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Fatigue life predictions for notched components are typically based on constant amplitude fully reversed strain-life data derived from smooth specimens. A mean stress parameter is applied to account for the effects of mean stress in the crack initiation location. Fatigue life predictions using this approach are usually accurate for constant amplitude fatigue but are almost always unconservative for variable amplitude service loading. A considerable amount of work has now related the unconservative predictions to reductions in crack closure during the large cycles in the variable amplitude load history which result in lower crack opening stresses for the small cycles than those in the constant amplitude reference tests used in design. This increases the effective strain range and the damage done by the small cycles and results in shorter than predicted fatigue lives.

We forced biodiesel to oxidize and heated biodiesel to accelerate its oxidation at about 110° for 10 days. Total particle number and size distribution were investigated in unoxidized and oxidized biodiesel blend fuels. To better understand the effect of biodiesel blends on nano particulate emissions, steady state tests were conducted on a heavy-duty diesel engine. The engine was fueled with Ultra Low Sulfur Diesel (ULSD), a blend of 10% biodiesel derived from waste cooking oil on volumetric basis, equipped with a common rail direct injection system and turbocharger, lives up to the requirements of EURO III. Particle number and size distribution of the diesel engine were obtained by using an Engine Exhaust Particle Sizer (EEPS) and the dilution temperature was maintained around 150° (±5) to avoid condensation of particles. The experimental results show that NOx increase and PM (Particulate Matter) decrease for unoxidized biodiesel blend fuel in comparison to ULSD.

This paper presents the results of emission tests of a flexible fuel vehicle (FFV) powered by an SI engine, fueled by M85, and supplied with oxygen-enriched intake air containing nominal 21%, 23%, and 25% oxygen (by volume). Emission data were collected by following the standard federal test procedure (FTP) and U.S. Environmental Protection Agency's (EPA's) “off-cycle” test EPA-REP05. Engine-out total hydrocarbons (THCs) and unburned methanol were considerably reduced in the entire FTP cycle when the oxygen content of the intake air was either 23% or 25%. However, CO emissions did not vary appreciably, and NOx emissions were higher. Formaldehyde emissions were reduced by about 53% in bag 1, 84% in bag 2, and 59% in bag 3 of the FTP cycle when 25% oxygen-enriched intake air was used.

A study was performed in which the effects on the regulated emissions from a commercial small DI diesel engine were measured for different refinery-derived fuel blends. Seven different fuel blends were tested, of which two were deemed to merit more detailed evaluation. To investigate the effects of fuel properties on the combustion processes with these fuel blends, two-color pyrometry was used via optically accessible cylinderheads. Additional data were obtained with one of the fuel blends with a heavy-duty DI diesel engine. California diesel fuel was used as a baseline. The fuel blends were made by mixing the components typically found in gasoline, such as methyl tertiary-butyl ether (MTBE) and whole fluid catalytic cracking gasoline (WH-FCC). The mixing was performed on a volume basis. Cetane improver (CI) was added to maintain the same cetane number (CN) of the fuel blends as that of the baseline fuel.

Exhaust gas recirculation (EGR) has been employed in a diesel engine to reduce NOx emissions by diluting the fresh air charge with gases composed of primarily N2, CO2, H2O, and O2 from the engines exhaust stream. The addition of EGR reduces the production of NOx by lowering the peak cylinder gas temperature and reducing the concentration of O2 molecules, both of which contribute to the NOx formation mechanism. The amount of EGR has been typically controlled using an open loop control strategy where the flow of EGR was calibrated to the engine speed and load and controlled by the combination of an EGR valve and the ratio of the boost and exhaust back pressures. When oxygenated biofuels with lower specific energy are used, the engine control unit (ECU) will demand a higher fuel rate to maintain power output, which can alter the volumetric flow rate of EGR. In addition, oxygenated biofuels affect the oxygen concentration in the intake manifold gas stream.

A test program has been completed to evaluate the performance of late model passenger cars using a variety of oxygenated fuel blends. The tests were conducted using the Coordinating Research Council (CRC) intermediate temperature drivability test procedure. The program involved the use of sixteen 1983 and 1984 model vehicles that were selected to represent a variety of engine sizes, fuel system types, emission system configurations, and auto manufacturers. Two trained drivers were used to test these cars with 15 different fuels. The fuels consisted of three volatility classes with each including a hydrocarbon-only gasoline and blends with methanol and ethanol at the 3.7 percent oxygen level. In blends involving methanol, gasoline-grade tertiary butyl alcohol (GTBA) was used as a cosolvent. Statistical analysis of the resulting test data showed that, as a group, the cars tested were insensitive to the addition of this level of oxygenates to the fuels.

