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Effects of fuel cell material properties on water management were numerically investigated using Volume of Fluid (VOF) method in the FLUENT. The results show that the channel surface wettability is an important design variable for both serpentine and interdigitated flow channel configurations. In a serpentine air flow channel, hydrophilic surfaces could benefit the reactant transport to reaction sites by facilitating water transport along channel edges or on channel surfaces; however, the hydrophilic surfaces would also introduce significantly pressure drop as a penalty. For interdigitated air flow channel design, it is observable that liquid water exists only in the outlet channel; it is also observable that water distribution inside GDL is uneven due to the pressure distribution caused by interdigitated structure. An in-situ water measurement method, neutron imaging technique, was used to investigate the water behavior in a PEM fuel cell.

The current study focused on the effects B20 fuel (20% soybean-based biodiesel) and SCR entrance shapes on a light-duty, high-speed, 2.8L common-rail 4-cylinder diesel engine, at different exhaust temperatures. The results indicate that B20 has less deNOX efficiency at low temperature than ULSD, and that N₂O emission need to be characterized as well as NH₃ slip. If a mixer and enough mixing length are used, longer divergence section does not improve the deNOX efficiency significantly under the speed ranges tested.

The use of biodiesel and its blends with ultra low sulfur diesel (ULSD) is gaining significant importance due to its ability to burn in conventional diesel engines with minor modifications. However the chemical and physical properties of biodiesel are different compared to the conventional ULSD. These differences directly impact the injection, spray formation, auto ignition and combustion processes which in turn affect the engine-out emissions. To understand the effect of fueling with B-20, tests were conducted on a single cylinder 0.42L direct injection research diesel engine. The engine is equipped with a common rail injection system, variable EGR and swirl control systems and was operated at a constant engine speed of 1500 rpm and 3 bar IMEP to simulated turbocharged conditions. Injection timing and duration were adjusted with B-20 at different locations of peak premixed combustions (LPPC) and two different swirl ratios to achieve 3 bar IMEP.

The effect of biodiesel on the Particulate emissions is gaining significant attention particularly with the drive for the use of alternative fuels. The particulate matter (PM), especially having a diameter less than 50 nm called the Nanoparticles or Nucleation mode particles (NMPs), has been raising concerns about its effect on human health. To better understand the effect of biodiesel and its blends on particulate emissions, steady state tests were conducted on a small-bore single-cylinder high-speed direct-injection research diesel engine. The engine was fueled with Ultra-Low Sulfur Diesel (ULSD or B-00), a blend of 20% soy-derived biodiesel and 80% ULSD on volumetric basis (B-20), B-40, B-60, B-80 and 100% soy-derived biodiesel (B-100), equipped with a common rail injection system, EGR and swirl control systems at a load of 5 bar IMEP and constant engine speed of 1500 rpm.

As early as the 1950's, Gurdjian and colleagues (Gurdjian et al., 1955) observed that brain injuries could occur by direct pressure loading without any global head accelerations. This pressure-induced injury mechanism was "forgotten" for some time and is being rekindled due to the many mild traumatic brain injuries attributed to blast overpressure. The aim of the current study was to develop a finite element (FE) model to predict the biomechanical response of rat brain under a shock tube environment. The rat head model, including more than 530,000 hexahedral elements with a typical element size of 100 to 300 microns was developed based on a previous rat brain model for simulating a blunt controlled cortical impact. An FE model, which represents gas flow in a 0.305-m diameter shock tube, was formulated to provide input (incident) blast overpressures to the rat model. It used an Eulerian approach and the predicted pressures were verified with experimental data.

Dynamic data, forces, moments and displacements are widely used parameters in a simulation environment for design and testing. These results may be obtained from field tests, laboratory measurements, and numerical simulations. The correctness of the simulation results depends strongly on the models and numerical solution techniques. This paper presents a preliminary examination of the differences between results obtained from the computer code DADS (Dynamic Analysis and Design System) [1] and the field data for the response of a military tank. The differences are analyzed by standard statistical methods in the frequency domain. The statistical tests show that DADS results differ from the measured field data and that the errors are not white noise. Moreover, the principal frequencies of the differences are identified.

JP-8 is an aviation turbine engine fuel recently introduced for use in military ground vehicle applications and generators which are mostly powered by diesel engines. Many of these engines are designed and developed for commercial use and need to be adapted for military applications. This requires more understanding of the auto- ignition and combustion characteristics of JP-8 under different engine operating conditions. This paper presents the results of a comparative analysis of an engine operation using JP-8 and ultra low sulfur diesel fuel (ULSD). Experiments were conducted on 0.42 liter single cylinder, high speed direct injection (HSDI) diesel engine equipped with a common rail injection system. The results indicate that the distillation properties of fuel have an effect on its vaporization rate. JP-8 evaporated faster and had shorter ignition delay as compared to ULSD. The fuel economy with JP-8 was better than ULSD.

