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When designing and employing lubricants, film thickness modeling techniques must be used as part of an overall design approach to insure mating components, in relative motion, have proper lubricating films to separate surface asperities. Improper asperity separation will lead to increased friction and wear, and overall reduction in system reliability, serviceability and efficiency. Many of the tools used today to model tribofilms are rooted in empirical studies completed with hydrocarbon-based fluids as the lubricating medium. Generally, these modeling techniques have also been applied to non-hydrocarbon based lubricants, but this may not be an accurate method to model such fluids. As demands for improved lubricant performance continue to rise, so too does the need for improved tribofilms modeling techniques. This paper will discuss a modeling technique developed in which silicone-based polymer molecular structures are designed with tribological film performance in mind. The models consider molecular structures of various traditional and newly-developed silicone fluids, and relate that structure to rheological performance. Expected rheological performance is then used to model tribological film formation and characteristics. The output of these tribological film formation and characteristic models can then be fed back to the molecular structure module and iterated to achieve optimal molecular structure for the intended tribological performance. In addition, a graphical user interface has also been developed to aid in the data input to the modeling software.

Spark-ignition (SI) engines can derive substantial efficiency gains from operation at high dilution levels. Additionally, the use of exhaust gas recirculation (EGR) for charge dilution also maintains compatibility with three-way catalysts by allowing stoichiometric operation. However, running high dilution levels increases the occurrence of misfires and partial burns, which induce higher levels of cyclic-variability in engine operation. This variability has been shown to have both stochastic and deterministic components. Factors such as in-cylinder turbulence and mixing-variations can be classified as stochastic; while, charge composition is the major source of the deterministic component through its non-linear effect on ignition and flame propagation characteristics. The use of these deterministic components has been previously explored to construct next-cycle control approaches that would allow stable operation near the edge of stability. Building on that work, this paper aims to understand the effect of spark strategies, specifically the use of a second spark (restrike) after the main spark, on engine operation at high dilution levels that were achieved using both excess air (i.e. lean combustion) and EGR.

This paper assesses methane low pressure direct injection with stratified charge in a SI engine to highlight its potential and downsides. Experiments were carried out in a spark ignited single cylinder optical engine with stratified, homogeneous lean and stoichiometric operational mode, with focus on stratified mode. A dual coil ignition system was used in stratified mode in order to achieve sufficient combustion stability. The fuel injection pressure for the methane was 18 bar. Results show that stratified combustion with methane spark ignited direct injection is possible at 18 bar fuel pressure and that the indicated specific fuel consumption in stratified mode was 28% lower compared to the stoichiometric mode. Combustion and emission spectrums during the combustion process were captured with two high-speed video cameras. Combustion images, cylinder pressure data and heat release analysis showed that there are fairly high cycle-to-cycle variations in the combustion. Both blue pre-mixed flame and soot luminescence occurred in the combustion. The occurrence of soot luminescence was also supported by the emission spectrum. Soot formation sources were found to be localized randomly in the bulk flame but not on the piston nor in the vicinity of the spark plug. These findings illustrate the difficulty of achieving proper mixing between air and methane resulting in fairly high cycle-to-cycle variations in the combustion and fuel rich areas which create a source of soot.

Silicone fluids are known to have high Viscosity Indices (VI), and high Oxidation Onset Temperatures (OOT). Silicone VI and OOT characteristics make these fluids appealing for use as lubricants in high temperature applications, and where lubricant longevity is desired. Despite thermal and oxidative benefits, silicones lubricants have a reputation as being poor lubricants in metal-to-metal applications, and are typically only selected for use in plastic applications. Most industrial knowledge about silicone lubricants is based on characteristics of PolyDiMethyl Siloxanes (PDMS), in which case, lubricity limitations do exist. However, there are other silicone-based lubricating fluid technologies, that have been commercially available for decades, that far exceed known lubricity performance of PDMS, and in some ways, can rival traditional synthetic hydrocarbon. Phenyl-Methyl Silicones (PMS), Fluoro-Silicones (FS), and Alkyl-Methyl Silicones (AMS) can offer great performance at high temperatures due to the high VI and OOT for which silicones are known, and their molecular structures enable improved lubricity as compared to PDMS, giving these unique silicones combinatory benefits of thermal and oxidative stability and lubricity, even in metal-to-metal applications. This paper will discuss and compare different silicone-based fluids, as well as some comparison to polyalphaolefins, perfluoropolyethers, and other common synthetic lubricant technologies. Basic molecular structures will be reviewed, and comparative test data will be shared, including SRV (Schwingungs-Reibungs und Verschleisstest) data, 4-Ball wear scar data, Viscosity Index and Differential Scanning Calorimetry (DSC). Following data sharing, a few potential high temperature applications ideas will be presented.

Copyright © 2016 SAE International. As a potential material for lightweight vehicle, polymethyl methacrylate (PMMA) has proven to perform well in optical behavior and weather resistance. However, the application in automotive glazing has seldom been studied. This paper investigates the defrost performance of PMMA rear window using both numerical and experimental methods. The finite element analysis (FEA) results were found to be in good agreement with the experimental data. Based on the validated finite element model, we further optimized the defrost efficiency by changing the arrangement of heating lines. The results demonstrated the frost layer on the vision-related region of PMMA rear window can melt within 30 minutes, which meets the requirement of defrost efficiency.

Partially Premixed Combustion (PPC) is a promising combustion concept with high thermodynamic efficiency and low emission level, and also with minimal modification of standard engine hardware. To use PPC in a production oriented engine, the optimal intake charge conditions for PPC should be included in the analysis. The experiments in this paper investigated and confirmed that the optimal intake conditions of net indicated efficiency for PPC are EGR between 50% and 55% as possible and the lambda close to 1.4. Heat-transfer energy and exhaust gas waste-energy contribute to the majority of the energy loss in the engine. The low EGR region has high heat-transfer and low exhaust gas enthalpy-waste, while the high EGR region has low heat-transfer and high exhaust gas waste-enthalpy. The optimal EGR condition is around 50% where the smallest energy loss is found as a trade-off between heat transfer and exhaust-gas enthalpy-waste. Lambda close to 1.4 results from the trade-off of high gas-exchange efficiency with low lambda and high thermodynamic efficiency with high lambda. The optimal inlet charge condition was also applied to a multi-cylinder engine from low load to high load. The results indicate that the highest net indicated efficiency of the experimental engine was 49.7% at 13.5 bar IMEPn (Net Indicated Mean Effective Pressure), the highest brake efficiency was 44.2% observed at 17.2 bar IMEPn. (Less)

International audience; We present an experimental and modelling methodology developed at LGRE research laboratory to characterize soot oxidation in the presence of different atmospheres (NO2, NO2/O2), simulating passive regeneration which occur in a Diesel Particulate Filter (DPF). Based on this methodology which aims at deriving the kinetic parameters for soot combustion, the thermal reactivity of different soot has been studied and compared. Soot were produced from a prototype Liebherr engine and on an engine dynamometer at RandD Moteurs company, under two engine cycles and for two different fuels. Small soot masses (15-30mg) were deposited on the quartz frit of the reactor and submitted to a gas flow (NO2 or NO2/O2), under different temperatures. The mole fractions of NO2, NO, CO2 and CO at the reactor outflow were measured by infrared analyzers. The soot oxidation rate and the sample remaining mass were deduced from CO/CO2 emissions.In order to determine the intrinsic kinetic parameters for soot combustion, we improved a model already built at LGRE and consisting of a coupled system of five partial differential equations which describe the spatial or the temporal evolutions of the gas mole fractions (NO2, CO, CO2 and NO) and of the sample mass. The numerical resolution of this model involves an optimization procedure which determines the best kinetic constants of this model comparing the experimental and the computed (at the reactor outflow) mass loss rates and gas mole densities at different temperatures.

