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A three-dimensional multi-zone combustion model is developed for the description of the combustion mechanism inside the engine cylinder of direct injection diesel engines. Various multi-zone models have been proposed in the past for the prediction of DI diesel engine performance and emissions. These models offer an alternative tool if one wants to avoid the use of other more complicated and sophisticated flow models that require high computational times. Most of them have the disadvantage that they focus mainly on emissions, failing to predict at the same time engine performance adequately. In almost all multi-zone models the resulting fuel jet after injection, which is divided into zones, is assumed to be symmetrical around its axis. In the present work a different approach is followed. The fuel jet is divided into zones in the three dimensions overcoming the need for the previous symmetry assumption.

Laboratory Simulation Testing is widely accepted as an effective tool for validation of automotive designs. In a simulation test, response data are measured whilst a vehicle is in service or tested at a proving ground. These responses are reproduced in the laboratory by mounting the vehicle or a subassembly of the vehicle in a test rig and applying force and displacements by servo hydraulic actuators. The data required as an input to the servo hydraulics, the drive files, are determined by an iterative procedure which overcomes the non linearity in the test specimen and the test rig system. Under certain circumstances, the iteration does not converge, converges too slowly or converges and then diverges. This paper uses mathematical and computer models in a study of the reasons why systems fail to convergence and makes recommendations about the management of the simulation test.

In conjunction with throttle-free load control on a 4-valve, single-cylinder spark-ignition engine, the influencing variables of charge cycle, mixture formation and combustion process are presented both as computer calculations and on the basis of test results. The influences of the position of the maximum of the inlet valve stroke, the position of the inlet close, the shape of the valve stroke and the load motion in relation to the maximum power and minimum fuel consumption are investigated in full load by computer calculations and in partial load by engine tests.

Camless actuation offers programmable flexibility in controlling engine valve events. However, a full range of engine benefits will only be available, if the actuation system can control lift profile characteristics within a particular lift event. Control of the peak value of valve lift is a first step in controlling the profile. The paper presents an adaptive feedback control of valve lift for a springless electrohydraulic valvetrain. The adaptive control maintains peak value of lift in presence of variations in engine speed, hydraulic fluid temperature and manufacturing variability of valve assemblies. The control design includes a reduced-order model of the system dynamics. Experimental results show dynamic behavior under various operating and environmental conditions and demonstrate advantages of adaptive control over the non-adaptive type.

A comprehensive structural analysis simulation model is used for describing the thermal condition of a four-stroke, air-cooled, DI diesel engine under steady and transient operation. Two- and three- dimensional finite element analyses are implemented for the representation of the complex geometry metal components (piston, liner, cylinder head), in a way that the temperature and heat flux variations are calculated during any transient event. A detailed thermodynamic simulation model of engine operation is utilized for the determination of boundary conditions on the combustion chamber sides of each component. During an engine transient, processing of experimental cylinder pressure diagrams on a cycle to cycle basis resulted in the estimation of heat resease rate and boundary conditions (gas temperature, heat transfer coefficient) variation from the initial to the final engine thermodynamic state. Consequently, the power and specific fuel consumption curves can be accurately determined.

In this study, a series of tests have been carried out to evaluate the effects of the injection rate and timing on bsfc, NOx, and PM emissions in a heavy-duty diesel engine with TICS FIE system. Injection line pressure, cylinder pressure, NOx and smoke were measured with various injection times and injection rates. The injection rate was altered at a fixed injection timing, which could be realized either by changing the TICS setting time or by using different cam profiles. The injection time was varied by using TICS timing control function at a given setting time. A parametric study of the injection rate in in-line pump system was tried to correlate injection rate variations with combustion characteristics and emission. Two parameters, the injection pressure rising rate and the initially injected fuel quantity were introduced to characterize fuel injection.

The paper describes a procedure for optimizing the conventional diesel fuel injection system by employing an approximation method of mathematical programming. The shape of the cam profile is represented by a Bézier curve and some of the coordinates of the control points are adopted as design variables. Other design variables concern the pump plunger prelift, the geometrical end of delivery and the length of high pressure tube. The objective function is build upon a target shape of the injection rate while the imposed constraints are related to the pump plunger acceleration, the local radius of the cam profile, the residual pressure, the vapour volume, the pressure squareness and to the design variables. The theory is illustrated with several numerical examples.

