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Viewing 1 to 30 of 184415
2004-03-08
Technical Paper
2004-01-1639
Cheolwan Kim, Chin-Yuan Perng, Dengfu Zhang
In this paper we describe the application of a CFD methodology to characterize the orifice flows over a wide range of flow conditions with various geometrical features commonly found in hydraulic control systems. There are three objectives in carrying out this study. First, apply CFD analyses to provide physical insight into the orifice flow physics and clarify the use of relevant engineering parameters critical to hydraulic control applications. Second, quantify orifice discharge coefficient with respect to orifice diameter ratio, cross-sectional shape, plate thickness, orifice entrance and exit geometries. Third, support physical test and establish building block elements for hydraulic system modeling. The results obtained from CFD calculations agree very well with available data published in professional handbooks and fluid mechanics related textbooks, especially in the high Reynolds number flow regime.
2003-10-27
Technical Paper
2003-01-3150
Essam M. EL-Hannouny, Sreenath Gupta, Christopher F. Powell, Seong-Kyun Cheong, Jinyuan Liu, Jin Wang, Raj R. Sekar
The process of spray atomization has typically been understood in terms of the Rayleigh-Taylor instability theory. However, this mechanism has failed to fully explain much of the measured data. For this reason a number of new atomization mechanisms have been proposed. The present study intends to gain an understanding of the spray dynamics and breakup processes in the near-nozzle region of heavy-duty diesel injector sprays. As this region is optically dense, synchrotron x-rays were used to gain new insights. This spray study was performed using a prototype common-rail injection system, by injecting a blend of diesel fuel and cerium-containing organometalic compound into a chamber filled with nitrogen at 1 atm. The x-rays were able to probe the dense region of the spray as close as 0.2 mm from the nozzle. These x-ray images showed two interesting features. The first was a breakup of the high density region about 22 μs After the Start Of Injection (ASOI).
2003-10-27
Technical Paper
2003-01-3102
Paul W. Loustalan, Martin H. Davy, Paul A. Williams
This paper presents the results of an experimental study into the liquid sheet break-up mechanisms of high-pressure swirl atomizers of the type commonly used in direct-injection spark-ignition (DISI) engines. Sheet disintegration was investigated at two fuel pressures: 5 and 10 MPa, and three ambient back pressures: 50, 100 (atmospheric) and 200 kPa for a pre-production DISI injector. Microscopic images of the near-nozzle spray region were obtained with a high-speed rotating drum camera and copper vapour laser. For the range of conditions considered, the results show the initial break-up to occur in ‘perforated-sheet’ mode. A novel ‘void fraction’ analysis technique was applied to multiple images from the steady-state period of a single injection event in order to characterise and quantify details of the sheet break-up process. The sheet break-up lengths obtained by the authors were compared with the break-up lengths predicted by three commonly employed models from the literature.
2003-10-27
Technical Paper
2003-01-3101
Alex C. Alkidas, Sherif H. El Tahry
A methodology was developed, based on engine-simulation analysis and experiments, to evaluate quantitatively the contributions of the various factors on the fuel-economy advantage of direct-injection, spark-ignition (DISI) engines over corresponding port-fuel injection (PFI) engines. The fuel-economy comparison was based on a set of seven, steady-state test points, which simulate a 2400-kg vehicle powered by a 5.3-L V8 engine over the Federal Test Procedure (city cycle). The results show that the DISI engine has a 15% fuel-economy advantage over the corresponding PFI engine operating without EGR. The biggest positive contributor to this gain is the reduced pumping losses, which account for a 10% gain, followed by: favorable mixture properties due to lean/dilute operation with about a 7.5% gain, lower heat losses with a 2% gain, and higher compression ratio with a 3% gain.
2003-10-27
Technical Paper
2003-01-3104
Holger Lienemann, John S. Shrimpton
The present investigation is centered around two motored research gasoline direct-injection engines, equipped with a pressure-swirl atomizer closely spaced with the centrally located spark plug. At first a Laser Doppler Velocimetry system was employed to characterize the in-cylinder airflow in one of the engines. A comparison was made to velocity profiles in a port-fuel injected engine of similar design characteristics, which revealed a different decay mechanism of the large-scale flow structure and associated higher turbulence levels in the pentroof of the cylinder. Second, images of the hollow cone fuel spray generated by the direct injector were recorded for three different injection timings in order to discuss the temporal and spatial development of the liquid phase in the engine cylinder in terms of its interaction with the gas motion.