Ice crystals ingested by a jet engine at high altitude can partially melt and then accrete within the compressor, potentially causing performance loss, damage and/or flameout. Several studies of this ice crystal icing (ICI) phenomenon conducted in the RATFac (Research Altitude Test Facility) altitude chamber at the National Research Council of Canada (NRCC) have shown that liquid water is required for accretion. CFD-based tools for ICI must therefore be capable of predicting particle melting due to heat transfer from the air warmed by compression and possibly also due to impact with warm surfaces. This paper describes CFD simulations of particle melting and evaporation in the RATFac icing tunnel for the former mechanism, conducted using a Lagrangian particle tracking model combined with a stochastic random walk approach to simulate turbulent dispersion. Inter-phase coupling of heat and mass transfer is achieved with the particle source-in-cell method. Predictions are compared to turbulence measurements and measurements of total-water and liquid-water content (TWC, LWC) obtained with iso-kinetic and SEA multi-element probes respectively. They are also compared to measured changes in air temperature and humidity ratio resulting from particle evaporation and melting. Good agreement is obtained for these changes under (low pressure) conditions where they are large and interphase heat/mass coupling is very significant. Predicted LWC levels bracket the SEA measurements at low values but are much greater at higher LWC. These predictions suggest that the critical LWC/TWC range for ICI accretion may be higher than previously inferred from SEA measurements., SAE 2015 International Conference on Icing of Aircraft, Engines, and Structures, June 22-25 2015, Prague, Czech Republic

Selective catalytic reduction (SCR) has become the mainstream approach for removing heavy-duty (HD) diesel engine NOx emissions. Highly efficient SCR systems are a key enabling technology allowing engines to be calibrated for very high NOx output with a resultant gain in fuel consumption while still maintaining NOx emissions compliance. One key to the successful implementation of high efficiency SCR at elevated engine out NOx levels is the ability to introduce significantly more AdBlue into the exhaust flow while still ensuring complete ammonia production and avoiding the formation of deposits. This paper presents a body of experimental work conducted on an exhaust test bench using optical techniques including high-speed imaging and phase Doppler interferometry (PDI), applied under representative exhaust conditions to a HD diesel engine after-treatment system with optical access inside the mixer tube. Two different sprays were used to dose AdBlue onto the mixing device. A three-hole injector and a single-hole pressure-swirl injector were characterised in ambient and heated exhaust flow conditions. A metallic two-stage mixer and an uncoated cordierite ceramic substrate mixer were compared and demonstrated the ability of the substrate mixer to reduce deposit formation at higher dosing rates inside the mixer tube when used with the correct spray type. High-speed imaging revealed the ability of the substrate to absorb injected AdBlue spray at cooler exhaust temperatures. However, using the incorrect spray can lead to liquid saturation inside the substrate channels, which is detrimental due to the formation of deposits on the rear face of the substrate.

Instances have occurred where the outer surface of turbocharger fully floating journal bearing bushings have exhibited damage from oil debris resulting in constant tone noise and subsequent warranty claims. This paper studies the effect of oil debris in Turbocharger journal bearings on Subsynchronous NVH. A CFD model is built to study the behavior of oil debris particles with different sizes. It is found that the dominant centrifugal forces prevent larger particles from reaching the inner film while smaller particles travel more easily to the inner film. It is also found that the turbine side is more likely to become damaged from debris than the compressor side bearing due to higher temperatures. A tribology analysis shows that oil debris particles in the outer film will reduce the speed ratio, while oil debris particles in inner film will increase the speed ratio. The tribology analysis also predicts the effects of oil debris on bearing stiffness and damping. These stiffness and damping effects are incorporated into a rotordynamics simulation to predict the influence on Subsynchronous NVH. Shaft tip displacements and bearing forces are predicted as a relationship to oil debris particles collected in the inner or outer film. It is found that the peak dynamic reaction forces at the bearings can increase two fold as compared to undamaged bushings and clean oil films. The predicted frequency of these Subsynchronous forces matches well with measured data taken from vehicles exhibiting offending constant tone noises whose bearing bushings were found heavily damaged from oil debris.

This paper presents a numerical study of trace knocking combustion of ethanol/gasoline blends in a modern, single cylinder SI engine. Results are compared to experimental data from a prior, published work [1]. The engine is modeled using GT-Power and a two-zone combustion model containing detailed kinetic models. The two zone model uses a gasoline surrogate model [2] combined with a sub-model for nitric oxide (NO) [3] to simulate end-gas autoignition. Upstream, pre-vaporized fuel injection (UFI) and direct injection (DI) are modeled and compared to characterize ethanol's low autoignition reactivity and high charge cooling effects. Three ethanol/gasoline blends are studied: E0, E20, and E50. The modeled and experimental results demonstrate some systematic differences in the spark timing for trace knock across all three fuels, but the relative trends with engine load and ethanol content are consistent. Possible reasons causing the differences are discussed. Finally, the influence of NO on autoignition is investigated, yielding results that are consistent with prior works. Overall, the same, two-zone kinetic model appears to capture both the UFI and DI autoignition similarly well. These results also provide further evidence suggesting that inclusion of a NO sub-model is necessary for mechanistically accurate modeling of autoignition and knock in general.

The progressing exhaust gas legislation for on- and off-road vehicles includes gradually the nanoparticle count limits. The invisible nanoparticles from different emission sources penetrate like a gas into the living organisms and may cause several health hazards. The present paper shows some results of a modern chain saw with & without oxidation catalyst, with Alkylate fuel and with different lube oils. The measurements focused specially on particulate emissions. Particulates were analysed by means of gravimetry (PM) and granulometry SMPS (PN). In this way the reduction potentials with application of the best materials (fuel, lube oil, ox-cat.) were indicated.

Mechanical components, such as parts of internal combustion engine, subject to cyclic loads can be submitted to quenching process in order to improve mechanical properties preventing fatigue failures in service. It is important that such components, due to quenching process, get a high hardness surface layer, increasing the resistance to fatigue, and a tenacious core, with a high capacity of absorbing impacts. In this paper, a multiphysics simulation method of quenching process using Finite Element Method is presented. The proposed simulation method include two stages: heating and cooling. In the first stage, the mechanical component, initially at ambient temperature, is heated by electromagnetic induction to a temperature above the steel austenitization. In the second one, the component is cooled by liquid immersion. The resulting microstructure is calculated using the Johnson–Mehl– Avrami–Kolmogorov model and Sheil’s additive rule for diffusional transformation, while austenite-martensite transformation is calculated by Koistinen-Marburguer equation. The proposed method takes into account the variation of the material thermal properties as a function of temperature and microstructure, while the material electromagnetic properties are a function of temperature and strength of the electromagnetic field (magnetic permeability). As a result, the distribution of microstructure and hardness profile after quenching is obtained for a typical carbon steel, SAE 1080, for a mechanical component application.

