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Viewing 121 to 150 of 58645
1989-09-01
Technical Paper
892103
G. E. Andrews, J. R. Harris, A. Ounzain
A Ford Valencia engine was tested with a sudden start-up to a fixed speed and load and the coolant, lubricating oil and exhaust emissions were monitored as a function of time. Steady state tests were carried out with and without air preheat and with synthetic lubricating oil. These showed that the air preheat had a major impact on the hydrocarbon emissions and this had to be eliminated if the influence of the lubricating oil and water warm-up alone was to be investigated. The synthetic lubricating oil tests showed the importance of the lubricating oil in the hydrocarbon emissions as well as the reduced sfc. Tests with water and lubricating oil initially at ambient temperatures were compared with tests with the water externally heated and the lubricating oil cold, and with cold water and hot lubricating oil.
1989-09-01
Technical Paper
892097
K. H. Luo, H. Daneshyar
The three velocity components and turbulence intensity were measured at the valve curtains around the two inlet valves of a four-valve s.i. engine with a pent-roof chamber. The measurements were made using hotwire anemometry in a steady-flow rig. Data were collected over a wide range of valve lifts and flow rates. The results show that the velocity profiles are strongly dependent on the valve lift and the surrounding geometry but almost insensitive to the flow rate. Flow separations are identified at certain azimuthal locations for large valve lifts. The turbulence intensity varies around the valve peripheries and across the valve gaps, as do the exit angles of the issuing flows. Their profiles are affected by flow separations from the valve seats and faces and by flow interferences between the two inlet valves. These detailed profiles can be used as boundary for multi-dimensional in-cylinder flow models.
1989-09-01
Technical Paper
892098
Thierry A. Baritaud
Transient flame propagation, gas velocities and heat release are measured in a spark-ignited engine with optical access using high speed shadowgraph visualization, laser velocimetry and pressure trace analysis. For a set of running conditions varied around a reference case, ensemble-averaged and cycle-resolved flame front evolutions, velocity fields and heat release are presented for lean mixtures of propane and air. The changed parameters include flow-field (swirl, tumble), rpm (600 and 1200), equivalence ratio (0.7 and 0.9), volumetric efficiency (0.5 and 0.9) and spark-timing. Given the usable field of view, the combustion can be observed during 50% of its total duration which corresponds to a 15% burnt fraction. An analysis of the data shows that the flame expansion velocities are highly transient during the observable combustion phase. An acceleration yields to a 2 to 4 fold velocity increase. The flame velocities depend strongly on the operating conditions.
1989-09-01
Technical Paper
892102
Thomas Heinze, Thomas Schmidt
Quantitative, ensemble averaged, two dimensional maps of the fuel-air ratio in an injection jet were obtained through a series of single point Raman measurements. Pure n-heptane was injected with a commercial injection system into a special high pressure (45 bar) and high temperature (500 °C) observation chamber. The investigations were performed between injection and autoignition of the spray, and between 15 mm and 48 mm below the nozzle. On the basis of nearly 100,000 single point measurements a computer film was produced showing that faster propagating fuel in the inner spray and at the spray tip plays an important role in mixture formation.
1989-09-01
Technical Paper
892104
Takashi Noda, Masago Yamamoto, Yasuhiro Ohmiya, Jun'ichi Kawamoto, Masahiko Nakada
Oil consumption mechanism was analyzed by measuring the radial movement of the upper side rail in a three piece type oil ring, together with the piston movement. Ultra-miniature inductive displacement sensors were designed to measure the oil ring movement and fitted on the upper side rail with a part of the 3rd land cut out. The clearance between the side rail and the cylinder wall was measured under various operating conditions. The results showed that the radial movement of the oil ring was affected by the piston movement, which results in the possibility of degrading the oil control ability for the cylinder wall because the oil ring temporarily moves with the piston. Accordingly, the designs to improve the piston movement or to be less affected by the movement proved to be an important factor for the reduction of the oil consumption.