An experimental investigation was conducted on a small-bore, high-speed diesel engine to study the effect of different operating parameters on combustion and engine-out emissions in the conventional and low temperature regimes. For the conventional diesel combustion, the spray behavior is analyzed and a differentiation is made between the conditions in the small-bore and the larger bore quiescent chamber engines. The effects of the injection pressure, exhaust gas recirculation (EGR), injection timing and swirl ratio (SR) on combustion and engine-out emission are investigated. The trade-off between NOx and smoke, measured in Bosch smoke unit, (BSU), is investigated with a special attention to the low temperature combustion regime, (LTC). The results showed that the LTC regime could be reached at fairly high EGR rates under all the injection pressures investigated in this work. The margin for the variation in EGR was limited just before the misfiring EGR.

Advanced injection systems play a major role in reducing engine out emission in modern diesel engines. One interesting technology is the common rail injection system which is becoming more vital in controlling emission due to its flexibility in injection pressure, timing and number of injection events. Many studies have showed the advantages of using such injection parameters to meet the strict emission and improve engine performance. A glow plug/ ion current sensor was used to measure ionization produced during the combustion process. The ion current signal contains many valuable information including combustion phasing, duration and combustion resonance. In prior publications, it was demonstrated the capability of the ion current to control the combustion phasing and the ability to detect combustion resonance. Therefore, the experimental testing was conducted under controlled combustion phasing using the feedback from the ion current sensor.

Requirements for reduced fuel consumption with simultaneous reductions in regulated emissions require more efficient operation of Spark Ignited (SI) engines. An advanced valvetrain coupled with Gasoline Direct injection (GDi) provide an opportunity to simultaneously reduce fuel consumption and emissions. Work on a flex fuel GDi engine has identified significant potential to reduce throttling by using Early Intake Valve Closing (EIVC) and Late Intake Valve Closing (LIVC) strategies to control knock and load. High loads were problematic when operating on gasoline for particulate emissions, and low loads were not able to fully minimize throttling due to poor charge motion for the EIVC strategy. The use of valve deactivation was successful at reducing high load particulate emissions without a significant airflow penalty below 3000 RPM. Valve deactivation did increase the knocking tendency for knock limited fuels, due to increased heat transfer that increased charge temperature.

It is well know that the internal flow field and nozzle geometry affected the spray behavior, but without high-speed microscopic visualization, it is difficult to characterize the spray structure in details. Single-hole diesel injectors have been used in fundamental spray research, while most direct-injection engines use multi-hole nozzle to tailor to the combustion chamber geometry. Recent engine trends also use smaller orifice and higher injection pressure. This paper discussed the quasi-steady near-nozzle diesel spray structures of an axisymmetric single-hole nozzle and a symmetric two-hole nozzle configuration, with a nominal nozzle size of 130 μm, and an attempt to correlate the observed structure to the internal flow structure using computational fluid dynamic (CFD) simulation. The test conditions include variation of injection pressure from 30 to 100 MPa, using both diesel and biodiesel fuels, under atmospheric condition.

Because of their robustness and cost performance, multi-hole gasoline injectors are being adopted as the direct injection (DI) fuel injector of choice as vehicle manufacturers look for ways to reduce fuel consumption without sacrificing power and emission performance. To realize the full benefits of direct injection, the resulting spray needs to be well targeted, atomized, and appropriately mixed with charge air for the desirable fuel vapor concentration distributions in the combustion chamber. Ethanol and ethanol-gasoline blends synergistically improve the turbo-charged DI gasoline performance, especially in down-sized, down-sped and variable-valve-train engine architecture. This paper presents the spray imaging results from two multi-hole DI gasoline injectors with different design, fueled with pure ethanol (E100) or gasoline (E0), under homogeneous and stratified-charge conditions that represent typical engine operating points.

Multi-hole DI injectors are being adopted in the advanced downsized DISI ICE powertrain in the automotive industry worldwide because of their robustness and cost-performance. Although their injector design and spray resembles those of DI diesel injectors, there are many basic but distinct differences due to different injection pressure and fuel properties, the sac design, lower L/D aspect ratios in the nozzle hole, closer spray-to-spray angle and hense interactions. This paper used Phase-Contrast X ray techniques to visualize the spray near a 3-hole DI gasoline research model injector exit and compared to the visible light visualization and the internal flow predictions using with multi-dimensional multi-phase CFD simulations. The results show that strong interactions of the vortex strings, cavitation, and turbulence in and near the nozzles make the multi-phase turbulent flow very complicated and dominate the near nozzle breakup mechanisms quite unlike those of diesel injections.