The objective of this paper is to simulate the air flow (cold run) inside a single cylinder research engine for different geometries of the piston crown and investigate the influence of them on the Tumble coefficient and Squish. The study was conducted through the software star-CD, with the module esice (Expert System – Internal Combustion Engine) and simulations of the air flow with the flat piston were carried out at the first time. Once the simulation methodology was created according to its correlation with the experimental results, the geometry of the piston crown is changed and other numerical simulations are performed. Thereby, with the comparison between the obtained results for different geometries, the air flow inside the combustion chamber can be characterized, and the effects of the geometry changing on the Tumble coefficient, Squish and other flow parameters verified.

Magneto-rheological (MR) fluid is a type of smart material which has ability to change its flow resistance on the application of magnetic field. This property of changing viscosity of the fluid due to application of magnetic field is utilized in the MR brake. MR brake typically consists of multiple rotating disks immersed in MR fluid and an enclosed electromagnet. The controllable yield stress produces shear friction on the rotating disks, generating the braking torque. Of late MR brakes have been explored for automotive applications. Literature review reveals that the torque output of MR brake is not sufficient for braking of mid-sized car. Hence, it is worthwhile to investigate its application for a two-wheeler where the braking torque requirement is low. This paper presents design and simulation of MR brake performance for its torque output. Design of MR brake involves deciding the configuration of MR brake in terms of number and sizing of disks, selection of MR fluid and design of magnetic circuit. The response of MR brake in terms of torque output with respect to influencing parameters like speed, current, number of disks, MR fluid properties and intensity of magnetic field can be observed with the help of simulation in order to save cost and time associated with experimental testing. MATLAB/SIMULINK software environment has been used for this simulation. Introduction of MR Fluid Magneto-rheological (MR) fluid is the material that responds to an applied magnetic field with a dramatic change in rheological behavior. MR fluid is in a free-flowing liquid state in the absence a magnetic field, but under a strong magnetic field its viscosity can be increased by more than two orders in a very short time (milliseconds) and it exhibits solid-like characteristics [1]. The magnetizable particles (mainly iron) are suspended in an appropriate carrier liquid. The carrier fluid serves as a dispersed medium and ensures the homogeneity of particles in the fluid. A variety of additives (stabilizers and surfactants) are used to prevent gravitational settling and promote stable particles suspension, enhance lubricity and change initial viscosity of the MR fluid [2]. Figure 1 Chain-Like Structure Formation in Controllable Fluids [3] In the presence of an applied magnetic field, the iron particles acquire a dipole moment aligned with the external field which causes particles to form linear chains aligned to the magnetic field, as shown in Figure

In this paper, a two-dimensional microstructure-based finite element modeling method is adopted to investigate the effects of material parameters of the constituent phases on the macroscopic tensile behavior of Q&P steel and then to do a computational materials design approach for its performance improvement. For this purpose, a model Q&P steel is first produced and various experiments are then performed to characterize the steel. Actual microstructure-based model is generated based on the information from EBSD, SEM and nano-indentation test, and the material properties for the constituent phases are determined based on the initial constituents’ properties from HEXRD test and the subsequent calibration of model prediction to tensile test results. Influence of various material parameters of the constituents on the macroscopic behaviors is then investigated by separately adjusting them by small amount. Based on the observation on the respective influence of constituents’ material parameters, a new set of material parameters are devised, which results in better performance in ductility. The results indicate that various material parameters may need to be concurrently adjusted in a cohesive way in order to improve the performance of Q&P steel. In summary, higher austenite stability, less strength difference between the phases, higher hardening exponents of themore » phases are generally beneficial for the performance improvement. The information from this study can be used to devise new Q&P heat-treating parameters to produce the Q&P steels with better performance.« less

In this paper, it is explained how composite structures, made of continuous fibers embedded in a polymer matrix, are designed and analyzed in the aerospace industry. The strategy is based on the building block approach, in which the knowledge on the composite material and structure is built step by step from the coupon level up to the final full scale structure. Damage is then discussed, as it can't be ignored when composites are concerned. The approach available in the SAMCEF finite element code is then described. It is based on the continuum mechanics approach, and allows studying the progressive failure of composites in the plies and at their interface (so considering delamination). The material models are described, and their use is illustrated at the coupon level. The identification procedure for this damage models is also discussed. It is therefore shown how this information of the material behavior can be used at the upper stages of the building block approach and so applied to larger scale structures. It is advocated here that this approach can be used for the automotive applications, leading to a transfer of technology from aerospace to automotive.

This paper presents a model system TEG-DORC that employs thermoelectric generator (TEG) as a topping cycle integrated with a dual-loop organic Rankine bottoming cycle (DORC) to recover exhaust heat of internal combustion engine (ICE). The thermodynamic performance of TEG-DORC system is analyzed based on the first and second law of thermodynamics when system net output power Wnet, thermal efficiency ηth, exergy efficiency ηe and volumetric expansion ratio are chosen as objective functions. The model has many parameters that affect combined system performance such as TEG scale, evaporation pressure of high temperature ORC loop (HT loop) Pevp,HT, condensation temperature of HT loop Tcond,HT. It is suggested that HT loop has a vital influence on system performance. The results show that TEG-DORC system can significantly improve system performance, and system net output power gets maximum (30.69kW) when Tcond,HT is 370K and Pevp,HT is 4MPa, accordingly, the absolute effective thermal efficiency increases by 5.2%. The maximum thermal efficiency and exergy efficiency are 26.39% and 53.08% respectively. And applying TEG modules can't promote DORC system performance as expected.

Computer software, which simulates the thermodynamic and gas dynamic of internal combustion engines, are used extensively during design and development process. This paper analyzes the 1D boundary multi-pipe junctions calculations using the Method of Characteristics (MOC). Sonic flows can be encountered in the exhaust manifolds of internal combustion engines (especially racing engines) and in the model a check if the flow is sonic or not have been made. Flows with more than one manifold have flow toward the junction, need an equivalent "Datum" manifold, with an airflow as the sum of all flows, an averaged area and stagnation enthalpy has been defined in order to calculate the pressure loss when crossing the junction. The pressure loss terms have been calculated as function of the flow-ratio of the gas flowing to the manifold to the total incoming flow and the pipe angle. Such terms take into account of the flow ratio referred to the "Datum" flow and the pipe angle term is the average of all the pressure losses of every duct with incoming flow. The main model used to calculate the wave actions in the manifolds is the Two Step Lax-Wenfroff scheme, second order in space and time with the TVD flux limiter, needed to smooth the instabilities typical of second order hyperbolic schemes. Two set of tests have been designed in order to show the advantages of the present formulation. The first is "Y" junction with an inlet duct. Increasing the inlet pressure, the flow increase up to reach the sonic flow. The second test is a Y junction with 2 inlet ducts with the third duct that goes to sonic flow. A racing engine has also been simulated comparing the results with those from a dynamometer, showing good accordance between model and measured data. Copyright © 2013 SAE International.

