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This paper describes an investigation of emissions from an engine featuring variable valve timing, a swirlcontrol valve and exhaust gas recirculation. Design of experiments has been used to model the response of hydrocarbons and other emissions to the engine operating variables. The experiments identified the potential of VVT for simultaneous NOx, and HC reduction. The type of experiment employed was the Central Composite Rotatable Design; this is a fractional factorial design that maximises the amount of information obtained from a minimal number of test runs. A Fast Response Flame Ionisation Detector has been used to clarify the reasons for the effect of inlet and exhaust VVT on hydrocarbons.

Gasoline properties have changed over the years. The first changes were made to comply with federal and later ASTM gasoline specifications. Beginning in 1960, limitations were placed on gasoline properties to help reduce air pollution. The state of California has led the nation in limiting gasoline properties to improve ambient air quality. The Clean Air Act Amendments of 1990 increased the federal government's role in controlling the properties of gasoline. Wintertime oxygenated gasoline was introduced in 1992 in specified areas with carbon monoxide concerns. Reformulated gasoline was introduced in 1995 in areas of the United States with severe ozone concerns. The strictest control of gasoline properties to date occurred in 1996 when California Phase 2 reformulated gasoline was required.

Lubricity testing of reformulated diesel fuels (sulfur <0 005 w-%, aromatics <20 vol-%) was started in 1990. A 1000 hour in-house test rig with distributor pumps was used for testing fuels and additives. When lubricity is not adequate, excessive wear is seen in the pump. A field test on 140 buses each accumulating 150 000 - 250 000 km with reformulated diesel was carried out. Reformulated diesel has been on the market since 1993 without problems. Lubricity was evaluated with HFRR test and compared to the pump rig results. HFRR overestimated the need for lubricity additives. Fuel sulfur was found to be not the only indicator of lubricity and lubricity of low sulfur diesel was as good as high sulfur when other fuel parameters were kept constant.

Today's lubricant quality is defined by classifications, or specifications, that are established by taking into account metallurgy, equipment design, and or operating conditions For engine oils, the American Petroleum Institute (API), the Society of Automotive Engineers (SAE), and the American Society for Testing and Materials (ASTM) are the key bodies that define industry needs, establish classifications, and develop test methods to assure that lubricants meet the required performance For gear oils, API and the Coordinating Research Council (CRC) play a similar role The U S Military and original equipment manufacturers (OEMs) have their own performance requirements that are usually over and above those of the API/SAE/ASTM and API/CRC The performance requirements of automatic transmission fluids (ATFs) are established by OEMs, such as General Motors Corporation (GM) and the Ford Motor Company Greases are defined by the National Lubricating Grease Institute's (NLGI) classification system The paper follows the history of automotive lubrication from the early 1900s to date It describes the introduction and progression of classifications and specifications with changes in the lubricating environment

The effect of diesel cetane number, total aromatic content T90, and fuel nitrogen content on regulated emissions (HC, CO, NOx, and PM) from a 1991 DDC Series 60 engine were measured Emissions tests were conducted using the EPA heavy-duty transient test (CFR 40 Part 86 Subpart N) at a laboratory located 5,280 feet (1609 m) above sea level. The objective of this work was to determine if the effect of fuel chemistry at high altitude is similar to what is observed at sea level and to examine the effect of specific fuel chemistry variables on emissions. An initial tea series was conducted to examine the effect of cetane number and aromatics. Transient emissions for this test series indicated much higher (50 to 75%) particulate emissions at high altitude than observed on the same model engine and similar fuels at sea level.

Tumble flow has been recognized as an important and positive enhancement of combustion for SI engines. Tumble flow modeling with quasi-dimensional models is difficult because of the transient nature of tumble vortex, compared with swirl flows. Although multi-dimensional models have obtained plenty of attention recently in engine research, quasi-dimensional SI engine models will continue to dominate industrial applications in the near future. In the present research, a bulk flow model has been developed for tumble flows based on angular momentum conservation. Its effect on turbulence was then modeled using a Two-Equation Model (k-ε Model). A methodology has also been developed to use particle tracking velocimetry (PTV) measurement to calibrate the quasi-dimensional bulk flow model at engine BDC to model tumble vortex and tumble-generated turbulence. The Entrainment Combustion Model was used for combustion modeling.