1989-09-01
Technical Paper
892100
M. Parsl, H. Daneshyar
Measurements of the magnitude of the instantaneous velocity components were taken within the combustion chamber of a four-valve head using a triaxial hot-wire probe. Cyclic variation in the “mean” flow was studied for operation with only the large inlet valve. Several groups of “similar” cycles having a time-averaged mean velocity within a specified range were obtained. The mean and rms velocities were estimated for each group using an ensemble averaging technique. The overall “corrected” turbulence intensity and the overall power spectral density function were also determined. The overall power spectra for different engine speeds were normalized by the engine speed and the overall “corrected” turbulence intensity. Large cyclic variations in the levels of mean velocity and turbulence intensity were clearly demonstrated by the results. The turbulence intensity was found to be overestimated significantly by the ensemble analysis due to cyclic variations in the mean velocity.
1989-09-01
Technical Paper
892109
M. F. Salomon, M. Galic, R. N. Jones, R. W. Dix, J. V. Stoffa, B. D. Domonkos, M. J. Covitch
The Sequence IID engine test procedure, traditionally used to evaluate the anti-rust performance of lubricants, has also been used to measure emulsion forming tendencies of lubricants. In the IID engine, emulsion collects at the base of the crankcase ventilation breather tube condenser which causes partial plugging and an increase in crankcase pressure. The purpose of this paper is to describe the chemical nature of the emulsion and to elucidate physical factors which have been found to influence emulsion buildup on the lower face of the Sequence IID condenser. The process of emulsion formation was observed in real time using a fiber optic video camera which aided in understanding the influences of condenser face roughness and lubricant chemistry on crankcase pressure. The effect of substituting unleaded fuel for standard Sequence l!D leaded fuel was also determined.
1989-09-01
Technical Paper
892107
Kimitaka Saito, Toshihiko Igashira, Masahiko Nakada
The reduction of engine oil consumption rate is one of the important concerns for automotive engineers. However, it has been difficult to solve this subject, since the oil consumption mechanism has not yet been elucidated. In this study, to clarify the oil loss mechanism via the piston rings, a transparent glass cylinder engine was used to observe oil behavior between cylinder wall and piston surface. For photographic observation, a high speed camera, a still camera. and a TV camera were used. Since the new photographic system by using TV camera with a synchro - flash and a synchro-memory was applied, it was also possible to observe the oil behavior in detail. Moreover, a new visual method by which colored oil was injected from the various points on the piston surface and traced was developed for easy analysis of oil movement around the piston ring.
1989-09-01
Technical Paper
892112
J. A. McGeehan, E. S. Yamaguchi
We were able to identify engine blow-by as a primary factor affecting camshaft wear in gasoline engines. Using a 2.3-liter overhead-camshaft engine, we isolated the valve-train oil from the crankcase oil and its blow-by using a separated oil sump. We find that: with engine blow-by, the camshaft wear was high. without blow-by, the camshaft wear was low. with blow-by piped into the isolated camshaft sump, the wear was high again. Later studies identified nitric acid as a primary cause of camshaft wear. It is derived from nitrogen oxides reacting with water in the blow-by. But even in the presence of blow-by, camshaft wear can be controlled by the proper selection of zinc dithiophosphates (ZnDTP) and detergent type.
1989-09-01
Technical Paper
892114
Yoshinori Yamaguchi, Masahiko Takesue, Takeshi Maruya, Takashi Nagashima
In this work, the connecting rod bearing seizures as one of the problems latent to the high-output, high-speed engines are investigated. Studies are conducted on the evaluation of anti-seizure properties of a single connecting rod bearing installed in the test rig as well as in commercial engines. As the results of the former study, the bearing wear is affected by the rod surface roughness (Rmax ) and the oil temperature (viscosity). Further, frequent metal to metal contacts of bearings are observed by the electrical measuring apparatus under higher temperature, and full load conditions. While in the latter, it is found the total heat generated of the bearing is the important factor affective to the bearing seizures, and can be analyzed by using PV value, rod surface roughness and oil viscosity.
