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This paper contains the results of studies of self-ignition of differently-structured hydrocarbons, as well as of different gasolines, under varying rates of compression. Two oxygen-containing compounds, methanol and ether, were also examined. The air-fuel equivalence ratio was held at 1.2 for all tests. The experimental conditions simulate the end-gas state in an engine where compression takes place at different rates when engine speed is changed. Using the modern concept of the gas-phase oxidation of hydrocarbons, and drawing on the experimental data, a new scheme of hydrocarbon oxidation was developed. The activation energy for five individual hydrocarbons was calculated according to this scheme. The experiments with different gasolines have shown that the presence of more than 30% aromatic or olefinic hydrocarbons in gasoline leads to independence of fuel-knock resistance from engine speed. This last fact can promote high-speed knock.

The effects of fuel sulfur concentration on heavy-duty diesel emissions have been studied at two EPA steady-state operating conditions, mode 9 (1900 RPM, 75% Load) and mode 11(1900 RPM, 25% Load). Data were obtained using one fuel at two sulfur levels (Low Sulfur, LS = 0.01 wt% S and Doped Low Sulfur DS = 0.29 wt% S). All tests were conducted using a Cummins LTA10-300 heavy-duty diesel engine. No significant changes were found for the nitrogen oxides (NOx), soluble organic fractions (SOF) and XAD-2 (a copolymer of styrene and divinylbenzene) organic component (XOC) due to the fuel sulfur level increase at either engine mode. The hydrocarbon (HC) levels were not significantly affected by sulfur at mode 9; however, at mode 11 the HC levels were reduced by 16%. The total particulate matter (TPM) levels increased by 17% at mode 11 and by 24% at mode 9 (both significantly different).

Fuel temperature in the injector of small direct injection gasoline engine is high. On some conditions it is higher than saturated temperature. Over saturated temperature spray characteristics greatly change. In order to predict in-cylinder phenomena accurately, it is important to understand spray behavior and mixture process above saturated temperature. Therefore spray shape, mixture formation process and Sauter mean radius were (SMR) measured in a constant volume chamber. And based on the measurement result initial spray boundary conditions were arranged so that spray characteristics over saturated temperature could be represented by using CFD code KIVA-3[1]. Moreover KIVA-3 code was combined with detailed chemical kinetics code Chemkin II to predict combustion products. [2] Calculated combustion process was validated with visualization of chemiluminescence. As a result, spray shape and penetration length have good agreement with measured ones for each fuel temperature.

Piston wetting can be isolated from the other sources of HC emissions from DISI engines by operating the engine predominantly on a gaseous fuel and using an injector probe to impact a small amount of liquid fuel on the piston top. This results in a marked increase in HC emissions. All of our prior tests with the injector probe used California Phase 2 reformulated gasoline as the liquid fuel. In the present study, a variety of pure liquid hydrocarbon fuels are used to examine the influence of fuel volatility and structure. Additionally, the exhaust hydrocarbons are speciated to differentiate between the emissions resulting from the gaseous fuel and those resulting from the liquid fuel. It is shown that the HC emissions correspond to the Leidenfrost effect: fuels with very low boiling points yield high HCs and those with a boiling point near or above the piston temperature produce much lower HCs.

A mileage accumulation dynamometer (MAD) facility capable of running four vehicles continuously has been upgraded to provide a useful tool to evaluate the deposit control performance of fuels and fuel additives. Road cycles were recorded and repeated in this facility consistently. An optimized driving test cycle and testing duration have been developed to represent the field performance of fuels and vehicles. This tool was used in a large testing program to evaluate the intake valve and combustion chamber deposit control capability of several premium gasolines, produced by major fuel suppliers in the U.S. Four high production volume vehicle models were included in the program. Results indicate that the level of deposits is a strong function of the engine type. Differences in engine design can result in considerable differences in valve and combustion chamber deposits. The study also demonstrates that existing fuels in the market affect the levels of engine deposits significantly.

The effect of fuel changes on diesel oxidation catalyst performance was studied by comparing the physical, chemical and biological character of the particulate emissions using three different fuels. Baseline (uncatalyzed) emissions were also compared for these same fuels. The fuels used for this study were: a typical No. 2 fuel, a No. 1 fuel, and a shale oil-derived diesel fuel. Comparisons of NOX, NO, NO2, HC and particulate mass emissions using each fuel were made using selected modes from the EPA 13 mode cycle. Changes in the chemical and biological character of the soluble organic fraction (SOF) were also studied. Fuel properties, most notably fuel sulfur content, were found to affect the performance of the oxidation catalyst used. Fuel sulfur content should be kept as low as possible if catalytic converters are used on diesel powered equipment.