To help predict hydrocarbon emissions during cold-start conditions we are developing a numerical model for the dynamics and vaporization of the liquid wall films formed in port-injected spark-ignition engines and incorporating this model in the KIVA-3 code for complex geometries. This paper summarizes the current status of our project and presents illustrative example calculations. The dynamics of the wall film is influenced by interactions with the impinging spray, the wall, and the gas flow near the wall. The spray influences the film through mass, tangential momentum, and energy addition. The wall affects the film through the no-slip boundary condition and heat transfer. The gas alters film dynamics through tangential stresses and heat and mass transfer in the gas boundary layers above the films. New wall functions are given to predict transport in the boundary layers above the vaporizing films.

A computational fluid dynamics study of the internal flow and the combustion process within two different spark ignition engines has been carried out. Numerical simulations have been performed with the Kiva-II code using an ignition model taking into account the velocity field in the spark plug area and the coherent flame model. This modeling approach was successfully validated in single cylinder research engine under various operating conditions and then was applied in a four valve pent roof production engine. The location and magnitude of heat releases, flame areas and temperature distributions were visualized and analyzed for all cases. The characteristics of these models were also addressed by examining the influence of different engine parameters: speed, load, air-fuel ratio, spark ignition timing. The results were compared with experimental studies including laser Doppler velocimetry, in-cylinder pressure measurements and combustion velocity.

The purpose of this study is to determine if inhomogeneous mixing of EGR and fresh air in the intake ports can lead to a specific spatial distribution of burnt gases in the combustion chamber before ignition. To achieve this goal, several three dimensional computations of a multi-valve, spark ignited engine with a dual intake ports are performed. We study the effect of engine speed (1500 and 3000 rpm), the effect of flow structure and turbulence (one and two operating intake valves) and the effect of the EGR intake technology (in the plenum or in each intake runner). Three dimensional computations are performed with a new version of the KMB code. Numerical improvements (iterative solver. convection scheme …), new sub-models (turbulence, beat transfer and law of the wall), as well as a multi-block strategy with mesh refinement algorithm were developed and implemented in the code. These improvements allow complicated geometries to be modeled.

The effects on engine-out HC emissions of a premixed propane system, and three PFI systems employing different types of injectors and using Phase II gasoline were investigated on a four-cylinder DOHC spark-ignition engine. Cold conditions resulted in significant increases in engine-out HC emissions. Phase II gasoline caused much higher emissions of HC than propane fuel. The difference in the HC emissions from the two fuels increased dramatically with lowering the coolant temperature of the engine. At cold conditions, liquid fuel entering the combustion chamber appears to be the primary source of engine out HC emissions. At the coldest temperature tested the estimated percent contribution of in-cylinder liquid fuel to the observed increase of HC emissions was as much as 96%.

Total and speciated, engine-out, hydrocarbon (HC) emissions have been measured as a function of time after a 23°C cold start of a gasoline-fueled, V-8 engine. Hydrocarbon emissions from two fuel injection systems were compared: a production port-fuel-injection (PFI) system; and a pre-vaporized (heated) central-fuel-injection (PV-CFI) system. The results indicate that, for this particular engine at the chosen operating conditions, the effect of fuel preparation on HC emissions during cold start is minimal at low load (2.57 bar IMEP (gross), MAP = 0.34 bar) but becomes significant at higher load (5.15 bar IMEP, MAP = 0.58 bar) early in the cold start. Comparison of the relative contribution to the exhaust HC of a series of fuel-derived alkanes suggests that fuel absorption in oil films is a minor contributor to HC emissions from this engine during a 23°C cold start.

The reduction of emission levels for low (LEV) and ultra low (ULEV) emissions vehicles requires catalyst with rapid thermal response for quick light-off while providing stable high temperature performance under highway driving conditions. The design of substrates which carry the three-way catalyst formulations are key to meeting the complex dual performance requirements. Enhanced mass transfer and reduced thermal mass can be accomplished while maintaining acceptable back pressure. The design principles and selection of substrate properties are described as is their effect on the emissions from the Federal Test Procedure. Transient driving performance simulations allow for selection of optimum advanced substrate designs.

In this paper the effect of in-cylinder crevices formed by the piston cylinder clearance, above the first ring, and the spark plug cavity, on the entrapment of unburned fuel air mixture during the late compression, expansion and exhaust phases of a spark ignition engine cycle, have been simulated using the Computational Fluid Dynamic (CFD) code KIVA II. Two methods of fuelling the engine have been considered, the first involving the carburetion of a homogeneous fuel air mixture, and the second an attempt to simulate the effects of manifold injection of fuel droplets into the cylinder. The simulation is operative over the whole four stroke engine cycle, and shows the efflux of trapped hydrocarbon from crevices during the late expansion and exhaust phases of the engine cycle.