1989-09-01
Technical Paper
892110
Takashi Inoue, Yorishige Maeda, Masashi Takeda, Masahiko Nakada
The oil consumption phenomena during transient engine operating condition is analyzed. The investigation of the oil consumption by means of the real-time oil consumption meter shows that higher intake manifold vacuum during engine-brake condition causes a larger amount of transient oil consumption. The reverse blowby gas flow into the combustion chamber from the crankcase is generated by the high vacuum under engine-brake condition. It is found that this reverse gas flow carries the oil into the chamber from the third land of the piston through the ring end gap of the compression rings. The oil on the piston skirt leaks into the third land through the clearance between the oil ring and the cylinder bore. The weakened bore-to-ring contact pressure by the piston slap motion increases the amount of the leakage oil. New ring sets and pistons are developed based on the results of this study.
1989-09-01
Technical Paper
892116
Charles B. Richardson, Donald A. Gyorog, Loren K. Beard
A Pore Fuel Injector Deposit (PFID) test has been developed which provides repeatable results. The test can discriminate gasolines with differing fuel injector fouling tendencies in vehicles. Results confirm previous work that added mono-and diolefins increase deposit growth. The test is also able to evaluate the performance of additives. Other factors found to affect injector deposit formation include: injector soak temperature, injector soak pressure, weeping vs non-weeping injectors, and the presence of oxygen around the injector pintle. The PFID test can be run in about one quarter the time needed to evaluate fuels in vehicle and dynamometer tests.(1)
1989-09-01
Technical Paper
892115
Thomas J. Bond, Frank S. Gerry, Richard W. Wagner
With increased attention now being focused on controlling fuel-related intake system deposits, the need for high-performance gasolines has intensified. Certain import and domestic automobile manufacturers have expressed concern that some of today's gasolines formulated to prevent fuel injector deposits may have a negative effect on deposit control in other areas of the fuel intake system. This paper covers the development of a laboratory engine test procedure to evaluate the impact of fuel additive technology on intake valve deposits. Additive formulation has been optimized providing outstanding control of intake valve deposits with no compromise in PFI deposit control.
1989-09-01
Technical Paper
892119
Sheldon Herbstman, Kashmir Virk
A variety of diesel fuels were investigated to develop an injector test to evaluate detergent activity. In this test a 6.2 liter GM engine with indirect injector capabilities was run for either 15 or 50 hr. The injectors were then rated by air flow for plugging. Our results indicated variability due to differences in fuels. A high mercaptan content fuel increased injector plugging. On the other hand, blends of base fuel with 30 or 50% Light Cycle Gas oil (LCGO) had no effect upon injector plugging even though total aromatics, including polyaromatics, and total sulfur contents, primarily thiophenes, increased. A low sulfur content California fuel decreased injector plugging. The results suggested that mercaptans increase injector deposits while thiophenes do not. Some work was also done using two commercially available detergents. Both were effective in reducing injector plugging at proper concentrations (keep clean). Cleanup capability was noted for one of these additives.
1989-09-01
Technical Paper
892134
G. E. Hundleby
Natural gas is one of the alternative fuels to diesel being considered for low emissions heavy-duty applications. The favoured operating strategies for low emissions SI gas engines are identified as those with high levels of dilution - stoichiometric operation with EGR, and lean-burn. A well-matched exhaust catalyst is needed to produce the lowest emissions levels. Increasing the accuracy of transient air-fuel ratio control is shown to improve the emissions still further. The most favourable combinations of engine operating strategy and control accuracy are identified with respect to fuel economy and first cost. The Co-Nordic Natural Gas Bus Project is an example of an engine development programme aimed at achieving the lowest possible exhaust emissions levels, and as such uses the lowest emissions approach of a stoichiometric engine strategy with EGR and high accuracy control.