Numerical computations of combusting transient jets are performed under diesel-like conditions. Discussions of the structure of such jets are presented from global and detailed points of view. From a global point of view, we show that the computed flame heights agree with deductions from theory and that integrated soot mass and heat release rates are consistent with expected trends. We present results of several paramaters which characterise the details of the jet structure. These are fuel mass fractions, temperature, heat release rates, soot and NO. Some of these parameters are compared with the structure of a combusting diesel spray as deduced from measurements and reported in the literature. The heat release rate contours show that the region of chemical reactions is confined to a thin sheet as expected for a diffusion flame. The soot contour plots appear to agree qualitatively with the experimental observations.

Using a combination of imaging techniques, we have produced a database of the macroscopic properties of sprays produced by a common-rail injection system in a diesel simulation cell. The parameters of the data base include injection pressure (40, 80 and 150 MPa), gas-side temperature (387, 800 and 1100 K), gas density (12, 25 and 30 kg/m3), injector nozzle hole size (0.17 and 0.20 mm) and injection programs (with and without pilot injection). Single component fuels (heptane and dodecane) were used in order to simplify data interpretation and modeling. The spray characteristics which were measured include the initial “dispersion” angle of the nozzle, initial spray tip speeds, and spray tip penetration vs. time for both the liquid and vapor parts of the spray. The sites of initial self ignition and combustion propagation within the sprays were visualized, and a luminous delay was measured for several of the operating conditions.

In diesel engines, the existence of a very dense liquid region could dramatically increase the rate of soot formation due to the very low air penetration. This experimental study is a contribution to the understanding of the structure of such dense sprays. It is devoted to the influence of the injection pressure on the characteristics of a water stationary confined jet with emphasis on the fluctuating behavior of droplets and on air entrainment. A two component Phase Doppler Anemometer allows the measurement of velocities and diameter of the droplets. Velocity and fluctuation intensities are plotted in the axial and radial direction for many cross sections in the spray. First, we discuss the influence of the gas flow around the jet: when the jet does not discharge in an open atmosphere, the dense core length is twice as short as with an open atmosphere. The main result is the existence of two distinct regions in the spray which illustrate some aspects of air entrainment.

The KIVA-II code is probably the most advanced CFD code for simulating diesel engine fuel spray, but the atomization sub model remains imperfect. For this reason, several break-up models exist in published literature. The poor physical understanding of liquid break-up prevents it from being modeled faithfully. In our 1997 SAE Paper, a new approach was proposed, based on a jet fully atomized when leaving the nozzle. It avoids the break-up description by fixing some fictional initial conditions for droplet velocity, average diameter and size distribution. The originality lies in the choice of droplet injection velocity. The proposed initial velocity is roughly twice that normally used, i.e. the value found using the Bernoulli equation with a discharge coefficient of around 0.75.

Road simulators like shaker tables are commonly used in the automotive industry for component level dynamic testing. The purpose of a shaker table is to duplicate measured vehicle accelerations in a lab environment. However, there is no universal measure to describe the accuracy of iterated drive files for road simulators. This paper compares frequency domain methods based on discrete Fourier transforms with various time-frequency techniques to develop an accuracy measure which gives more information than metrics which are now common. Results are presented using road data from two typical vehicles and iterated drive files from a six axis shaker table.

Many problems are associated with applying standardized vehicle test methods, such as the Federal Test Procedure (FTP), to hybrid electric vehicles (HEVs). Since 1992, the Society of Automotive Engineers' (SAE's) HEV Test Procedure Task Force has been working on developing a standard procedure for HEV testing (Draft SAE J1711). Because the current draft requires considerable knowledge of the vehicle's response to the test cycles, still has unresolved problems, and is too lengthy, Argonne National Laboratory (ANL) uses portions of past J1711 drafts in combination with concepts developed through many HEV tests (over 50 to date) for its HEV competition testing. Successful vehicle characterization was achieved at the 1997 FutureCar Challenge competition by characterizing each vehicle's individual operational modes in such a way that the elements of the FTP and Federal Highway Test were satisfied.

