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Traction machines have been frequently used to study the rheological properties of lubricants in elasto-hydrodynamic lubrication (EHL) contacts. Fundamental properties are inferred from EHL traction measurements based on the average pressures and temperatures in the contact. This average approach leads to uncertainty in the accuracy of the results due to the highly nonlinear response of fluid rheological behavior to both pressure and temperature. A non-averaging method is developed in this paper to determine the elastic and plastic properties of traction fluids operating in EHL contacts at small slide-to-roll ratios. A precision line-contact traction rig is used to measure the EHL traction at a given oil temperature and Hertz pressure. By choosing a sensible pressure-property expression, the parameters of the expression can be determined through the initial slope and peak traction coefficient of the traction measurements.

This paper presents a unique line-contact EHL test rig. One of the features of the rig is that the EHL junction is formed by a cylindrical roller in contact with the internal surface of a cylindrical ring. With this design configuration, only a very small amount of lubricant is needed even for high speed testing as the centrifugal force maintains a good oil supply to the contact region. The roller and the ring are driven separately by servomotors. The roller assembly is mounted on a platform supported by a hydrostatic air bearing to allow accurate traction measurement. With a coated sapphire ring, the EHL film thickness in the contact zone can be measured by means of optical interferometry. The control and data acquisition systems are integrated in a Labview environment, and the test sequence can be programmed and automatically carried out by the control program. The innovative design features and test parameters of the rig are presented along with a set of typical test results.

Thermal barrier coatings have been shown to be effective at reducing particulate emissions from diesel engines. Prior work by the authors has demonstrated a significant decrease in particulate emissions from a thermal barrier coated, single-cylinder, indirect injection (IDI) diesel engine, primarily through reduction of the volatile (VOF) and soluble (SOF) fraction of the particulate. Most of this prior work relied on conventional, commercially available, petroleum-based lubricants. Recently, the authors demonstrated additional particulate emissions reductions when a high oleic sunflower-based lubricant was used instead of a conventional petroleum-based lubricant. This paper concerns the manner in which the particulate was reduced, and reports on the changes in particulate composition and morphology between the two lubricants. Composition was examined quantitatively through thermal analysis of the particulate from a single-cylinder IDI diesel engine.

Flame kernel growth and cylinder pressure data were simultaneously obtained from an optically-accessible, square piston, SI engine. Flame kernel growth was measured using simultaneous, orthogonal, Schlieren photography, while cylinder pressure was measured using a piezoelectric pressure transducer. The data were analyzed on a cycle-resolved basis to determine the correlation between cyclic fluctuations in flame kernel growth and cylinder pressure. The engine was operated at 875 RPM with premixed, prevaporized, stoichiometric isooctane in air. The engine, designed with ported intake and exhaust, was fired every tenth cycle to ensure complete scavenging. Tests were conducted with and without nitrogen dilution, while ignition timing was fixed at 25° BTDC. With 0% dilution the percent variation in the maximum cylinder pressure was 8.5%, while with 10% dilution the percent variation increased to 14%.

The effects of intake-generated swirl and tumble on cold start performance have been investigated in a firing single-cylinder Gasoline Direct-Injection (GDI) engine. The engine utilizes a Ford Zetec cylinder head modified for GDI operation and a fused silica cylinder which provides extensive optical access to the combustion chamber. Uniquely designed port-inserts were positioned in the intake ports to generate enhanced swirling or tumbling motion inside the cylinder. Experiments were conducted using a constant speed (∼ 900 rpm) simulated cold start procedure, where the engine is motored for approximately 40 cycles, after which fuel injection and spark ignition commence and continue for 190 cycles and then the engine is stopped. Measurements were made of the various engine temperatures, engine-out total hydrocarbon emissions, and in-cylinder pressure throughout the test period.

Several oxygenates have been proposed and tested for use with or as diesel fuel. This paper examines two such oxygenates, CETANER™ and dimethyl ether (DME), partially or wholly produced by Air Products and Chemicals, Inc's Liquid Phase Technology. In previous studies on a single cylinder compression ignition engine and a Volkswagen TDI four cylinder engine, significant reductions in particulate matter emissions were observed with blends of CETANER™ in diesel fuel. In this study, experiments were performed on a multi-cylinder Navistar 7.3L Turbodiesel engine confirmed and extended the observations from the earlier studies. This is an important step in not only showing that the fuel does perform on each type of engine in similar fashion, but also in showing that DME and its derivatives can give consistent, significant results in lowering emissions. The oxygenated fuels were blended to achieve a net addition of 2 wt.% oxygen in the blended fuel.

Sequential four-ball wear tests have been used to evaluate automotive crankcase oils for use as heavy-duty hydraulic fluids and automotive crankcase lubricants. This test technique has been adapted for use with steel-on-steel, steel-on-ceramic and ceramic-on-ceramic bearing systems. In addition to the conventional “run in” and “steady-state” wear studies, the data produced have been used to interpret bearing unit load levels for the various bearing systems involved. The data produced show that in many cases hybrid bearing systems (steel-on-ceramic) and ceramic-on-ceramic bearing systems may be useful at higher unit loadings than the conventional steel-on-steel systems. These studies focused on achieving low boundary lubricated wear rates. The bearing unit loadings were obtained from the unit bearing pressures after the “run in” of the specific bearing system.

The objective of this research was to characterize the effects of fuel component volatility on gasoline direct injection (GDI) engine cold start. Three different fuel components, representing gasoline light end, mid-point and heavy end components, were used to form three fuel blends of different volatility. Performance tests and in-cylinder fuel distribution imaging tests using these fuel blends were carried out in a firing single-cylinder optically-accessible engine following a simulated cold start test schedule. Performance results, based on in-cylinder pressure and engine-out hydrocarbon measurements, during the initial transient phase of GDI cold start showed significantly degraded performance with the low volatility fuel blend, while the high volatility blend showed slightly improved performance. Neither the low nor high volatility fuel, however, showed a discernable effect on the quasi-steady state cold start performance.

The majority of crankcase lubricants are now formulated to contain polymeric additives to improve the viscosity temperature properties to provide a better lubricating film in the various bearing systems in an internal combustion engine. These VI (viscosity index) improved lubricants are non-Newtonian under the high shear conditions that exist in most automotive bearing systems. The conditions of interest range from starting the engine at temperatures of as low as -40°C to operating the engine at normal operating conditions including bearing temperatures of 150°C or higher. This paper presents a method for predicting the viscosity shear relationship for a series of SAE multigrade engine oils as a function of temperature and shear stress. The method is demonstrated using three types of polymeric VI improvers currently used in SAE multigrade engine oils. The polymer types include olefin copolymers (OCP), polymethacrylates (PMA), and styrene-isoprene copolymers (SI).

This paper summarizes an investigation of the changes in combustion and particulate emissions caused by thermal barrier coatings placed in the combustion chamber of a diesel engine. The engine was a Yanmar TS 180 single cylinder diesel utility engine with a continuous rating of 15 HP (11.2 kw) @2400 RPM. The test protocol was the International Standards Organization (ISO) 8178 Standard Type-E3 test which simulates a marine diesel engine. Total particular matter emissions were measured by collection on Pallflex, filters via fractional sampling using a Sierra Instruments BG-1 Micro-Dilution Test Stand. The engine was operated with and without the thermal barrier coatings. The coated parts are the piston crown, the cylinder head (fire deck), and the valves. Scanning electron micrography (SEM) provided analysis of particulate size, microscopic structure and elemental composition of the particulate samples.