1989-09-01
Technical Paper
892123
David L. Harrington, Russell F. Stebar, Frank Caracciolo
The process of deposit-induced, fuel-flow reduction in multiport fuel injectors of the director-plate type was investigated both experimentally and analytically in order to understand both the flow-reduction mechanism and the non-linear variation in flow reduction with engine operating time. Injectors that had accumulated deposits in previous extended engine testing utilizing a rapid-plugging fuel were flow-tested, and the orifice plates from two of the injectors containing deposits were examined using a scanning electron microscope. A thin, carbonaceous deposit protruding into the flow paths of the orifices was found to be present on the downstream face of the orifice plate, but not present within the fuel orifices or on the upstream surface of the plate. Based upon these observations, calculations were made using a fluid flow model of an orifice plate with deposits.
1989-09-01
Technical Paper
892136
R. R. Raine, J. S. McFeaters, S. T. Eider, J. Stephenson
The use of compressed natural gas (CNG) as a fuel for heavy transport engines is still in the development stage, however, experience has shown promising results in certain applications. While most of the recent work done in New Zealand on CNG use has been centered around non-turbocharged, high speed, spark ignition (SI) conversions, there is still likely to be a role for dual fuel engines in some applications. This paper presents a review of New Zealand experiences with the use of CNG as a fuel in heavy transport diesel engines. Both dual fuel and 100% CNG fuelling (dedicated spark ignition conversions) are discussed. The advantages and disadvantages of each are reviewed in terms of vehicle performance, fuel costs and operational experiences. Brief reviews of experimental results and discussions of technical aspects of conversions, experience in fleet use, economic and operational aspects, current research and computer modelling of fleet performance are also included.
1989-09-01
Technical Paper
892133
Christopher S. Weaver
Natural gas has considerable potential as a “clean” fuel for motor vehicles. This paper reviews the present state of the art in natural gas vehicles, focusing on engine technology and emissions. Natural gas engines generally show very low emissions of reactive hydrocarbons, carbon monoxide, and particulate matter, but NOx emissions can be fairly high. Approaches to NOx control include stoichiometric operation using a three-way catalyst and air-fuel ratio feedback, and “lean-burn/fast-burn” engines with NOx controlled through reduced flame temperature. Engines of both types have demonstrated excellent emissions performance - exceeding U.S. 1994 emissions requirements for heavy-duty engines. Optimized natural gas engines are significantly more efficient than present gasoline engines, with lean-burn natural gas engines approaching diesel efficiency.
1989-09-01
Technical Paper
892131
Norman R. Sefer, Jimell Erwin
A contemporary coal liquefaction product from the Wilsonville pilot plant was processed to make two diesel test fuels for engine research. A naphtha fraction was separated by distillation, and the diesel fraction was upgraded by hydrogenation. Processing objective was to make two stable products with acceptable ignition quality. A trial run was made over a range of pressures and residence times to establish minimum severity to meet the objective. About 85 gallons of product was made at minimum severity and 81 gallons at slightly higher severity. The products resembled petroleum diesel fuels except for marginally high viscosity and low accelerated stability. Product characterizations included 30.1 and 35.4 cetane number.
1989-09-01
Technical Paper
892060
Akio Yasuda, Yukihiro Tsukasaki, sumio Ito, Hidetaka Nohiro, Tokuta inona
The second generation methanol lean burn system has been developed. The power unit is a new, 4 valve 1.6L in-line four with compact combustion chambers. Lean misfire limit was extended by using a swirl control valve in the intake port which improves combustion under partial load. Lean mixture control is made by using a signal from lean mixture sensor provided in the exhaust manifold. An EGR system has been newly adopted to reduce NOx emissions and a under-floor type catalyst is also used to reduce formaldehyde emission in the cold transient mode in addition to the manifold type catalyst. Permissible excess air ratio range (PEXARR) was defined and used to indicate the potential for reducing vehicle NOx emissions in engine dynamometer tests to optimize compression ratio, valve timing and swirl ratio and to evaluate the effect of the EGR.