"Progress in hole drilling technique is opening new perspectives in diesel nozzle design. In such a scenario, research on unconventional hole shapes looks worthwhile, in order to evaluate their influence on fuel flow features within the nozzle. In the present paper, investigations have been based on modeling. Moving from a standard hole configuration towards oval shaped holes, 3D-CFD campaigns have been devoted to highlight the hole layout influence on diesel nozzle flow. The investigations have been focused both on the fuel flow pattern at hole inlet and on the flow features at hole exit section; in such a modeling process, transient data concerning spatial distribution of velocity, turbulent kinetic energy and cavitation behavior at hole exit have been computed, highlighting the perturbations induced by the unconventional hole shape on the fuel flow; once the flow behavior has been explored, results have been resumed indicating how flow pattern properties are reflected at hole exit, quantitatively"

Composite materials have gained the attention of the automotive industry to substantially reduce vehicle weight, reduce CO2 emissions and improve the fuel economy of next generation vehicles. Thermosetting matrix technology combined with glass or carbon fiber reinforcements are well suited for structural applications where mostly steel and aluminum are used today. However, the lack of fast production techniques and fast reacting matrix technologies have limited composites use to low volume production models. A new generation of epoxy resin systems has been developed that allows the rapid processing of structural composites for medium to high volume models. These advanced formulations maintain the excellent properties of traditional epoxy-based composites, yet the tested systems can process in a matter of minutes using modern manufacturing technologies such as the high pressure resin transfer molding (HP-RTM) process. The advanced formulations are unique in that they provide a long enough injection window for a robust impregnation of the reinforcing fibers while still enabling an extremely short cure cycle. The results from this development show that structural composite components can be produced economically and in high volume using today’s innovative resin and process technology. Introduction Automotive manufacturers, particularly the European premium carmakers, are working vigorously on reducing the weight of their fleets and have begun introducing composite materials on higher volume commercial models. Fiber reinforced plastics using either glass or carbon fibers as reinforcement and thermosetting epoxy resin matrices are an extremely powerful material combination for saving weight in structural applications. As equipment manufacturers have continued to make improvements to the range of composite processes such as prepreg, filament winding, compression and resin transfer molding, resin manufacturers have had to develop new resin systems to compliment these high volume / high speed processes. Requirements include shorter cure time, VOC-free and REACH-compliant systems that do not sacrifice the desirable characteristics of traditional epoxy resins. This paper focuses on the development of material technology for the resin transfer molding (RTM) manufacturing process which is among the leading technologies for making structural composite parts. The entire process, as illustrated in Figure 1, requires a short cycle time (< 5 minutes) to be viable for automotive mass production volumes. Today, the main bottlenecks are the manufacture of the preform (Steps 1-2), and the actual injection and cure of the part (Step 4).

The latest trend world-wide, is to restrict the use of fossil fuels and replace them partially or totally by renewable fuels. In the present study, Jatropha methyl ester (JME) blended with tyre pyrolysis oil (TPO) was tested in a single cylinder, 4 stroke, air cooled, direct injection (DI) engine, to evaluate the performance and emissions characteristics. Four JMETPO blends, namely, JMETPO5, JMETPO10, JMETPO15 and JMETPO20 were used as fuel in the engine. The performance and emission results were analysed and compared with those of diesel operation. The results of the investigation indicate that the engine can run with JMETPO blends without any engine modification. The brake thermal efficiency of the engine fueled with the blends decreased marginally compared to that of diesel. The CO, HC and smoke emissions were found to be lower for the JMETPO blends in comparison with diesel. The NO emission increased with the JMETPO blends. The results are presented in this paper.

Controlling ignition delay is the key to successfully enable partially premixed combustion in diesel engines. This paper presents experimental results of partially premixed combustion in an optically accessible engine, using primary reference fuels in combination with artificial exhaust gas recirculation. By changing the fuel composition and oxygen concentration, the ignition delay is changed. To determine the position of the flame front, high-speed visualization of OH-chemiluminescence is used, enabling a cycle resolved analysis of OH formation. A clear correlation is observed between ignition delay and flame location. The mixing of fuel and air during the ignition delay period defines the local equivalence ratio, which is estimated based on a spherical combustion volume for each spray. The corresponding emission measurements using fast-response analyzers of CO, HC and NOX confirm the decrease in local equivalence ratio as a function of ignition delay. Furthermore multiple injection strategies are investigated, applying pilot as well as post injections, in combination with a main injection at constant load. From these results it is concluded that both pilot and post injections result in an increase of unburned hydrocarbon and CO emission and a slight decrease of nitric oxide emissions.

A new tool for SCR (selective catalytic reduction) testing is developed. This side stream test bench has an advantage to test smaller catalysts with a proper exhaust. The exhaust mass flow and temperature are adjustable. A control program is developed to adjust and save the needed parameters. NOx sensors are utilized in the test bench to measure the levels upstream and downstream of SCR reactor. In this study one SCR with a volume of 40.5 dm 3 is tested with exhaust flows ranging from 400 to 600 kg/h and exhaust temperatures from 280 to 360 °C. The tests are conducted using exhaust gas from a medium speed diesel engine running on heavy fuel oil. A decrease from 75% to 99% (depending on test conditions) was observed in NO x over the catalyst. In addition HC and PM were found to decrease while CO was increased over the catalyst. The controlling of exhaust flow and temperature with the test bench succeeded with only minor errors. The measured value of exhaust flow deviated from the set value in the order of 1% and temperature in the order of 0.1%. The results of NOx sensors correlated well with the standardized NOx measurement results with an exception being the case when ammonia slip was formed. When ammonia was found in the exhaust the NOx sensors were observed to misleadingly measure the ammonia as NOx. The results with different exhaust flow rates revealed that SCR was performing better when the flow was lower i.e. the space velocity was lower. At higher temperatures higher NOx conversions were observed. At 360 °C the NOx conversion was near 95% while at 280 °C the conversion was 75%. Copyright © 2012 SAE International.

Low temperature pumpability is an important requirement for engine lubricants. It ensures that sufficient oil reaches the parts of the engine requiring wear protection on engine startup. Until recently, most industry emphasis has been on the low temperature pumpability of the fresh oil. However, the oil can undergo a number of changes during its lifetime in the engine which adversely affect low temperature pumpability. Industry stakeholders are now expressing concerns about the potential risk of engine failures due to deterioration of low temperature pumpability of oils during their life cycle in the engine. Concerns have also been raised over the last few years that the move to Group III base stocks, while improving many of the properties of oil formulations, may also impact their retained low temperature pumpability. The increasing use of biodiesel, particularly when coupled with extended oil drain intervals, has also been shown to impact low temperature pumpability performance of some oils. This paper addresses the effect of emerging trends in lubricants and fuels as well as of the lubricant service cycle and extended drain intervals on retained low temperature pumpability. We first determine the level of ageing of the lubricant in typical field applications as well as in service cycles that tend to lead to low temperature pumpability failure. We show that the loss of low temperature pumpability in the field can be due to a number of different mechanisms, and we explore the contribution of each of these ageing routes to the low temperature pumpability of the lubricant. We show that by carefully matching ageing parameters to those seen in the field we can not only replicate field ageing conditions but also low temperature pumpability behavior.