2003-10-27
Technical Paper
2003-01-3103
Yangbing Zeng, Sebastian Strauss
This paper presents a numerical study on air-fuel mixing in a two-stroke direct injection spark ignition engine under homogeneous operation. The simulated engine is loop scavenged and uses an outwardly opening swirl injector. A generic mesh-snapping algorithm is developed to enable the moving piston to snap through transfer ports with complicated geometry. A spray model based on Linear Instability Sheet Atomization is used to describe the primary breakup of fuel sprays, and the initial rotational velocity of the conical sheet is determined from a CFD simulation of the nozzle internal flow. A wall film model accounting for the effect of contacting area is also developed to avoid the severe grid-dependence of the original film model in KIVA. Comparisons between simulations and experiments were made for sprays in quiescent ambient conditions, and a good agreement of the spray characteristics was obtained. The simulations were performed for four different injection timings.
2003-10-27
Technical Paper
2003-01-3096
Rahman M. Montajir, Terunao Kawai, Hisakazu Suzuki, Hajime Ishii, Yuichi Goto, Matsuo Odaka
Fuel formulation for premixed charge compression ignition (PCCI) combustion has been attempted based on the mixture formation and auto-ignition behavior of normal paraffin fuels. Different pure and mixed fuels with different blending ratios are tested. The mixture formation behavior is investigated photographically in a constant volume combustion chamber (CVCC) at elevated temperature and pressure. Auto-ignition behavior is tested in a Fuel Ignition Analyzer under different test conditions. It is found that the evaporation rate of pure n-paraffin fuel increases and the ignition delay becomes longer with decreases in the chain length. In the range of test condition used in this study, the flash-boiling phenomenon affects the fuel evaporation rate and ignition delay to some extent. Based on the experimental results a mixture of a very light mixture promoting component (MPC) and a moderately dense igniting component (IC) at a ratio of 3:1 is found to be optimum for PCCI combustion.
2003-10-27
Technical Paper
2003-01-3095
Rui Liu, David S.-K. Ting, M. David Checkel
Ammonia is a potential alternative fuel that was indeed put into use in Belgium in World War II due to the extreme shortage of diesel. It has a high heating value per unit volume (1.16 × 107 kJ/m3) and its combustion products can be as or more environment-friendly compared to conventional hydrocarbon fuels. This study examined the combustion characteristics of premixed ammonia-air mixtures at atmospheric and elevated conditions which are encountered in SI engine operation. The laminar burning velocity, flame temperature and species distribution were determined using the Lindstedt mechanism in CHEMKIN. A freely propagating flame was assumed to facilitate the investigation. The predicted laminar burning velocity and the flammability limits were compared with experimental values.
2003-10-27
Technical Paper
2003-01-3099
James Hilditch, Zhiyu Han, Top Chea
The sources of unburned hydrocarbon (UHC) emissions in direct injection stratified charge engines are presented. Whereas crevices in the combustion chamber are the primary sources of UHC emissions in homogeneous charge engines, lean quenching and liquid film layers dominate UHC emissions in stratified charge operation. Emissions data from a single cylinder engine, operating in stratified charge mode at a low speed / light load condition is summarized. This operating point is interesting in that liquid film formation, as evidenced by smoke emissions, is minimal, thus highlighting the lean quenching process. The effects of operating parameters on UHC emissions are demonstrated via sweeps of spark advance, injection timing, manifold pressure, and swirl level. The effects of EGR dilution are also discussed. Spark advance is shown to be the most significant factor in UHC emissions. A semi-empirical model for UHC emissions is presented based on the analysis of existing engine data.