To meet future particulate number regulations, one path being investigated is higher fuel pressures for direct injection systems. At operating pressures of 30 MPa to 40 MPa, the fuel system components must be designed to withstand these pressures and additional power is required by the pump to pressurize the fuel to higher pressures than the nominal 15MPa to 20MPa in use today. This additional power to the pump can affect vehicle fuel economy, but may be partially offset by increases in combustion efficiency due to improved spray mixture preparation. This paper examines the impact on fuel economy from increased system fuel pressures from a combination of test results and simulations. A GDi pump and valvetrain model has been developed and correlated to existing pump torque measurements and subsequently used to predict the increase in torque and associated impact on fuel economy due to higher GDi system pressures.

This study evaluated multi-layer steel and composite head gaskets of various thicknesses (0.43 to 1.5 mm) and fire-ring diameters to determine the influence of head gasket crevices on engine-out hydrocarbon (HC) emissions. The upper limit in the percent reduction in HC emissions from gasket-design modifications is estimated to be about 15%. At part-load conditions, the lowest HC emissions were measured for head-gasket thickness of about 1 mm. Significantly smaller thicknesses of the order of 0.4 mm result in an increase in HC emissions. Substantial hydrocarbon-emissions advantage may be realized by minimizing the gasket-to-cylinder bore offset.

Child restraint head padding is designed for the child's comfort under normal use. Under vehicle crash conditions, however, the padding in a rear facing child restraint may not be designed to sufficiently absorb impact energy. The objective of this paper is to evaluate the effects of various head padding conditions in rear facing child restraints in frontal impacts. Five sled tests were performed to measure the response of a CRABI 12 month dummy to different padding conditions in a rear facing child restraint. Static loading tests were performed on the padding materials. Results show that using padding of low stiffness increases head acceleration and HIC15 values.

With the development of the addition-type polyimide resins, a need arose for a coupling agent that would improve the performance of the fiber-resin interface under thermal stress. Research work was carried out to develop such a material and resulted in a new coupling agent for use at high temperatures. The test data generated from glass fiber reinforced composites using this new coupling agent, and the study of the interface using the scanning electron microscope, demonstrate an improvement in the cohesive and interfacial shear of the glass fiber-resin matrix. This development has provided the designer with a material that retains its structural integrity under extreme thermal conditions.

The following paper describes the operational experience of using blended or heavy fuels for inland marine service. The experience outlined here is with a vessel retrofitted to specifically use 2000 Redwood No. 1, seconds, fuel and designed to increase blended fuel-oil viscosity rising as high as 3500 Redwood. An engine teardown was performed and no abnormal wear was noticed.

To aid in better assessing the corrosion performance of AZ91 die cast magnesium, standard salt spray corrosion tests have been made on both randomly selected commercial die castings and on three series of controlled purity test panels. The results reveal that the poor performance often associated with magnesium parts in salt spray are due principally to iron, nickel, and copper contamination levels. When these contaminants were limited, severe pitting corrosion was eliminated and the salt spray performance was good to excellent when compared to 380 aluminum and cold rolled steel.

The emission of nanoparticles from combustion engines has been shown to have a poorly understood impact on the atmospheric environment and human health, and legislation tends to err on the side of caution. Researchers have shown that Gasoline Direct Injection (GDI) engines tend to emit large amounts of small-sized particles compared to diesel engines fitted with Diesel Particulate Filters (DPFs). As a result, the particulate number emission level of GDI engines means that they could face some challenges in meeting the likely EU6 emissions requirement. This paper presents size-resolved particle number emissions measurements from a spray-guided GDI engine and evaluates the performance of an Evaporation Tube (ET). The performance of an Evaporation Tube and hot air dilution system with a 7:1 dilution ratio has been studied, as the EU legislation uses these to exclude volatile particles.

Hydrogen assisted jet ignition (HAJI) is a pre-chamber ignition system for standard gasoline fueled engines that involves the use of a chemically active turbulent jet to initiate combustion in lean fuel mixtures. HAJI burns the lean main charge rapidly and with almost no combustion variability, which allows for low hydrocarbon emissions and almost zero NOx, due to lower peak temperatures. This paper focuses on the effects of internal and cooled external exhaust gas recirculation (EGR) on combustion parameters, emissions and thermal efficiency in a single cylinder HAJI equipped CFR engine. Experimental results indicate that replacing air with EGR in λ=2 mixtures can shift the lean limit at which NOx is negligible to mixtures as rich as λ=1.3, without a large penalty in hydrocarbon emissions and thermal efficiency.