Complete validation of any finite element (FE) model of the human brain is very difficult due to the lack of adequate experimental data. However, more animal brain injury data, especially rat data, obtained under well-defined mechanical loading conditions, are available to advance the understanding of the mechanisms of traumatic brain injury. Unfortunately, internal response of the brain in these experimental studies could not be measured. The aim of this study was to develop a detailed FE model of the rat brain for the prediction of intracranial responses due to different impact scenarios. Model results were used to elucidate possible brain injury mechanisms. An FE model, consisting of more than 250,000 hexahedral elements with a typical element size of 100 to 300 microns, was developed to represent the brain of a rat. The model was first validated locally against peak brain deformation data obtained from nine unique dynamic cortical deformation (vacuum) tests.

Rattling in the inevitable clearances between engaging teeth of mechanical power transmission components, such as gears, gear couplings and clutches, etc., is becoming a more and more important issue, especially for automotive applications. An extensive research effort in this area is mostly dedicated to modeling of complex nonlinear processes that develop after the tooth separation occurs, or to experimental studies of these processes. The available abatement techniques for the rattling noise are expensive while not providing desirable noise reduction results. The paper presents a criterial condition for opening of clearances derived for a simplified model and clearly showing importance of various design parameters on possibility of commencement of the rattling process. Also, a novel rattling noise abatement technique is described, based on incorporating simple means for prolongation of the impact interactions between the co-impacting engaging teeth.

Port fuel injection system in gasoline engines is receiving an increasing attention for its potential advantages in meeting the constrains of simultaneous reduction in fuel consumption and exhaust emission, and maintaining a good engine performance. The structure of port injector spray dominates the mixture preparation process and strongly affect the subsequent engine combustion characteristics over a wide range of operating conditions in port-injection gasoline engines. In this paper, an experimental and analytical study is made to characterize the breakup mechanism and atomization process of the non-air-assisted port injector sprays in gasoline engines. The liquid sprays resulted from various types of current and development-type automotive fuel injectors were visualized using planar laser-induced fluorescence imaging technique. A comparison was made on the spray structure of the single hole and multi-hole injectors.

The flow structure inside the catalytic converter of gasoline engines is very important for consideration of the catalyst light-off condition, converter durability and conversion efficiency. However, the available experimental data under actual engine exhaust conditions are quite limited due to its complicated configuration, critical operating conditions and difficult optical access. Therefore, an experimental study was performed, using laser Doppler velocimetry technique, to measure the velocity distributions inside two production dual-monolith catalytic converters fitted on a firing gasoline engine over several engine operating conditions. This paper reports the normal velocity characteristics measured in a plane 1 mm away from the front surface of first monolith. A small fraction of titanium (IV) isopropoxide was dissolved in gasoline for generating titanium dioxide seeding particles during the engine combustion.

This paper summarizes a systematic approach to control of nonlinear automotive systems exposed to fast transients. This approach is based on a combined application of hardware characterization, which inverts nonlinearities, and conventional Proportional-plus-Integral-plus-Derivative (PID) control. The approach renders the closed-loop system dynamics more transparent and simplifies the controller design and calibration for applications in automotive industry. The authors have found this approach effective in presenting and teaching PID controller design and calibration guidelines to automotive engineering audience, who at times may not have formal training in controls but need to understand the development and calibration process of simple controllers.

Conventional gear designs are characterized by the meshing teeth which have to accommodate bending loads with a high dynamic load content, together with high contact stresses under a reciprocal sliding. Accordingly, special materials with sophisticated heat treatments, and high fabrication accuracy are required for heavy-duty gears, such as being used in off-road vehicle transmissions The paper describes a novel concept for designing power transmission gears, which eliminates physical sliding between meshing profiles and separates bending and contact loading of the teeth. Geometrical sliding is accommodated by internal shear deformation in specially designed rubber-metal laminates, thus allowing materials with high bulk strength but poor contact properties (aluminum, titanium, fiber-reinforced composites, etc.) to be used for heavy-duty gears.

Many approaches have been taken to determine the burning velocity in internal combustion engines. Experimentally, the burning velocity has been determined in optically accessible gasoline engines by tracking the propagation of the flame front from the spark plug to the end of the combustion chamber. These experiments are costly as they require special imaging techniques and major modifications in the engine structure. Another approach to determine the burning velocity is from 3D CFD simulation models. These models require basic information about the mechanisms of combustion which are not available for distillate fuels in addition to many assumptions that have to be made to determine the burning velocity. Such models take long periods of computational time for execution and have to be calibrated and validated through experimentation.