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A model was developed for a lean NOx trap (LNT) used in a diesel application. The accuracy of the LNT model was validated using data from flow reactor experiments and vehicle testing. It is demonstrated that the model agrees with the experiments reasonably well on both reactor and vehicle test data. The LNT model was then applied to simulate the NOx emissions at the trap outlet over the FTP cycle, and quantitatively evaluate the effect of inlet CO concentration, inlet H2 concentration, inlet gas temperature, and trap size on NOx conversion performance of the LNT. The LNT model was also integrated with an exhaust pipe model to investigate the impact of engine exhaust configuration on NOx conversion. The integration of the LNT model with the engine exhaust model is valuable in the assessment of engine exhaust configuration and NOx trap performance.

Emissions standards are becoming increasingly harder to reach without the use of exhaust aftertreatment systems such as Selective Catalytic Reduction and particulate filters. In order to make efficient use of these systems it is important to have accurate models of engine-out emissions. Such models are also useful for optimizing and controlling next-generation engines without aftertreatment using for example exhaust gas recirculation (EGR). Engines are getting more advanced using systems such as common rail fuel injection, variable geometry turbochargers (VGT) and EGR. With these new technologies and active control of the injection timing, more sophisticated models than simple stationary emission maps must be used to get adequate results. This paper is focused on the calculation of engine-out NOx and engine parameters such as cylinder pressure, temperature and gas flows.

Given the quantity and severity of head injuries to pedestrians in vehicle-to-pedestrian collisions, human pedestrian finite element models and pedestrian dummies must possess a biofidelic head/neck response to accurately reproduce head-strike kinematics and kinetics. Full-scale pedestrian impact experiments were performed on post-mortem human surrogates (PMHS) using a mid-sized sport utility vehicle and a small sedan. Kinematics of the head and torso were obtained with a six-degree-of-freedom (6DOF) cube, which contained three orthogonally mounted linear accelerometers and three angular rate sensors. The goal of the current study was to present a methodology for analyzing the data obtained from the sensors on each cube, and to use the kinematics data to calculate spatial trajectories, as well as linear velocities and angular accelerations of the head and T1 vertebra.

Previous studies utilizing the Polar-II pedestrian dummy have suggested the need for a more biofidelic pelvis design in order to improve the overall dummy response kinematics. The current Polar-II dummy pelvis is a rigid steel structure. A preliminary version of a modified deformable pelvis equipped with sensors for measuring internal deflection and load has been designed. The goal of this study was to assess the biofidelity of these two pelves in full-scale tests with the Polar-II dummy that mimic lateral pelvic impact tests on PMHS (post-mortem human subjects) reported in the literature. The force - time, deflection - time, and force - deflection histories were compared to new PMHS response corridors determined using a normalization technique. In all tests with both pelves, the initial response (i.e., the first 3 ms to 5 ms following initial dummy - impactor contact) appeared to be totally determined by the mechanical behavior of the flesh.

A finite element (FE) model that can predict impact response and injuries to a human pelvis and lower limb was developed in PAM-CRASH™ by accurately representing human anatomical structures. In our previous study, three-dimensional (3D) geometry of the thigh, leg and knee joint was developed based on MRI scans from a human volunteer. 3D geometry of a bony pelvis created in this study was based on CT scans from a Post Mortem Human Subject (PMHS). The model was validated using published quasi-static and dynamic test results with human pelves and lower limbs. The thigh and leg models were validated against recently published dynamic 3-point bending test results with off-center loading. The validation results showed that this model can reproduce force-deflection and moment-deflection responses of a human thigh and leg in various loading conditions along with average force and moment at fracture.

The effects of several variables on pitting fatigue life of carburized steels were analyzed using a geared roller test machine (GRTM). The material variables that were primarily used to influence retained austenite include aim surface carbon concentration (0.8 % and 0.95 %), alloy (SAE 4320 and a modified SAE 4122), and cold treatment (performed on one material condition per alloy). Testing variables included contact stress in addition to a variation in lambda ratio (oil film thickness/surface roughness), arising from variation in roughness among the machined surfaces. Test results are presented, and differences in performance are considered in terms of material and testing variables. A primary observation from these results is an improvement in contact fatigue resistance apparently arising from cold-treatment and the associated reduction of retained austenite at the surface.