The influences of ethanol and iso-butanol blended with gasoline on engine-out and post Three-Way Catalyst (TWC) particle size distribution and number concentration were studied using a GM 2.0L turbocharged Spark Ignition Direct Injection (SIDI) engine. The engine was operated using the production ECU with a dynamometer controlling the engine speed and the accelerator pedal position controlling the engine load. A TSI Fast Mobility Particle Sizer (FMPS) spectrometer was used to measure the particle size distribution in the range from 5.6 to 560 nm with a sampling rate of 1 Hz. US federal certification gasoline (E0), two ethanol-blended fuels (E10 and E20), and 11.7% iso-butanol blended fuel (BU12) were tested. Measurements were conducted at ten selected steady-state engine operation conditions. Bi-modal particle size distributions were observed for all operating conditions with peak values at particle sizes of 10 nm and 70 nm. Idle and low speed / low load conditions emitted higher total particle numbers than other operating conditions. At idle, the engine-out Particulate Matter (PM) emissions were dominated by nucleation mode particles, and the production TWC reduced these nucleation mode particles by more than 50%, while leaving the accumulation mode particle distribution unchanged. At engine load higher than 6 barmore » NMEP, accumulation mode particles dominated the engine-out particle emissions and the TWC had little effect. Compared to the baseline gasoline (E0), E10 does not significantly change PM emissions, while E20 and BU12 both reduce PM emissions under the conditions studied. Iso-butanol was observed to impact PM emissions more than ethanol, with up to 50% reductions at some conditions. In this paper, the issues related to PM measurement using FMPS are also discussed. While some uncertainties are due to engine variation, the FMPS must be operated under careful maintenance procedures in order to achieve repeatable measurement results.« less

In this paper, the microscopic spray characteristics of diesel, Rapeseed Methyl Ester (RME) and Gas-to-Liquid (GTL) fuel, were studied at different injection pressures and measuring positions using Phase Doppler Anemometry (PDA) technique and the velocity development and size distributions of the fuel droplets were analysed in order to understand spray atomisation process. The injection pressures ranged from 80MPa to 150MPa, and the measuring position varied from 20mm to 70mm downstream the nozzle. It was found that the data rate is quite low in the near nozzle region and at high injection pressure. Sauter Mean Diameter (SMD) of all fuels obviously decreases when the injection pressure increases from 80MPa to 120MPa; but the injection pressure has little promotion on the axial velocity of droplets. The SMD decreases with increasing axial distance from the nozzle from 40mm to 70mm downstream the nozzle for the given fuels at the injection pressure of 120MPa while relatively stable at 80MPa injection pressure. Moreover, the droplet velocity development of GTL and RME exhibits a similar tendency, compared with that of diesel at given injection pressure. GTL has the smallest SMD, compared with diesel and RME at the given test condition. For RME and diesel, SMD does not show obvious difference at 80MPa injection pressure. However, diesel obtained a smaller SMD when injection pressure was increased to 120MPa. Copyright © 2010 SAE International.

Compressed natural gas (CNG) has been widely used as alternatives to gasoline and diesel in automotive engines. It is a very promising alternative fuel due to many reasons including adaptability to those engines, low in cost, and low emission levels. Unfortunately, when converting to CNG, engines usually suffer from reduced power and limited engine speed. These are due to volumetric loss and slower flame speed. Direct injection (DI) can mitigate these problems by injecting CNG after the intake valve closes, thus increasing volumetric efficiency. In addition, the high pressure gas jet can enhance the turbulence in the cylinder which is beneficial to the mixing and burning. However, conversion to direct fuel injection (DFI) requires a costly modification to the cylinder head to accommodate the direct injector and also can involve piston crown adjustment. This paper discusses a new alternative to converting to DFI using a device called Spark Plug Fuel Injector (SPFI). It is a combination of a fuel injector and a spark plug which fits into the engine block through the existing spark plug hole. With SPFI, conversion to DFI is simple, cheap and requires no modification to the original structure of the engine, except minor calibration to the ECU. The SPFI was installed on a 0.5 liter single cylinder engine and run at 1100 rpm, WOT and stoichiometric air-fuel ratio. Results showed that engine running with SPFI gained the advantage of significant increased volumetric efficiency, faster burning rate, higher output power and improved fuel conversion efficiency compared to port injection operation in the expense of reduced effective compression ratio.

A novel method of measuring cylinder gas temperature in an internal combustion engine cylinder is introduced. The physical basis for the technique is that the flow rate through an orifice is a function of the temperature of the gas flowing through the orifice. Using a pressure transducer in the cylinder, and another in a chamber connected to the cylinder via an orifice, it is shown how the cylinder temperature can be determined with useful sensitivity. In this paper the governing equations are derived, which show that the heat transfer characteristics of the chamber are critical to the performance of the system, and that isothermal or adiabatic conditions give the optimum performance. For a typical internal combustion engine, it is found that the pre-compression cylinder temperature is related to the chamber pressure late in the compression process with sensitivity of the order of 0.005 bar/K. Copyright © 2010 SAE International.

In this paper, results of finite element crash simulation are presented for a TRIP steel side rail with and without considering the phase transformation during forming operations. A homogeneous phase transformation model is adapted to model the mechanical behavior of the austenite-to-martensite phase. The forming process of TRIP steels is simulated with the implementation of the material model. The distribution and volume fraction of the martensite in TRIP steels may be greatly influenced by various factors during forming process and subsequently contribute to the behavior of the formed TRIP steels during the crushing process. The results indicate that, with the forming induced phase transformation, higher energy absorption of the side rail can be achieved. The phase transformation enhances the strength of the side rail