The effect of hydroforming on the mechanical properties and dynamic crush behaviors of tapered aluminum 6063-T4 tubes with octagonal cross section are investigated by experiments. First, the thickness profile of the hydroformed tube is measured by non-destructive examination technique using ultrasonic thickness gauge. The effect of hydroforming on the mechanical properties of the tube is investigated by quasi-static tensile tests of specimens prepared from different regions of the tube based on the thickness profile. The effect of hydroforming on the dynamic crush behaviors of the tube is investigated by axial crush tests under dynamic loads. Specimens and tubes are tested in two different heat treatment conditions: hydroformed-T4 (as-received) and T6. The results of the quasi-static tensile tests for the specimens in hydroformed-T4 condition show different amounts of work hardening depending on the regions, which the specimens are prepared from.

An experimental investigation was carried out to assess the effect on engine operation of the addition of 20% hydrogen by volume to natural gas. Blends of hydrogen and natural gas are referred to as hythane in this report. Three groups of testing were conducted. All the tests were conducted at light loads similar to those in urban driving. The first group of tests were conducted using a 2.0 liter Nissan four cylinder engine to measure the increase in flame front propagation rate when fueled with hythane as compared to pure methane (simulating natural gas). The second group of tests were conducted with a 1.6 liter Toyota four cylinder engine to measure the changes in emissions and thermal efficiency comparing hythane operation to pure methane operation.

High hydrogen containing atmospheres, such as endothermic gas and dissociated ammonia, effectively remove much of the sulfur that is added to ferrous compacts for machinability. Sulfur loss was found to decrease with lower hydrogen concentrations in the atmosphere. The high hydrogen sulfide concentrations present with high hydrogen atmospheres will reduce the life expectancy of the metal components in the furnace. Low hydrogen concentrations in the atmosphere produce little hydrogen sulfide and expected belt and muffle life will significantly increase. Additions of water to the sintering atmosphere did not appear to have a significant effect on the sulfur content of the compacts.

In order to realize the high compression ratio and high dilution combustion toward improvement in thermal efficiency, the improvement in stability of ignition and initial phase of combustion under the high gas flow field is the major challenge. In terms of the shift on the higher power side of the operating point by downsizing and improvement of real world fuel consumption, the improvement of ignitability is increasingly expected in the wide operating range also including high load and high engine speed region. In this study, the effects of the gas pressure, gas flow velocity near the spark gap at ignition timing, and discharge current characteristics on spark channel formation were analyzed, focusing on restrike event and spark channel stretching in the spark channel formation process. And the relationship between the average discharge current until 1 ms and the EGR combustion limit was considered.

The effects of ignition location on combustion duration, thermal efficiency, exhaust emissions, cyclic variability, and knock sensitivity were investigated in two premixed-charge spark-ignition engines with disk-shaped combstion chambers and having high levels of swirlu. Except for very lean high-swirl conditions, peripheral ignition produced a longer combustion duration than did central ignition, but the difference was less than expected from geometric considerations alone. Flame holding at the spark electrodes, observed in high-speed schlieren films, enhances mass-burning rates for off-center ignition locations. For a swirl number of 4 no significant differences with ignition location were measured in thermal efficiency, heat-transfer losses, exhaust temperature, cyclic variability, or exhaust emissions, but with peripheral ignition the engine had a greater knock sensitivity, lower knock-1imited peak power, and a misfire problem of unidentified origin.

This report presents results from a performance evaluation study on the adequacy of the image size, within school bus cross view mirrors, mandated by FMVSS 111 The mandated image size is 9X3 minutes of arc (ie, 9′X3′) Six observers discriminated the orientation offset of three different image sizes (ie, 45′X15′, 9′X3′, 13.5′X45′) presented onto a banana type cross view mirror. The images were presented to observers under three luminance contrast levels 15%, 20%, and 25%. Results indicated that poor performance was associated with the 45′X15′ image size at all contrast levels and the 9′X3′ image size at a luminance contrast of 15%. The 135′X45′ image size was associated with good performance. In conclusion, measures of performance failed to demonstrate an unequivocal deficiency of the 9′X3′ image size.