2003-10-27
Technical Paper
2003-01-3094
T. Shudo, W. K. Cheng, T. Kuninaga, T. Hasegawa
Hydrogen can be readily used in spark-ignition engines as a clean alternative to fossil fuels. However, a larger burning velocity and a shorter quenching distance for hydrogen as compared with hydrocarbons bring a larger cooling loss from burning gas to the combustion-chamber wall. Because of the large cooling loss, the thermal efficiency of a hydrogen-fueled engine is sometimes lower than that of a conventionally fueled engine. Therefore, the reduction of the cooling loss is very important for improving the thermal efficiency in hydrogen-combustion engines. On the other hand, the direct-injection stratified charge can suppress knocking in spark-ignition engines at near stoichiometric overall mixture conditions. Because this is attributed to a leaner end gas, the stratification can lead to a lowered temperature of burning gas around the wall and a reduced cooling loss.
2003-10-27
Technical Paper
2003-01-3126
John J. Batteh, Eric W. Curtis
The physics of the mixture preparation process plays a critical role in transient engine control, a key enabler for satisfying increasingly stringent emissions requirements. This paper presents a fully transient, coupled model in Modelica for the liquid fuel behavior and thermodynamic engine cycle including thermal effects for a port fuel injection engine. Details of both the liquid fuel transport and cycle simulation models are provided. The integrated model is used to examine the effects of variable cam timing on the transient fuel behavior including comparisons between simulation results and experimental data under a variety of engine operating conditions.
2003-10-27
Technical Paper
2003-01-3127
Paul Bowles, John Batteh
This paper describes a transient, thermodynamic, crank angle-based engine model in Modelica that can be used to simulate a range of advanced engine technologies. A single cylinder model is initially presented and described, along with its validation against steady-state dynamometer test data. Issues related to this single cylinder validation are discussed, including the appropriate conservation of hot residual gases under very early intake valve opening (IVO) conditions. From there, the extension from a single cylinder to a multi-cylinder V8 engine model is explained and simulation results are presented for a transient cylinder-deactivation scenario on a V8 engine.
2003-10-27
Technical Paper
2003-01-3122
A. Gogan, B. Sundén, L. Montorsi, S. S. Ahmedand, F. Mauss
For the simultaneous evaluation of the influence on engine knock of both chemical conditions and global operating parameters, a combined tool was developed. Thus, a two-zone kinetic model for SI engine combustion calculation (Ignition) was implemented into an engine cycle simulation commercial code. The combined model predictions are compared with experimental data from a single-cylinder test engine. This shows that the model can accurately predict the knock onset and in-cylinder pressure and temperature for different lambda conditions, with and without EGR. The influence of nitric oxide amount from residual gas in relation with knock is further investigated. The created numerical tool represents a useful support for experimental measurements, reducing the number of tests required to assess the proper engine control strategies.
2003-10-27
Technical Paper
2003-01-3123
Christel Elmqvist, Fredrik Lindström, Hans-Erik Ångström, Börje Grandin, Gautam Kalghatgi
The objective of this paper is to present a simulation model for controlling combustion phasing in order to avoid knock in turbocharged SI engines. An empirically based knock model was integrated in a one-dimensional simulation tool. The empirical knock model was optimized and validated against engine tests for a variety of speeds and λ. This model can be used to optimize control strategies as well as design of new engine concepts. The model is able to predict knock onset with an accuracy of a few crank angle degrees. The phasing of the combustion provides information about optimal engine operating conditions.
2003-10-27
Technical Paper
2003-01-3124
Fredrik Westin, Hans-Erik Ångström
In this paper results from two different 1D engine simulation software (GT-Power and Virtual Engines) are compared to measured data. A list of simulation output properties is suggested, the order of which should be followed when calibrating the model, to make the simulation work as accurate and simple as possible. The model buildup is described in detail and the focus is on the turbocharger. For submodels aside from the turbocharger, the simplest possible options were selected, such as Wiebe model for the combustion, imposed measured wall temperatures for intercooler and manifolds. For the turbocharger model the paper describes in detail the adjustments and hands-on work that were necessary to achieve results close to measurements. Both transient simulations of the engine as well as simulations of thermocouple output are covered.