Tube drawing is a well known process involving at room temperature the reduction of diameter and wall thickness to obtain specified values. The initial tube is drawn into a die of a smaller opening and its thickness achieved by use of a mandrel. Usually, the mandrel has a land area which diameter defines by sizing the inside diameter of the final tube. Some structural components found in cars, aircrafts and other vehicles require bent or hydroformed tubes of lower weight. It is of interest to have tubes of varying axial or circumferential thickness so that to reduce overweight in low stressed areas and reinforce it otherwise. However, the production of tubes of varying thickness is more difficult in reason notably of higher metal flow stresses in the deformation zone and the need to control precisely the mandrel position during drawing. Axial thickness variation is obtained using a mandrel with stepped lands or with a slight taper while circumferential variation is achieved with a mandrel of desired internal or external shape (e.g. oval). In this paper, two techniques for axial tube wall thickness variation and one technique for circumferential variations are introduced and tested. First, the techniques to produce drawn tubes with thickness variations are presented. For testing, a small (335 kN) instrumented tube drawing machine is used. Details on this machine, process lubrication, monitored data and on the tooling implemented are also presented. Initial tubes are mainly AA6063 extrusions of 63.5mm O.D. and 2.6mm thick and the final outside diameter, i.e. the inside diameter of the die, is about 47.5 mm. AA6061 tubes are also drawn. Starting with drawing tests without mandrel, the natural flow of the tube and the drawing force involved are measured. Secondly, tubes of 4 different thicknesses are produced with a stepped mandrel and the strain hardening effect on mechanical properties established. Using a tapered mandrel, tubes of continuously varying wall thickness are tested. Higher local pressure in the die corner radius restricts proper lubrication in certain conditions but results are promising in most cases. We also study the effect of thickness rate of change along the tube. Finally, tests with a stepped oval mandrel provided good results for circumferential thickness variations. The dimensional quality is measured using a coordinate measuring machine and mechanical properties obtained from tensile tests in both initial and drawn tubes. Finally, despite some minor problems, the techniques proposed can efficiently produce tubes with thickness variations and have a very strong potential for industrial use.

This paper explores the combined effects of boosting, intake air temperature, trapped residual gas fraction, and dilution on the Maximum Pressure Rise Rate (MPRR) in a boosted single cylinder gasoline HCCI engine with combustion controlled by negative valve overlap. Dilutions by both air and by cooled EGR were used. Because of the sensitivity of MPRR to boost, the MPRR constrained maximum load (as measured by the NIMEP) did not necessarily increase with boosting. At the same intake temperature and trapped residual gas fraction, dilution by recirculated burn gas was effective in reducing the MPRR, but dilution by air increased the value of MPRR. The dependence of MPRR on the operating condition was interpreted successfully by a simple thermodynamic analysis that related the MPRR value to the volumetric heat release rate., United States. Dept. of Energy (University Consortium on Low Temperature Combustion)

This paper explores through engine simulations the use of LPG and CNG gas fuels in a 1.5 liter Spark Ignition (SI) four cylinder gasoline engine with double over head camshafts, four valves per cylinder equipped with a novel mixture preparation and ignition system comprising centrally located Direct Injection (DI) injector and Jet Ignition (JI) nozzles. With DI technology, the fuel may be introduced within the cylinder after completion of the valve events. DI of fuel reduces the embedded air displacement effects of gaseous fuels and lowers the charge temperature. DI also allows lean stratified bulk combustion with enhanced rate of combustion and reduced heat transfer to the cylinder walls creating a bulk lean stratified mixture. Bulk combustion is started by a Jet Ignition (JI) system introducing in the main chamber multiple jets of reacting gases for enhanced rate of combustion, initiating main chamber burning in multiple regions with reduced sensitivity to mixture state and composition. Coupling of JI and DI allows the development of a lean burn engine making possible operation up to main chamber overall fuel-to-air equivalence ratios reducing almost to zero and throttle-less load control by quantity of fuel injected as in the diesel engine. Results are presented in terms of maps of brake specific fuel consumption (BSFC) and efficiency and maximum power densities. Load variations are obtained by varying the air to fuel equivalence ratio from ?=1 up to ?=6.6. Maximum power densities running ?=1 are 80 hp/liter (60 kW/liter) with CNG and almost 90 hp/liter (67 kW/liter) with LPG. BSFCs are as low as 200 and 190 g/kWh and brake efficiencies are up to 39 and 37% respectively with LPG and CNG running lean ?=1.65. Low BSFCs and high brake efficiencies are possible from 25 to 100% of engine load.

An advanced method for LHP evaporator wick manufacturing is suggested. A small-scale loop heat pipe (LHP) with an innovative nickel wick has been fabricated and tested to examine its thermal performances. The LHP container and the tubing of the system are made of stainless steel and two liquids, namely hexane and acetone, have been used as LHP working fluids. The ‘low-cost’ characteristic is given by the reduction of operations which are needed for the LHP wick fabrication. In this study LHP wick was sintered directly inside of the stainless steel tube. Thus the fabrication costs of the LHP wick are less compared with the standard ones for two manufacturing processes: i) compressing the nickel powders and ii) inserting of the wick into the stainless steel tube after the sintering process. Since especially the second process is very delicate and associated to production failures, the present LHP is several times cheaper than the standard LHP. The present paper demonstrates that the novel evaporator wick is still presenting very high performances. A first series of tests including start-up, power ramp up, and power cycle is performed. The experimental results demonstrate the robustness and the feasibility of the innovative LHP. It is found that a heat load of 15 W is needed for a successful start-up. The maximum heat loads is up to 70W for hexane, and 98W is reached for acetone in the steady state operation mode and more then 120W for the periodic mode (20 C condenser temperature, less than 100 C evaporator temperature and with a horizontal orientation of LHP). The hardware model consists of three different objects: (a) the evaporator; (b) a condenser where the heat power is rejected by a simple concentric tube heat exchanger (c) the lines to connect the evaporator and the condenser. A numerical global loop model is also designed by using a well-known lumped parameter code (SINDA/FLUINT). Since the tested LHP is pioneering the standard calculation of the SINDA/FLUINT pre-built system is not suitable and must be completely reconsidered. The model has been tested against experimental data by using hexane as working fluid and a parametric analysis has been run focused on the heat transfer in the evaporator sections and assuming a null quality at the condenser outlet. The mathematical model simulates reasonably well the transient response of the LHP. An accurate heat leak predictions at low powers remain problematic and further experimental tests are necessary, together with a more precise modeling of the condenser.

This paper proposes a method of determining residual gas fraction (RGF) by sampling the CO 2 concentration in the exhaust manifold of a single cylinder HSDI diesel engine. During a skip-fire event, the CO 2 concentration in the exhaust gas for the last firing cycle and the subsequent motoring cycle were measured using a fast-response emissions analyzer. The ratios of these two values are shown to be indicative of the RGF. To simulate the increase in exhaust pressure found with EGR or aftertreatment systems, the exhaust back pressure was elevated using an exhaust throttle. The intake pressure was held constant over a range of engine speed and load conditions. The results demonstrate that the RGF increases linearly with increasing exhaust back pressures for all engine operating conditions. The backflow of exhaust gas into the cylinder and intake manifold during the valve overlap period is found to be the most significant cause of the higher RGFs, especially at higher exhaust back pressures. The measured RGFs are used to validate the results obtained from a commercial 1-D engine flow simulation package. Analysis of the experimental in-cylinder pressure shows the effects of the residual gas on the combustion. With increased RGF, the ignition delay is reduced due to the higher endof-compression temperature caused by the hot residual gases. The offsetting effects of charge dilution on ignition delay are insignificant since the RGF never exceeds 9% of the charge. Pumping losses increase linearly with increasing exhaust back-pressure, reducing net indicated thermal efficiency. However, the gross indicated thermal efficiency is not significantly influenced by exhaust throttling.

