽  
Scale Production ◽  
Cfd Model

Large commercial ships such as container vessels and bulk carriers are propelled by low-speed, uniflow scavenged two-stroke diesel engines. The integral in-cylinder process in this type of engine is the scavenging process, where the burned gas from the combustion process is evacuated through the exhaust valve and replaced with fresh air for the subsequent compression stroke. The scavenging air enters the cylinder via inlet ports which are uncovered by the piston at bottom dead center (BDC). The exhaust gas is then displaced by the fresh air. The scavenging ports are angled to introduce a swirling component to the flow. The in-cylinder swirl is beneficial for air-fuel mixture, cooling of the cylinder liner and minimizing dead zones where pockets of exhaust gas are trapped. However, a known characteristic of swirling flows is an adverse pressure gradient in the center of the flow, which might lead to a local deficit in axial velocity and the formation of central recirculation zones, known as vortex breakdown. This paper will present a CFD analysis of the scavenging process in a MAN B&W two-stroke diesel engine. The study include a parameter sweep where the operating conditions such as air amount, port timing and scavenging pressure are varied. The CFD model comprise the full geometry from scavenge receiver to exhaust receiver. Asymmetric inlet and outlet conditions is included as well as the dynamics of a moving piston and valve. Time resolved boundary conditions corresponding to measurements from an operating, full scale production, engine as well as realistic initial conditions are used in the simulations. The CFD model provides a detailed description of the in-cylinder flow from exhaust valve opening (EVO) to exhaust valve closing (EVC). The study reveals a close coupling between the volume flow (delivery ratio) and the in-cylinder bulk purity of air which appears to be independent of operating conditions, rpm, scavenge air pressure, BMEP etc. The bulk purity of air in the cylinder shows good agreement with a simple theoretical perfect displacement model.

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