1989-09-01
Technical Paper
892058
Richard M. Frank, John B. Heywood
An experimental study was conducted on a direct-injection stratified-charge (DISC) engine incorporating a combustion process similar to the Texaco Controlled Combustion System and operated with gasoline. Analysis of the injected fuel flow and the heat release showed that the combustion process was characterized by three distinct phases: fuel injection and distribution around the piston bowl, flame propagation through the stratified fuel-air mixture, and mixing-controlled burn-out with the heat-release rate proportional to the amount of unburned fuel in the combustion chamber. This characterization was consistent with previous visualization studies conducted on rapid-compression machines with similar configurations. Experiments with varied injection timing, spark plug location, and spark timing showed that the combustion timing relative to injection was critical to the hydrocarbon emissions from the engine.
1989-09-01
Technical Paper
892064
Charles M. Urban, Thomas J. Timbario, Richard L Bechtold
A study was conducted to determine the feasibility, performance, and emissions of a Detroit Diesel Corporation 8V-71 transit bus engine using ignition-improved methanol as fuel. Major objectives to be achieved by the study were: 1) to determine the minimum amount of ignition improver required for acceptable engine operation; and 2) to compare the exhaust emissions with ignition-improver methanol to emissions with diesel fuel. The engine was tested for emissions using the transient and 13-mode emission procedures and for smoke using the Federal smoke test. In addition to measurement of regulated emissions and smoke, cylinder pressure traces were obtained and compared with pressure traces from operation on diesel fuel. Minimum modifications were made to the engine in adapting it for operation on the methanol/additive mixture.
1989-09-01
Technical Paper
892065
Margaret K. Singh
This paper presents results of an assessment that identifies vehicle technology and fuel distribution system changes and costs associated with providing sufficient alternative fuels to displace one million barrels/day petroleum in the transportation sector in the 1995-2005 timeframe. The paper concludes that the capital cost of developing fuel delivery systems and a sufficient number of vehicles to achieve this displacement will be $22 billion if the alternative fuel is methanol, $36 billion if natural gas, and $288 billion if electricity. The predominant component of these costs is that of the incremental cost of the vehicles.
1989-09-01
Technical Paper
892068
R. H. Thring
Homogeneous Charge Compression Ignition (HCCI) combustion can be made to occur in a four-stroke engine with smooth and even combustion under some circumstances. It offers the possibility of light load operation without throttling, thus giving fuel economy like a diesel, in the same engine allowing full load operation with homogeneous charge, thus giving a power density comparable to a gasoline engine. This paper gives results of an experimental program in which the ranges of permissible values of the operating parameters were defined for HCCI operation of a four-stroke engine. It was found that HCCI required high exhaust gas recirculation (EGR) rates (in the range of 13 to 33 percent) and high intake temperatures (greater than 370°C). Under the right conditions HCCI combustion produced fuel economy results comparable with a D.I. diesel engine (ISFC in the range 180 to 200 g/kWh).
1989-09-01
Technical Paper
892072
Terry L. Ullman
Increasingly stringent emission requirements for heavy-duty diesel engines stresses the importance of both engine design and diesel fuel quality. The Coordinating Research Council sponsored this test work to yield quantitative emission data and emission models to relate diesel fuel properties to emissions from modern heavy-duty diesel engines. Regulated and selected unregulated emissions from three engines were measured over the EPA transient test procedure using several fuels having controlled variation in three primary fuel properties: aromatics, volatility (as the 90 percent boiling point temperature), and sulfur. Models for transient composite emissions were obtained using multiple linear regression techniques, and changes to regulated emissions for selected changes in fuel properties were estimated from the models. Of the three primary fuel variables, aromatic content and volatility were significant for emissions of HC, CO, and NOx.