Composite layered structures of sound absorptive and barrier materials find frequent use in vehicle NVH control. Developmental transmission loss testing of such composite structures often includes both testing of the barrier material alone and testing of the full composite layered structures. This paper reports on an experimental study of how the method of attachment of the absorptive material to the barrier material influences the transmission loss test results for the composite layered structure and thus the time needed to carry out a series of transmission loss tests.

Recently, several studies conducted by automotive industry revealed the tremendous advantages of Advanced High Strength Steels (AHSS). TRansformation Induced Plasticity (TRIP) steel is one of the typical representative of AHSS. This kind of materials exhibits high strength as well as high formability. Analyzing the crack behaviour in TRIP steels is a challenging task due to the microstructure level inhomogeneities between the different phases (Ferrite, Bainite, Austenite, Martensite) that constitute these materials. This paper aims at investigating the fracture resistance of TRIP steels. For this purpose, a micromechanical finite element model is developed based on the actual microstructure of a TRIP 800 steel. Uniaxial tensile tests on TRIP 800 sheet notched specimens were also conducted and tensile properties and R-curves (Resistance curves) were determined. The comparison between simulation and experimental results leads us to the conclusion that the method using microstructure-based representative volume element (RVE) captures well enough the complex behavior of TRIP steels. The effect of phase transformation, which occurs during the deformation process, on the toughness is observed and discussed.

Tires manufactured from polyurethane (PU) have been espoused recently for reduced hysteretic loss, but the material provides poor traction or poor wear resistance in the application, requiring inclusion of a traditional vulcanized rubber tread at the contact surface. The tread can be attached by adhesive methods after the PU body is cured, or the PU can be directly cured to reception sites on the rubber chain molecules unoccupied by crosslinked (vulcanizing) sulfur atoms. This paper provides a study of the two bonding options, both as-manufactured and after dynamic loading representative of tire performance in service. Models of each process are introduced, and an experimental comparison of the bonding strength between each method is made. Results are applied to tire fatigue simulation.

Exhaust gas recirculation (EGR) cooler fouling has become a significant issue for compliance with NOX emissions standards. This paper reports results of a study of fundamental aspects of EGR cooler fouling. An apparatus and procedure were developed to allow surrogate EGR cooler tubes to be exposed to diesel engine exhaust under controlled conditions. The resulting fouled tubes were removed and analyzed. Volatile and non-volatile deposit mass was measured for each tube. Thermal diffusivity of the deposited soot cake was measured by milling a window into the tube and using the Xenon flash lamp method. The heat capacity of the deposit was measured at temperatures up to 430 C and was slightly higher than graphite, presumably due to the presence of hydrocarbons. These measurements were combined to allow calculation of the deposit thermal conductivity, which was determined to be 0.041 W/mK, only ~1.5 times that of air and much lower than the 304 stainless steel tube (14.7 W/mK). The main determinant of the deposit thermal conductivity is density, which was measured to be just 2% that of the density of the primary soot particles (or 98% porous). The deposit layer thermal resistance was calculated and compared with estimates of the thermalmore » resistance calculated from gas temperature data during the experiment. The deposit properties were also used to further analyze the temperature data collected during the experiment.« less

The present work aims at developing and setting up a methodology in which non-intrusive measurements (engine block vibration) are used for monitoring combustion characteristics (combustion diagnosis, combustion development). The engine block vibration appears as a very complex signal in which different sources can be identified, since every moving component or physical process involved in the operation of the engine produces a vibration signal (exhaust valve open/close, inlet valve open/close, fuel injection, combustion, piston slap). Aimed at monitoring the engine running condition, the information carried by the vibration signal has to be broken down into its various contributions and then they have to be related to their respective excitation sources. Concerning combustion-induced vibration, experimental measures has been at first devoted to the selection of the best location where to place the piezoelectric accelerometer. Such a location has to guarantee the highest sensitivity as regards the combustion structural contribution (due to suddenly applied pressure forces inside the cylinder when combustion process takes place) in the overall engine block vibration signal. A bounded frequency range has been determined, in which high correlation values characterize the relation between the vibration signal and the in-cylinder pressure. A second series of experimental tests has been carried out with the aim of extending the obtained results to the engine complete operative field. In the paper, the experimental apparatus is at first described; then, the time and frequency domain processing technique is presented and representative results of the investigation are reported and discussed (different values of engine speed and load conditions have been imposed).

The work aims at developing and setting up a model able to predict the diesel spray evolution to be integrated into a complete thermodynamic model of the engine. Previous papers have been devoted to realize a numerical model for the injection system, in which a lumped parameter + one-dimensional approach is employed. Such a model has been now enhanced by introducing a quasi-dimensional model for fuel break up, diffusion and penetration processes. A self-developed heating sub-model is included in the model, which enables the evaluation of the influence of the fuel properties on the evaporation process. As a result, the injection system simulation model gives indications on the spray formation process and it is used into a lumped parameter model of the combustion process. Results concerning the influence of fuel properties on the evaporation process are presented and discussed, pointing out its effect on engine performance.

This paper considers the application of die-cast copper rotor induction motors in the drive system of parallel gas/electric hybrid vehicles and compares performance in a realistic driving scenario to that of a permanent magnet motor where efficiency is substantially reduced by PM drag loss. It is concluded from this analysis that the induction machine has a substantial advantage because it can be de-excited when it is not producing torque, eliminating no-load rotational magnetic and electrical loss. Application of die-cast copper rotor traction motors in the hybrid drive system of the latest generation of large U.S. Army severe-duty trucks is then considered. Results of two different electric motor designs are presented, one with a cast aluminum rotor cage and one with a die-cast copper rotor cage. The copper die-cast rotor motor is shown to be 23% lighter and 30% smaller than the aluminum rotor machine.

Rib fractures are the most frequent types of AIS3+ chest injuries and constitute a good indication of severity. However, the behavior of the rib cage is not well documented, and though chest external measurements are often provided in the literature, the strains of the ribs themselves during a crash remain unknown. In order to address this issue, a test protocol was developed, where the ribs of 8 PMHS were equipped with up to 96 strain gauges. In a first series of 3 tests, the subjects were seated upright and their chests were loaded by a 23.4 kg impactor propelled at 4.3 m/s in 0 degrees (pure frontal), 60 degrees (oblique) and 90 degrees (pure lateral) directions. In a second series of 3 tests, the subjects were loaded by the deployment of an unfolded airbag in the same 3 directions. Finally, a third series of 2 tests was performed with airbags at different distances from the subjects, in a pure lateral direction. This paper presents the results of the tests and an analysis of the strain patterns. The differences between a pure frontal, a pure lateral and an oblique loading are explored. The airbag loading is compared to impactor loading and the severity effect is described. Finally, the time and location of the rib fractures are analyzed as a function of the test configuration.