2003-10-27
Technical Paper
2003-01-3120
Ducai Wang, Derrick D. Parker
The effects of crank-pin surface circumferential waviness, also known as journal lobing or chatter in engineering terms, on bearing performance have been investigated by carrying out an elastohydrodynamic lubrication analysis. The big-end bearing in a 2.0 liter diesel engine has been used for the study. The operating condition is that of maximum torque with engine running at 1800rpm. The crank pin has been assumed to have 2, 3, 5, 9, 15, 30 and 50 lobes. Sufficiently fine meshes have been used to model the lobe profiles. Solutions cover a large range of lobe amplitude and lobe orientation angles. The results show that journal lobing has adverse effects on the bearing's lubrication performance because it severely reduces the oil film thickness and significantly increase the oil film pressure. The combination of large lobe numbers and big lobe amplitudes is particularly detrimental.
2003-10-27
Technical Paper
2003-01-3111
Jesper Schramm
Abstract The IEA Advanced Motor Fuels Agreement has initiated this project concerning the application of biodegradable lubricants to diesel and gasoline type vehicles. Emission measurements on a chassis dynamometer were carried out. The purpose of these measurements was to compare the emissions of CO, CO2, NOx, THC, PM, lubricant-SOF and PAH from one diesel and one gasoline type vehicle using biodegradable lubricants and conventional lubricants. This paper describes the results of the experiments with the diesel type vehicle only. Lubricant consumption and fuel consumption are other important parameters that have been evaluated during the experiments. Both vehicle types were operated on conventional crude oil based fuels and alternative fuels. The diesel vehicle was operated on conventional diesel fuel from a Danish fuel station, low sulfur diesel from Sweden and biodiesel, which was bought at a fuel station in Germany.
2003-10-27
Technical Paper
2003-01-3283
Keith C. Corkwell, Mitchell M. Jackson, Daniel T. Daly
Recently, research and testing of oxygenated diesel fuels has increased, particularly in the area of exhaust emissions. Included among the oxygenated diesel fuels are blends of diesel fuel with ethanol, or E diesel fuels. Exhaust emissions testing of E diesel fuel has been conducted by a variety of test laboratories under various conditions of engine type and operating conditions. This work reviews the existing public data from previous exhaust emissions testing on E diesel fuel and includes new testing performed in engines of varied design. Emissions data compares E diesel fuel with normal diesel fuel under conditions of different engine speeds, different engine loads and different engine designs. Variations in performance under these various conditions are observed and discussed with some potential explanations suggested.
2003-10-19
Technical Paper
2003-01-3304
Yuji Goto, Atsushi Yasuda, Satoshi Ishida
The brake master cylinder for a heavy weight vehicle which can offer the optimal braking effect and brake feel has been developed. This brake master cylinder has mechanical type work-bore switching mechanism without electric control system between the conventional master cylinder and the conventional vacuum type booster, it combines enough braking effect during a vacuum failure condition with the secure brake feel during the normal condition. This master cylinder operates in large bore during the normal operation and enables secure brake feel. It operates in smaller bore during a vacuum failure condition and enhances braking effect. The work-bore switching unit has a sealing pressure chamber of a large diameter, the work-bore switching action is carried out by open/close operation of the bore switching valve which has built-in this unit.
2003-10-19
Technical Paper
2003-01-3317
Shinichi Ozeki
Phenolic resins have been widely used as a binder for friction materials, but due to the demand for increased performance requirements, it has made the friction suppliers look at modifications to standard phenolic resins. Various modified phenolic resins have been developed and their performance levels and capabilities have been improved. Concern for both the environment and the work place must be considered during the development of any new product. New phenolic resins for friction should therefore be improved to address environmental issues as well as performance issues. New processes have been developed to reduce free phenol and increase yield, at the same time reducing the waste phenol by-product.. Technology for “dust free” resins provides a cleaner working environment at reduced production costs. Furthermore, a combination of these environmental technologies and modifications solves both performance requirements and environmental concerns in the friction industry.