Meeting increasingly stringent targets for vehicle performance, economy and emissions requires a deep understanding of the overall IC engine system behavior and the ability to optimize it considering all control and noise factors and their variations. The tradeoffs in exhaust gas temperature, exhaust valve temperature, engine performance, economy and emissions demand a combination of capable CAE analytical tools and a methodology capable of leading the design to a reliable and robust solution. This paper presents a newly developed methodology that uses a Ford in-house quasi-dimensional combustion model called GESIM (General Engine Simulation Program) and a 3D conjugate heat transfer (CHT) model to predict crank angle resolved exhaust gas temperatures and cycle average valve temperatures in a 6-Sigma context, which considers a wide range of engine factors and their variations, to determine a feasible robust design solution.

A general purpose engine friction model, based on lubrication theory was developed and is presented in this paper. The model takes into account the friction components of the complete ring pack, piston skirt, main/connecting rod bearings and valve train mechanism. Using the developed model, it is possible to predict the complete engine friction (either in crank angle resolution or in engine cycle resolution (Friction Mean Effective Pressure, FMEP), the trajectory of moving components (e.g. piston secondary motion, journal movements in bearings, piston rings motion towards cylinder liner), the pressure field developed by the lubricant. The model was used with data from a four-stroke medium speed marine diesel engine installed in the National Technical University of Athens/Laboratory of Marine Engineering test-bed. The effect of engine speed and engine load on predicted frictional losses was examined and compared with results obtained from other semi-empirical FMEP models.

Rising gas prices at the fuel station, stronger emission requirements at the tail pipe have required more and more fine-tuning of the internal motor components. To support the customers in this difficult task, MAHLE has developed a Power Cell Unit (PCU). The newly introduced lightweight PCU with the MAHLE patented ECOFORM® piston, an optimized pin and high strength material connecting rod offers the customer a complete system that is focused on less reciprocating masses, lower friction and better NVH. The PCU as a unit has been developed for each and every component as well as the interaction of all these components to additionally benefit the customer with less program management, organization, logistic and reduction of development time because all parts are made in-house by MAHLE. An example using a conventional PCU in production versus a weight optimized version is provided for comparative purposes.

Newly designed gears are subject to higher loads that demand a steel that is capable of greater pitting resistance. The application of shot peening to gears has been increasing to improve tooth root strength, but pitting resistance had not been necessarily high. This study examines the effect of alloying additions mainly on tempering resistance and the formation of a non-martensitic layer. The developed high Si-Mo type steel shows excellent pitting resistance, even in shot peened gears, as compared to that of conventional steels due to high tempering resistance and the thin, uniform non-martensitic layer. This new steel is of practical use in some multi-speed automatic transmission gears.

This paper introduces a novel design of an internal combustion engine heat transfer model within a comprehensive simulation environment. The modelling is based on a lumped mass parameters approach. The paper discusses an approach for a heat transfer model, implemented in MATLAB/SIMULINK, the coupling process and the physical interface. The methodology of implementing this model in a comprehensive simulation environment is presented. The calculation of the combustion process and the inner circuits for the water and oil loops, considered as boundary conditions for the Heat Transfer Model are performed using the 1D engine cycle simulation program BOOST i.e. the 1D cooling simulation program KULI. This results in a scalable and modular structure of the model, which in turn permits a flexible design of different engine types. In order to carry out a comprehensive thermal calculation, a coupled simulation with these three different models is performed.

Two soot-containing turbulent non-premixed flames burning gaseous acetylene in atmospheric-pressure air were investigated by conducting non-intrusive optical experiments at various flame locations. The differences in burner exit Reynolds numbers of these flames were large enough to examine the influence of flow dynamics on soot formation and evolution processes in heavily-sooting flames. By accounting for the fractal nature of aggregated primary particles (spherules), the proper interpretation of the laser scattering and extinction measurements yielded all the soot parameters of principal interest. With the separation of spherule and aggregate sizes, the axial zones of the prevailing turbulent soot mechanisms were accurately identified. With the high propensity of acetylene fuel to soot, relatively fast particle nucleation process led to high concentrations immediately above the burner exit.

Changing and more stringent emissions norms and fuel economy requirements often call for modifications in the fuel injection system of a Diesel engine. There exists a strong interaction between the injection system hydraulics and the dynamics of mechanical components within the unit injector and the camshaft-driven mechanical system used to pressurize it. Hence, accurate predictive analysis of design issues or evaluation of design changes requires highly coupled and integrated hydro-mechanical simulations, combining analysis of fuel injection hydraulics and the dynamics of all mechanical parts, including the cam-drive system. This paper presents an application of such an integrated model to the study and alleviation of an observed increase in mechanical vibration and related noise levels associated with a proposed design change in unit injectors and valve-train of a 6-cylinder truck diesel engine.