1989-09-01
Technical Paper
892073
Ömer L. Gülder Boris Glavinčevski, Norman N. Kallio
Our previous methodology of predicting the cetane number of middle distillates and heavy marine diesel fuels from hydrogen type distribution determined by proton NMR has been extended to cover the olefinic hydrocarbon structures and pure hydrocarbon compounds. Although, an ability to predict cetane numbers of olefinic fuels and pure hydrocarbons is not of immediate practical importance, from a more fundamental point of view, such a capability may lead to a better understanding of the ignition/fuel structure relationship in diesel engine combustion. The proposed technique is capable of predicting the ignition quality of almost all types of petroleum liquids including pure hydrocarbons.
1989-09-01
Technical Paper
892080
Paul T. Williams, Yanjin Shen, Gordon E. Andrews, Keith D. Bartle
Lubricating oil taken from the sump of a direct injection diesel engine has been analysed for the concentration of hydrocarbon contamination over a period of time. The oil was filtered and the sediment SOF analysed together with the filtrate. The results showed that there was an increase in the contamination in the used oil for both the filtrate and sediment hydrocarbon contamination. The carbon number distribution of the filtrate and sediment SOF were different. The filtrate representing contamination of the oil by fuel dilution and the sediment SOF contamination by particulates adsorbed into the oil in the combustion chamber. The highest contribution to the hydrocarbon contamination of the oil was from the filtrate in the early ageing period with an increasing contribution from the SOF of the sediment.
1989-09-01
Technical Paper
892083
Yongseo Ko, Richard W. Anderson
Heat transfer from the flame kernel to the electrodes during the spark ignition process is of interest for predicting the minimum ignition energy at a given engine operating condition. Experiments conducted in a constant volume bomb at near ignition limit conditions with small and large electrode surface areas (comparable to J gap plug), coupled with a phenomenological model, show the lumped heat transfer coefficient to range from 150-200 W/m2 K during the first 3 milliseconds of the ignition period. An additional analytical approach that uses the measured time dependent kernel-electrode contact areas gives reasonable agreement with the experimentally determined heat transfer coefficient and demonstrates that the dominant mechanism is thermal conduction. Heat loss from the flame kernel is comparable to the net ignition energy for the small electrodes after 3 milliseconds while that for the large electrodes is shown to equal the net ignition energy within 800 microseconds.
1989-09-01
Technical Paper
892085
Rolf D. Reltz, Tang-wel Kuo
Multi-dimensional computations were made to assess the effect of crevice flows through piston-cylinder-ring crevices on combustion and engine-out hydrocarbon emissions. The computations were made using the KIVA code with a characteristic time combustion sub model that accounts for laminar kinetics and turbulent-mixing effects. The crevice-flow boundary conditions were specified using a phenomenological crevice-flow model. A central-ignition pancake-chamber engine was considered, and the effects of top-land crevice design and engine operating condition were examined. The computed peak cylinder pressure was found to be 6 to 8 percent lower in cases with crevice flow than without because the crevice flow reduced the effective in-cylinder charge mass by similar percentages during the main stages of combustion. However, the details of combustion were essentially unchanged by the crevice flow.
1989-09-01
Technical Paper
892084
Deana D. Brehob
In many operating regimes, exhaust gas recirculation (EGR) while maintaining MBT spark timing improves cycle efficiency in SI engines. As the level of exhaust dilution is increased, the flame speed is reduced and the combustion rate is impaired. This leads to a drop in fuel economy as EGR rates are increased beyond the optimal level. To take advantage of the efficiency benefit of EGR without incurring the penalties of late combustion, a sensor which detects late combustion is tested. The signal from an ionization sensor placed near the exhaust port has been found to correlate to combustion which continues late into the expansion stroke. It may be possible to use the output from the ion sensor to maintain the EGR at the the optimum for fuel economy.
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