2003-10-19
Technical Paper
2003-01-3316
Gary McIntyre, Rudiger Holinski
In the past, many different remedies have been tried to eliminate the sources of annoying brake noise, e.g., replacing brake hardware, adding shims, resurfacing the rotors, etc. The composition of the brake linings was seldom considered, since asbestos-filled materials possess many characteristics important to low noise operation. With the disappearance of asbestos from brake linings, many other materials were evaluated in order to maintain performance while keeping brake noise to a minimum. Fillers like calcium silicate, glass fiber, mica, etc. offer some similar performance characteristics to asbestos. Friction modifiers, such as metal oxides, metal sulfides, rubber scrap, etc are also used to maintain a more constant coefficient of friction during braking. Among the metal sulfides, molybdenum disulfide (MoS2) is often used since it possesses very good dry lubricating properties.
2003-10-19
Technical Paper
2003-01-3331
Richard Roberts, Martin Schautt, Henry Hartmann, Bernd Gombert
The eBrake® is a novel self-reinforcing electromechanical wedge brake[1]. Self reinforcement reduces the actuation forces, resulting in a more efficient and smaller brake, but demands more precise control than a conventional braking system. As a result, mathematical modelling and control law development plays a significant role in the development process. This paper describes the mathematical model of the brake and its validation against the prototype hardware. It is shown that there is a good correspondence between theory and practice, demonstrating both the validity of the model and its potential as a tool in future developments. Both the model and test results illustrate that the potential advantages of this design are realisable in practice.
2003-10-27
Technical Paper
2003-01-3246
Kalyana Chakravarthy, C. S. Daw, K. E. Lenox
Abstract We study the NOx storage process in lean NOx traps using bench-flow experiments and simulated diesel exhaust. Given that formulation alone is an inadequate indicator of performance (due to the effects of manufacturing processes) a minimal set of experiments is always needed to compare the performance of LNTs. We define simple performance measures based on such a set of experiments that can be used to compare lean phase operations of various LNTs under various conditions concisely. Though the noble metal sites are essential for storage, the benefits of increasing noble metal loading start to wane beyond a certain limit. Our experiments suggest a possibility that a lean NOx reduction reaction may be occuring in LNTs. If this reaction is confirmed further in future experiments, its products need to be identified. The sorbent shifts the equilibrium between NO and NO2 towards NO.
2003-10-27
Technical Paper
2003-01-3259
Stephen Shih, Edwin Itano, Jun Xin, Michio Kawamoto, Yoshio Maeda
Improvement of engine cycle thermal efficiency is an effective way to increase engine torque and to reduce fuel consumption simultaneously. However, the extent of the improvement is limited by engine knock, which is more evident at low engine speeds when combustion flame propagation is relatively slow. To prevent engine damage due to knock, the spark ignition timing of a gasoline engine is usually controlled by a knock sensor. Therefore, an engine's ignition timing cannot be set freely to achieve best engine performance and fuel economy. Whether ignition timings for a multi-cylinder engine are the same or can be set differently for each cylinder, it is not desirable for each cylinder has big deviation from the median with respect to knock tendency. It is apparent that effective measures to improve engine knock toughness should address both uniformity of all cylinders of a multi-cylinder engine and improvement of median knock toughness.
2003-10-27
Technical Paper
2003-01-3260
Liguang Li, Zhimin Liu, Huiping Wang, Baoqing Deng, Zhensuo Wang, Zongcheng Xiao, Yan Su, Bin Jiang
This paper presents the development of an electronic control LPG gas injection system and its application in a small SI engine. The tests results show that the developed LPG gas injection system can meet the needs for the goal of high engine power output and low exhaust emissions based on the engine bench tests. With the LPG electronic gas injection system, the air-fuel ratio can be optimized based on the requirements and CO and NOx emission levels are decreased significantly compared with the LPG mechanical mixer fuel supply system, based on the same HC emission levels. With the new gas phase LPG electronic control injection system, the HC emission level is controlled below the 300 ppm under most engine conditions and under 200 ppm when the engine speed is over 3000 r/min. The NOx emission level is under 2600 ppm in the whole range of engine operation conditions and is decreased by 2000 ppm compared with the LPG mechanical mixer system.