Globalization in the automotive industry has resulted in a tremendous competitive advantage to those companies who can internally communicate ideas and information effectively and in a timely manner. This paper discusses one such effort related to objectively testing vehicles for steering and handling characteristics by implementing standard test procedures, data acquisition hardware and analysis methods. Ford Motor Company's Vehicle Dynamics Test Section has refined a number of test procedures to the point that, with proper training, all design and development engineers can quickly acquire, analyze and share test results. Four of these procedures and output are discussed in detail.

Spectrographic oil analysis technology has for the first time been introduced as a key engineering tool during the developmental phase for automotive engines and drive train systems. Placing an automated analytic instrument and reporting system at the test site provides timely data resulting in more efficient control of test programs. This produces significant savings in program time as well as component expense and laboratory resources.

This paper will describe the development of an in-vehicle data acquisition and analysis system. The problem facing the Vehicle Dynamics Test Section of Ford Motor Company was to replace an antiquated data recorder with a versatile in-vehicle data acquisition system capable of supporting vehicle dynamics testing and development. The following criteria for a system was developed: Quick and easy quick software and hardware setup Off-the-shelf hardware wherever possible User-friendly software Flexible Open-ended and modular design Rugged Cost effective Utilizing the above criteria a number of commercially available systems were evaluated and found to be lacking. Therefore it was decided that a system suitable for vehicle dynamics testing would have to be developed.

To be able to meet the demands of low emissions and low fuel consumption of modern combustion engines, new ways have to be found to control the engine efficiently. We measure the pressure in the combustion chamber and analyze this signal with a neural network in order to receive the point of 50% conversion of energy. Using this on-line computation of the point of 50% conversion of energy, we construct a linear feedback controller and a neural controller for the computation of the optimal ignition time. Several complex algorithms for the adaptation of the neural networks are employed and compared in this challenging application. All algorithms were implemented in an ECU and applied to the control of a Mercedes-Benz SI engine. Extensive engine tests were carried out and several results are shown in this article.

The spray characteristics of air-assisted fuel injection system and its effects on the combustion of port-injection type gasoline engine were investigated in this study. In order to supply assistant air for the atomization of injected fuel, several types of air-assisted injection adapter, which is not only easy to make and equip but also good for low-cost mass production, were designed and manufactured. The atomization characteristics of a multi-point type injector inserted into the adapter such as spray pattern, droplet distributions were evaluated using particle size analyzing system. Droplet sizes of fuel injection were decreased with assistant air supplied, and fine spray under 60mm of SMD was acquired on the conditions of air-assist pressure over 0.4bar. And the lean combustion performance of an MPI engine equipped with one of those adapters was tested on the dynamometer.

An infrared fiber optic instrumented spark plug probe has been used to measure the fuel concentration in the vicinity of the spark gap in a port injected gasoline fueled SI engine. The probe measured the fuel concentration spatially averaged over a distance of 6.3 mm near the spark plug for consecutive firing cycles. The crank angle resolution of the measurements was 2.5 degrees, for a temporal resolution of between 0.9 and 0.3 ms depending on the engine speed. Quantitative measurements of the fuel concentration in the pre-ignition regions of the engine cycle were obtained. Qualitative results are reported for unburned hydrocarbons in the post-combustion regions. The measurements were made in a single cylinder research engine over a range of speed, load, and stoichiometric conditions. Strong mixture inhomogeneities were measured during the intake stroke and the inhomogeneities decreased through the compression stroke.

Long term control of the AFR (Air/Fuel Ratio) of spark ignition engines is currently accomplished with a selvoscillating PI control loop. Because of the intake/exhaust time delay, the oscillation frequency and hence bandwidth of this loop is small. This paper describes a new approach to the design of this control loop using a novel observer system. In this way the bandwidth of this important loop is increased by a factor of 2 - 6 times, leading to more accurate overall AFR control. Moreover the observer approach is so robust and allows such feedback levels that it reduces significantly the accuracy required in the calibration of the base fuel control system with which it is be used. It can be used with either conventional- or advanced observer based- base fuel strategies.