Catalyst deterioration caused by phosphorus-containing engine oil additives was investigated using a variety of engine oil blends in a steady-state engine-dynamometer test. The reductions in hydrocarbon and carbon monoxide conversion in the 200-hour test were related to two parameters: 1) the quantity of phosphorus in the oil added to the engine, and 2) the amount of phosphorus on the catalyst at the end of the test. Catalyst degradation relative to the first parameter differed from that relative to the second because the two parameters were not directly related. Specifically, catalyst conversion efficiency decreased nonlinearly with the amount of oil-derived phosphorus added to the engine, but linearly with the amount of oil-derived phosphorus found on the catalyst. A higher percentage of phosphorus added to the engine was found on the catalyst with oils containing tricresylphosphate (TCP) than with oils containing zinc dialkyldithiophosphate (ZDP).

The effects of physical factors on ignition delay have been studied on a motored research engine using a single injection technique. The fuels used included a high cetane number reference fuel, gas oil and M. T. 80 petrol. The primary factors investigated are those pertaining to the fuel spray, such as injection timing, quantity, and pressure (affecting drop size, velocity and injection rate); hole diameter (affecting drop size and injection rate) and spray form (nozzle type); and those pertaining to the engine, such as temperature, pressure and air velocity. Engine operating variables such as speed and load affect the ignition delay because they change the primary factors such as injection pressure, compression temperature, pressure and air velocity. It has been found that under normal running conditions, compression temperature and pressure are the major factors. All other factors have only secondary effects.

The effects of changes in the cetane number of diesel liquid pilot fuels on the ignition delay period in dual fuel engines were investigated experimentally. Different pilot fuel quantities were employed with commercially pure methane, propane and low heating value gaseous fuel mixtures of methane with nitrogen or carbon dioxide over a range of engine load. The ignition delay variation with increased gaseous fuel admission showed a strong dependance on both the quantity and the quality of the pilot fuel used. It was found that the use of high cetane number pilot liquid fuels permitted smaller pilot quantities to be used satisfactorily. Engine operation on propane and low heating value gaseous fuels improved in comparison with dual fuel engine operation employing common diesel fuels.

Dimethyl-ether combustion with pilot injection was investigated in a single cylinder direct injection diesel engine equipped with a common-rail injection system. Combustion characteristics and emissions were tested with dimethyl-ether and compared with diesel fuel. The main injection timing was fixed to have the best timings for maximum power output. The total injected fuel mass corresponded to a low heating value of 405 joules per cycle at 800 rpm. The fuel quantity and the injection timing of the pilot injection were varied from 8 to 20% of the total injected mass and from 50 to 10 crank angle degrees before the main injection timing, respectively. Ignition delay decreased with pilot injection. The effects of pilot injection were less significant with DME combustion than with diesel. Pilot injection caused the main combustion to increase in intensity resulting in decreased emissions of hydrocarbons, carbon monoxide and particulate matter.

The spark ignition (SI) engine has been known to exhibit several different abnormal combustion phenomena, such as knock or pre-ignition, which have been addressed with improved engine design or control schemes. However, in highly boosted SI engines, Low-Speed Pre-Ignition (LSPI), a pre-ignition event typically followed by heavy knock, has developed into a topic of major interest due to its potential for engine damage. Previous experiments associated increases in hydrocarbon emissions with the blowdown event of an LSPI cycle [1]. Also, the same experiments showed that there was a dependency of the LSPI activity on fuel and/or lubricant compositions [1]. Based on these findings it was hypothesized that accumulated hydrocarbons play a role in LSPI and are consumed during LSPI events. A potential source for accumulated HC is the top land piston crevice.

Automobile engines have undergone continuous improvements over the years in terms of higher output, lower pollutant emission, and lower fuel consumption. With recent steep rise in crude oil price, consumer interest in fuel economy of automobiles has increased. With such interest, lowering fuel consumption appears to be the issue that currently needs to be tackled. The piston ring and piston friction were measured with floating liner, we confirmed that wear of piston ring running surface influenced friction. It was confirmed by this study that main cause of break in is decrease in liner surface roughness and piston ring OD wear. Additionally, this paper indicated that friction decreased by preventing piston ring OD wear in the process of break in.

The current work utilizes computational fluid dynamics (CFD) simulations to assess the effects of different piston geometries in an active-type pre-chamber combustion engine fueled with methane. Previous works identified that the interaction of the jets with the main chamber flow and piston wall are key aspects for the local turbulent flame speed and overall burning duration. The combustion process is simulated with the G-equation model for flame propagation combined with the MZ-WSR model to determine the post-flame composition and to predict possible auto-ignition of the reactant mixture. Four setups were considered: two bowl-shaped and one flat piston, and one additional case of the flat piston with jets at wider jet angles to the cylinder axis. The results show that premature jet-wall interaction impacts the main chamber pressure build-up, turbulence, and burn rate.