Study and modeling of transient operation is an important scientific objective. This is due to the fact that the majority of daily vehicle driving conditions involve transient operation, with non-linear situations experienced during engine transients. Thus, proper interconnection is needed between engine, governor, fuel pump, turbocharger and load. This paper surveys the publications available in the open literature concerning diesel engine simulations under transient operating conditions. Only those models that include both full engine thermodynamic calculations and dynamic powertrain modeling are taken into account, excluding those that focus on control design and optimization. Most of the attention is concentrated to the simulations that follow the filling and emptying modeling approach. A historical overview is given covering, in more detail, research groups with continuous and consistent study of transient operation.

Sodium borohydride hydrogen storage systems offer great promise in meeting the challenges of hydrogen storage for automotive applications. The physical processes inside a NaBH4 packed-bed reactor are complicated, involving multi-component, multi-phase, multi-mode heat and mass transfer. All of these processes are closely coupled with chemical reaction kinetics. To design and optimize the reactor, a detailed reactor model is needed. This study addressed this problem using a one-dimensional homogeneous model. The diffusion coefficient inside the catalyst and the water vapor mass transfer coefficient were obtained by fitting experimental data at a moderate flow rate and were used to predict reactor behaviors at other flow rates. The predicted temperature, conversion and relative humidity profiles match experimental data well although the pressure drops are underpredicted.

In this paper a fast DPF screening procedure is proposed using small-scale filter samples of different technologies in a well-controlled environment but under realistic engine exhaust conditions. The DPF samples are evaluated in a specially built Multi-Reactor Assembly (MRA) with respect to their flow resistance, filtration efficiency, soot loading behavior, soot oxidation behavior, as well as their ash induced ageing behavior.

Autoignition of a homogeneous mixture is very sensitive to operating conditions, therefore fast control is necessary for reliable operation. There exists several means to control the combustion phasing of an Homogeneous Charge Compression Ignition (HCCI) engine, but most of the presented controlled HCCI result has been performed with single-input single-output controllers. In order to fully operate an HCCI engine several output variables need to be controlled simultaneously, for example, load, combustion phasing, cylinder pressure and emissions. As these output variables have an effect on each other, the controller should be of a structure which includes the cross-couplings between the output variables. A Model Predictive Control (MPC) controller is proposed as a solution to the problem of load-torque control with simultaneous minimization of the fuel consumption and emissions, while satisfying the constraints on cylinder pressure.

Widespread implementation of homogeneous charge compression ignition (HCCI) engines is presently hindered by stability, control, and load range issues. Although the operable HCCI speed/load range is expanding, it is likely that the initial HCCI engines will rely on conventional combustion for part of the operating cycle. In the present study, we have investigated the role of fuel properties and chemistry on the operation of a spark-assisted gasoline HCCI engine. The engine employed is a single cylinder, 500 cc, port fuel injected research engine, operating near lambda = 1.0 and equipped with hydraulic variable valve actuation. HCCI is initiated by early exhaust valve closing to retain exhaust in the cylinder, thereby increasing the cylinder gas temperature. This is also referred to as a ‘negative overlap’ strategy.

Early direct injection with HCCI like properties is characterized by the presence of an ignition dwell - the interval between end of fuel injection and start of combustion, during which fuel-air mixing occurs. Previous work by Jhavar and Rutland (2005) has focused on investigating different methods to affect fuel-air mixing during the ignition dwell. That study helped to evaluate the relative influence of various mixing control strategies to achieve ignition control. In this study, we attempt to look into the mixture preparation process in more detail. Therefore, turbulence is studied using Large Eddy Simulation (LES) models in place of Reynolds Averaged Navier Stokes (RANS) models. While LES is computationally more expensive than RANS, it depicts the flow structure more accurately. Therefore, it can be applied to engines in order to gain a better representation of local mixing as well as accurately simulate unsteady flow behavior in engines.

The tightening of diesel emissions legislation throughout the EU and US is leading to the development of emission control devices to enable diesel engines to meet the standards. One system which has shown great promise in controlling PM emissions is Diesel Particulate Filter (DPF). Even DPF has showed good filtering efficiency, it has also lots of challenge for serial applications. One of the challenges is regeneration of filtered PM at urban driving condition. Since the temperatures are much lower than those of PM oxidation by itself. Active systems are proposed to ensure the regeneration along variable driving conditions. In this study, Photocatalyst-Plasma and Honeycomb (PPH) is proposed as an active and continuous regeneration system of DPF on the road. The results show a good feasibility of PPH system for PM regeneration with lower power consumption without an increasing pressure on the DPF.