A sampling system was developed to measure the evolution of the speciated hydrocarbon emissions from a single-cylinder SI engine in a simulated starting and warm-up procedure. A sequence of exhaust samples was drawn and stored for gas chromatograph analysis. The individual sampling aperture was set at 0.13 s which corresponds to ∼ 1 cycle at 900 rpm. The positions of the apertures (in time) were controlled by a computer and were spaced appropriately to capture the warm-up process. The time resolution was of the order of 1 to 2 cycles (at 900 rpm). Results for four different fuels are reported: n-pentane/iso-octane mixture at volume ratio of 20/80 to study the effect of a light fuel component in the mixture; n-decane/iso-octane mixture at 10/90 to study the effect of a heavy fuel component in the mixture; m-xylene and iso-octane at 25/75 to study the effect of an aromatics in the mixture; and a calibration gasoline.

An engine-based test has been developed to measure the oxygen storage capacity of a catalyst. The test utilizes the difference in the engine-out and tailpipe A/F ratios following rich-to-lean and lean-to-rich A/F transitions in order to quantify the storage or release of oxygen. The technique also results in the determination of the water-gas shift constant for the tailpipe exhaust. The technique was used to measure the oxygen storage capacity of a fresh catalytic converter at inlet temperatures of 400, 500, and 600°C for catalyst volumes of 1.5L and 2.8L. The procedure was repeated after the converter had been aged at an inlet temperature of 800°C for 20, 40, and 60 hours. The oxygen storage capacities are related to the emissions performance of the converter on A/F ratio sweep tests. For the fresh converter, the calculated oxygen storage capacity increased with temperature.

The effects of catalyst and fuel formulation changes were investigated on vehicles meeting European Stage II (94/12/EC) emission limits when tested over the modified European test cycle. The OEM standard Pt/Rh catalyst formulation was compared with advanced Pd/Rh catalysts, at nominally the same PGM cost, and with Pd/Rh catalysts at increased PGM loadings. No other changes were made to the vehicles. The largest relative emissions benefits for the advanced Pd/Rh catalysts at equivalent PGM cost were 28% for THC, 30% for CO and 22% for NOx. Pd/Rh catalysts with higher PGM loadings gave further improvements in emissions, with total reductions of 38% for THC, 40% for CO and 31% for NOx compared to the standard OEM catalyst. In addition, one of the vehicles was tested with a Pt/Pd/Rh catalyst formulation. The performance of this catalyst was comparable with the Pd/Rh catalyst at similar PGM loading.

The effects of fuel formulation changes on vehicles meeting European Stage 1 (91/441/EEC) and Stage II (94/12/EC) emission limits have been investigated. Vehicles in the Euro Stage II fleet were advanced specification versions of the vehicle models in the Euro Stage I fleet. However, the basic engine blocks and capacity were the same. The observed improvements in emissions were attributed to changes, such as position of the catalyst and lambda sensor, improved fuel delivery systems, and to improvements in engine control strategy. These engine modifications resulted in reduced catalyst light-off times and improved AFR control. Emissions improvements, over the modified European test cycle, as a result of these changes were approximately 50% for CO and NOx and 30% for THC. A fuel matrix was designed in order to study the effect of six fuel parameters on exhaust emissions from the two levels of vehicle technology.

The aerospace industry has entered a new level of World Class Manufacturing, in which manufacturing functions require fixturing to be just as flexible as the machine tool doing the operation. Flexible tooling has opened new doors for the aerospace industry by creating new tools which are automatically reconfigurable and totally reusable on future programs. Benefits include decreases in non-recurring costs, (such as in the area of tool design and fabrication) and recurring costs, (such as in the area of tool setup / removal and storage).

Coldworking holes is an established manufacturing procedure in the aerospace industry. There are two coldworking methods used today: split-sleeve and split-mandrel. The intricate steps of these processes are not completely understood. There has been no investigation into the differences in the mechanisms of the two processes. Initial results from an ongoing program reveal that the differences in the mechanisms impart the split-mandrel process with advantages over the split-sleeve process, including the ability to coldwork 7000 series aluminum without shear cracking at the axial ridge, and the ability to effectively automate the process.

Three European gasoline vehicles, homologated to European Stage II limits, and two US gasoline vehicles, certified to Californian TLEV limits, were evaluated over the new European test cycle for year 2000 standards and the US Federal Test Procedure. Three advanced catalyst technologies were tested on these vehicles, in the original equipment converter position in all but one case, without any additions or changes to the existing emission control system. Prior to testing they were aged on a cycle representing 80,000 km road durability. Up to 30% reductions in emissions were achieved from those for which the vehicles were homologated, at an incremental cost in precious metal of 12 - 23 US$ per liter of catalyst compared to the original converter precious metal value (precious metal prices of 16 July 1996).