This paper reports results from a quantitative study on the effects of diesel piston temperature and fuel sulfur on piston deposits. Tests were conducted in a fourcycle, turbocharged single-cylinder engine using uncompounded oils and distillate fuel. This fundamental study demonstrated that at constant exhaust smoke, piston temperature between 200°C to 260°C is the primary factor in controlling piston top groove deposit formation. The activation energy for this process was determined to be 12 kcal/mole, which is within the normal range of chemical reactions. The rate of top groove deposit formation doubled for every 30°C rise in piston temperature. Piston temperature also increased total piston deposits on all grooves and lands. Fuel sulfur in the range of 0 to 1.0 wt % had no effect on top groove deposit formation, although it did increase lower groove and lower land deposits. Crankcase oil oxidation appeared to correlate with piston temperature.

Alternatives to cadmium plating on fasteners are investigated from the point of view of cost, corrosion resistance, torque/tension relationships and vibration resistance. Conclusions show that these are inter-related and point to the direction to be taken dependant on the criteria of the fastened joint under consideration.

A laboratory study was performed to assess the contributions of platinum and rhodium to the emissions performance of a lean NOx trap. Samples of a barium-only formulation were obtained with either 0.84 g/L of platinum, 0.51 g/L of rhodium, or 1.0 g/L of platinum and rhodium in ratios of 1/0/1 or 5/0/1. 60 s lean/5 s rich tests were performed on fresh samples and samples that were aged on high temperature durability cycles. The results indicate that platinum is necessary for the NOx storage performance of the trap at low temperatures (e.g., 250°C), whereas rhodium is needed for the NOx reduction capability and consequently the purgability of the trap at low temperatures. As a result, the bimetallic Pt/Rh samples provided the best overall NOx conversion at low temperatures fresh and after aging.

The simulation of heat exchanger air flow characteristics in a sub-scale wind tunnel test requires an accurate representation of the full-scale pressure drop across the element. In practice this is normally achieved using laminations of various porous materials and honeycombs on the basis of experience and ad hoc data. In view of this, a series of measurements of the pressure drop, in both the near and far field, across screens with porosity (β) in the range 0.41 ≺ β ≺ 0.76 are reported. The aim being to establish a relationship between the porosity and the pressure drop characteristics of a given material at various angles of inclination to the free-stream flow. Furthermore, the effect of screen depth was investigated using honeycombs. This data will facilitate detailed design and accurate representation of the flow characteristics at sub scale.

The effects of port fuel injection (PFI) timing and targeting on air/fuel (A/F) control, exhaust emissions, and combustion stability at retarded spark timing were investigated on a 2.0L I-4 engine with production injectors (300-350 micron SMD droplet spray). Timings were fully closed valve injection (CVI) or fully open valve injection (OVI), and selected targetings were towards the valve or port floor. An “ideal” pre-vaporized, pre-mixed fuel system was also tested to provide a baseline with which to isolate PFI fuel preparation effects. The key findings were: Transient A/F excursions with PFI were minimized over the full temperature range with OVI timing and valve targeting. The X-tau modeled film mass for OVI/valve target was 50% less than CVI/valve target and 30% less than OVI/port target with a cold engine (20° C). When fully warm (90° C), the A/F response of CVI/valve target improved to near that of OVI.

In this study, the thorax and the abdomen of nine subjects were imaged in four postures using a positional MRI scanner. The four postures were seated, standing, forward-flexed and supine. They were selected to represent car occupants, pedestrians, cyclists and a typical position for medical imaging, respectively. Geometrical models of key anatomical structures were registered from the imaging dataset using a custom registration toolbox. The analysis of the images and models allowed the quantification of the respective effects of posture and subject-to-subject variation on the position, shape and volume of the abdominal organs, skeletal components and thoracic cavity. In summary, except for the supine posture, the organ volumes and their positions in the spinal frame were mostly unaffected by the posture.

Six electronic needle-display speedometers from five different manufacturers were tested in order to determine the behavior of the gauges following a power interruption and impact. Subject motorcycles were accelerated to pre-determined speeds, at which point the speedometer wiring harness was disconnected. The observed results were that the dial indicator would move slightly up, down, or remain in place depending on the model of the speedometer. The observed change of indicated speed was within +/- 10 mph upon power loss. Additionally, the speedometers were subjected to impact testing to further analyze needle movement due to collision forces. Speedometers were attached to a linear drop rail apparatus instrumented with an accelerometer. A minimum acceleration due to impact which could cause needle movement was measured for each speedometer assembly.