Low-temperature engine oil pumpability has been a concern for OEMs, engine oil formulators, and additive manufacturers for a number of years particularly since a significant number of air-binding failures in 1980 and ’81. On careful investigation of the cause of such field failures, it was found that oil sensitivity to a particular combination of weather conditions was responsible. The experience also suggested that many other lowtemperature weather conditions might produce enginedamaging gelation. Thus, it seemed desirable to develop a bench test that would induce and measure gelation that might form in engine oil by continuously measuring slowly cooling oil over an extensive lowtemperature range. This led to the development of the Scanning Brookfield Technique (SBT) first reported in 1982. With the rapidly growing use of more highly paraffinic, but gelation-prone base oils as well as vegetable oils and fuels, the effects of these components of modern engine oils on oil gelation temperatures and severity are of interest. To effectively address this area of interest, this paper presents the background of the Scanning Brookfield Technique, its basis of developing measures of gelation phenomena called the Gelation Index and Gelation Index Temperature, and initial studies of the factors affecting the formation and growth of the gelation structure.

The paper describes a novel method for calculating the residual gas fraction and the trapping efficiency in a 2 stroke engine. Assuming one dimensional compressible flow through the inlet and exhaust ports, the method estimates the instantaneous mass flowing in and out from the combustion chamber; later the residual gas fraction and trapping efficiency are estimated combining together the perfect displacement and perfect mixing scavenging models. It is assumed that when the intake port opens, the fresh mixture is pushing out the burned charge without any mixing and after a multiple of the time needed for the largest eddy to perform one rotation, the two gasses are instantly mixed up together and expelled. The result is a very simple algorithm that does not require much computational time and is able to estimate with high level of precision the trapping efficiency and the residual gas fraction in 2 stroke engines. The tuning and the validation of this algorithm are performed by measuring the trapping efficiency. These measurements are conducted with an innovative technique which consists in measuring the inlet and exhaust temperature, and calculation of the blow down temperature from the pressure trace. The model was tested using a mini high speed 2 stroke HCCI engine fuelled with diethyl ether between 10,800 and 19,000 [rpm]. (Less)

In this paper, a hybrid combustion mode in four-stroke gasoline direct injection engines was studied. Switching cam profiles and injection strategies simultaneously was adopted to obtain a rapid and smooth switch between SI mode and HCCI mode. Based on the continuous pressure traces and corresponding emissions, HCCI steady operation, HCCI transient process (combustion phase adjustment, SI-HCCI, HCCI-SI, HCCI cold start) were studied. In HCCI mode, HCCI combustion phase can be adjusted rapidly by changing the split injection ratio. The HCCI control strategies had been demonstrated in a Chery GDI2.0 engine. The HCCI engine simulation results show that, oxygen and active radicals are stored due to negative valve overlap and split fuel injection under learn burn condition. This reduces the HCCI sensitivity on inlet boundary conditions, such as intake charge and intake temperature. The engine can be run from 1500rpm to 4000rpm in HCCI mode without spark ignition. The COV of IMEP within and among cylinders are less than 2%. NOx emission is from 0.1 to 2 g/kW.h before TWC. The lowest BSFC is 240g/kW.h at 2000r/min. © 2008 SAE International.

This paper describes how the Cowper-Symonds constitutive equation is used for simulation of vehicle crash. The effects of strain rate sensitivity to the behavior of vehicle structure in material modeling in the frontal impact are investigated. As an illustrative example, a series of impact analyses of the front rail of a vehicle are carried out. The results show that the energy absorption and the loading capacity of the structure are significantly influenced by strain rate. The effects of strain rate to a full-vehicle frontal crash analysis are then investigated. Two analyses are performed with the same FE model. One considers strain rate effect and another without strain rate effect. The results from this study indicate that when incorporating strain rate in the frontal crash analysis, computed crush displacement, velocity, and the deceleration of vehicle are closer to test results than those without strain rate effect.

Microstructure level inhomogeneity between the harder martensite phase and the softer ferrite phase renders the dual phase (DP) steels more complicated failure mechanisms and associated failure modes compared to the conventionally used low alloy homogenous steels. This paper examines the failure mode DP780 steel and DP 980 steel under different loading conditions using finite element analyses on the microstructure levels. Micro-mechanics analyses based on the actual microstructures of DP steel are performed. The two-dimensional microstructure of DP steel was recorded by scanning electron microscopy (SEM). Mechanical properties of the ferrite and martensite phases exhibit the dependency of the different chemistry and thermal mechanical processes. The plastic work hardening properties of the ferrite phase was determined by the synchrotron-based high-energy X-ray diffraction technique. The work hardening properties of the martensite phase were calibrated and determined based on the uniaxial tensile test results. Under different loading conditions, different failure modes are predicted in the form of plastic strain localization. The local failure mode was closely related to the stress state in the material. Under plane stress condition with free lateral boundary, one dominant shear band develops and leads to final failure of the material. However, if the lateral boundary was strictly constrained,more » splitting failure perpendicular to the loading direction is predicted. On the other hand, under plane strain loading condition, commonly observed necking phenomenon is predicted which leads to the final failure of the material. Numerical predictions were well validated by the experimental.« less

Power supply systems play a very important role in applications of everyday life. Mainly, for low power generation, there are two ways of producing energy: electrochemical batteries and small engines. In the last few years many improvements have been carried out in order to obtain lighter batteries with longer duration but unfortunately the energy density of 1 MJ/kg seems to be an asymptotic value. If the energy source is an organic fuel with an energy density of around 29 MJ/kg and a minimum overall efficiency of only 3.5%, this device can surpass the batteries. Nowadays the most efficient combustion process is HCCI combustion which is able to combine high energy conversion efficiency and low emission levels with a very low fuel consumption. In this paper, an investigation has been carried out concerning the effects of the compression ratio on the performance and emissions of a mini, Vd me 4.11 [cmu3], HCCI engine fueled with diethyl ether. Because of its high reactivity, autoignition of the mixture was achieved only using compression energy. The compression ratio was changed by altering the squish distance: 0.25, 0.50, 0.75, 1.00 and 1.25 [mm]. For each compression ratio, three sets of measurements were performed: 3000, 7000 and 12000 [rpm]. The study showed that diethyl ether was only slightly affected by quenching problems when the squish distance was 0.25 and 0.50 [mm] at 7000 [rpm]. It was also demonstrated that the performance improved when decreasing the compression ratio to an optimum point and subsequently dropped to zero when the highest spacer, 1.25 [mm], was used. Due to a very low combustion and thermodynamic efficiencies, the specific emissions of CO and HC were one order of magnitude higher than for a normal car/truck engine, whereas NOx emissions were comparable to those of a conventional diesel engine. Finally, the study rendered it possible to understand how much an HCCI engine fueled with diethyl ether could be scaled down since it was shown that this fuel was not very sensitive to quenching, with a squish distance of 0.25 [mm]. (Less)

Pressure-sensitive film embedded into the body of a pad friction compound is a unique technique used to measure the dynamic center of pressure at the pad/disc interface during a normal braking operation. This paper uses of a modified 12 piston opposed caliper where the initial center of pressure may be varied both along the pad and radially. Results show a very definite movement of the center of pressure towards the center of the pad as the brake pressure is increased. In addition it is seen that a leading center of pressure (CoP) will result in noise whereas a trailing CoP gives a quiet brake. Equally a CoP towards the inner edge of the pad increases noise propensity whereas towards the outer edge a quiet brake. The results also show little influence on the CoP with disc speed.