2003-10-27
Technical Paper
2003-01-3271
Rodney L. Borup, Michael A. Inbody, José I. Tafoya, William J. Vigil, Troy A. Semelsberger
Fuel cells have high efficiency for conversion of fuel to electricity. However, most types of fuel cells do not have high power density and efficiency operating directly from existing hydrocarbon fuels, thus require fuel reforming. Fuels are likely to be different for differing fuel cell applications, and debates exist about future fuels for fuel cell transportation applications. Potential on-board vehicle applications for fuel cells include both prime mobility power and auxiliary power production. This work examines fuel reforming for PEM fuel cells for prime mobility for transportation applications. Major gasoline and diesel fuel constituents, such as aliphatic compounds, napthanes, and aromatics have been compared for their effect on the fuel processing performance, and fuel processor catalyst requirements. Hydrogen production from the catalytic oxidation and steam reforming of liquid hydrocarbon fuels is compared with homogeneous oxidation and catalytic steam reforming.
2003-10-27
Technical Paper
2003-01-3267
Jingshun Fu, Nobuo Kurihara
Fuel economy can be improved by adopting the method of lean burning and reducing idle speed. And to achieve it, it is required to improve the performance of idle speed control. The dead time in the process of intake air control is one of the reasons, which cause the worse response and poor stability of idle speed control. The problem of the dead time compensation for intake air control is investigated in this paper. The Smith predictor and various linear compensators are discussed in it. By using a proper compensator, it is possible to improve the performance of the system's disturbance rejection. A new compensation method is presented in this paper, which is adopting a Smith predictor combining with disturbance compensator M1(s) and M2(s), to improve the idle speed control system's response to the disturbance at the front or rear part of the dead time.
2003-10-27
Technical Paper
2003-01-3272
John P. Kopasz, Laura E. Miller, Daniel V. Applegate
Different blends of gasoline range hydrocarbons were investigated to determine the effect of aromatic, naphthenic, and paraffinic content on performance in an autothermal reformer. In addition, we investigated the effects of detergent, antioxidant, and oxygenate additives. These tests indicate that composition effects are minimal at temperatures of 800°C and above, but at lower temperatures or at high gas hourly space velocities (GHSV approaching 100,000 h-1) composition can have a large effect on catalyst performance. Fuels high in aromatic and naphthenic components were more difficult to reform. In addition, additives, such as detergents and oxygenates were shown to decrease reformer performance at lower temperatures.
2003-11-10
Technical Paper
2003-01-3380
Codrin-Gruie Cantemir, Chris Hubert, Giorgio Rizzoni, Gabriel Ursescu, Chris Yakes, Kaoru Yasuda
This paper presents the design and development of a high-power, high-speed “road train” (with both on- and off-road applications). The system looks to optimize both high-speed operation and low-speed, close-quarters driving with the introduction of autonomous power modules. Each trailer in the road train has it own electric traction system. When driving on open roads or in open areas, each traction system receives electric energy from the high-powered tractor. However, the individual traction systems allow for distributed tractive effort, improving upon the classic road train. Further, each module has its own independent steering system, allowing for practical implementation of longer trains. Use of longer trains in open areas allows for reduced operational costs, and increased efficiency. When mobility becomes a primary concern or zero emissions operation is needed, small power supplies can allow independent trailer operation.
2003-11-10
Technical Paper
2003-01-3369
Chan-Chiao Lin, Huei Peng, Jessy W. Grizzle, Jason Liu, Matt Busdiecker
The power management control system development and vehicle test results for a medium-duty hybrid electric truck are reported in this paper. The design procedure adopted is a model-based approach, and is based on the dynamic programming technique. A vehicle model is first developed, and the optimal control actions to maximize fuel economy are then obtained by the dynamic programming method. A near-optimal control strategy is subsequently extracted and implemented using a rapid-prototyping control development system, which provides a convenient environment to adjust the control algorithms and accommodate various I/O configurations. Dynamometer-testing results confirm that the proposed algorithm helps the prototype hybrid truck to achieve a 45% fuel economy improvement on the benchmark (non-hybrid) vehicle. It also compares favorably to a conventional rule-based control method, which only achieves a 31% fuel economy improvement on the same hybrid vehicle.
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