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Technical Paper

Effect of Fuel Atomization at a Fuel Supply System on the Lean Burn Characteristics in a Spark-Ignition Engine

1991-02-01
910568
This paper presents the fuel atomization effect of a fuel supply system on the lean burn characteristics of a spark-ignition engine and its mechanism. The fuel supply system can realize extremely different two state of atomization, i.e., wall-film of fuel flow and ultra-fine spray (less than 7 um S.M.D. by Malvern measurement). For the first step of the study, the atomization effect is examined under steady operation; several operating parameters including cyclic variability are expressed against the A/F over the wide range of operating condition. Within the operation limits, the fuel atomization does not affect any parameters, while it gives pretty much influence on the lean operation limit. Furthermore, this influencing behavior strongly depends on the throttle valve position and its opening.
Technical Paper

The 1990 SAE Methanol Challenge: Summary of a Successful Student Design Competition

1991-02-01
910570
A follow-up to the 1989 Society of Automotive Engineers (SAE) Methanol Marathon called the Methanol Challenge was held in April 1990. One of a series of engineering student competitions using alternative fuels organized and conducted by the Center for Transportation Research at Argonne National Laboratory, the Methanol Challenge pushed the technology for dedicated M85 (85% methanol, 15% hydrocarbon fuel) methanol passenger cars to new levels. The event included complete federal exhaust emissions, cold-start and driveability, performance, and fuel economy testing. Twelve teams of student engineers from the United States and Canada competed in the Challenge using Chevrolet Corsicas donated by General Motors (GM) to the schools. The winning car, from the University of Tennessee, simultaneously demonstrated extremely low emissions, dramatically increased performance, and significantly improved fuel economy.
Technical Paper

Engine Knock Characteristics at the Audible Level

1991-02-01
910567
The effects of combustion chamber and intake valve deposit build-up on the knocking characteristics of a spark ignition engine were studied. A Chrysler 2.2 liter engine was run continuously for 180 hours to build up intake valve and combustion chamber deposits. In the tests reported here, the gasoline used contained a deposit controlling fuel additive. The engines's octane requirement increased by 10 research octane numbers during this extended engine operating period. At approximately 24 hour intervals during these tests, the engine was audibly knock rated to determine its octane requirement. Cylinder pressure data was collected during knocking conditions to investigate the knocking characteristics of each cylinder, and deposit build-up effects on those statistics. Cylinder-to-cylinder variations in knock statistics were studied. Analysis of the data indicated that some 20 to 40 percent of cycles knock before the knock is audibly detected.
Technical Paper

The Effects of Speed and Manifold Pressure on Autoignition in a Motored Engine

1991-02-01
910566
This paper presents a comparison of the autoignition tendencies for straight chain hydrocarbons and mixtures of primary reference fuels in a motored engine. Minimum initial gas temperatures required to produce autoignition were measured as a function of fuel type, engine speed, and inlet manifold pressure. In-cylinder gas pressure vs. crank angle and exhaust gas carbon monoxide concentrations were also monitored during these experiments as indicators of chemical activity. Overall, the autoignition behavior of n-pentane, n-hexane, and their equivalent octane number primary reference fuel blends was found to be dissimilar in (i) the inlet temperatures at which autoignition occurred; (ii) the amount of CO formed prior to autoignition; and (iii) the effect of engine speed on minimum inlet autoignition temperatures. Possible causes for this behavior are discussed in the paper in terms of the Negative Temperature Coefficient behavior of large hydrocarbons.
Technical Paper

The Effect of Enhanced Ignition Systems on Early Flame Development in Quiescent and Turbulent Conditions

1991-02-01
910564
Previous research on the effects of enhanced ignition systems has produced some conflicting results, possibly related to the various diagnostic methods used. In this investigation, several methods were used to measure the effects on flame development for different spark ignition circuits in quiescent and turbulent premixed gaseous mixtures. Sparks from a standard ignition circuit, typical of automotive use, were compared with sparks from a breakdown ignition circuit and from a plasma jet ignition circuit. It is shown that burning velocity calculation methods based on pressure trace analysis tend to be biased by any effects which provide a more spherical flame growth; particularly by projecting the spark kernel into the mixture away from the spark plug. Thus, the pressure trace-based burning velocity measurements gave false indications when comparing flames growing from dissimilar ignition systems.
Technical Paper

Detection of Catalyst Failure On-Vehicle Using the Dual Oxygen Sensor Method

1991-02-01
910561
On-vehicle proof-of-concept testing was conducted to evaluate the ability of the dual oxygen sensor catalyst evaluation method to identify serious losses in catalyst efficiency under actual vehicle operating conditions. The dual oxygen sensor method, which utilizes a comparison between an upstream oxygen sensor and an oxygen sensor placed downstream of the catalyst, was initially studied by the Environmental Protection Agency (EPA) under steady-state operating conditions on an engine dynamometer and reported in Clemmens, et al. (1).* At the time that study was released, questions were raised as to whether the technological concepts developed on a test fixture could be transferred to a vehicle operating under normal transient conditions.
Technical Paper

Impact of Methanol Fuel Blends on Activated Carbon Performance

1991-02-01
910563
Methanol-gasoline blends have attracted a great deal of attention as automotive fuels for both environmental and economic reasons. To better understand the effect of methanol concentration on activated carbon performance, cycling tests with new carbons and several different methanol:gasoline ratios were undertaken. The data obtained indicate that the keys to activated carbon performance with methanol-blended fuels are the pore size/volume characteristics. It was determined that the working capacity to breakthrough for methanol blends of 0, 10, and 35% by volume were similar but that the working capacity for 85% methanol was significantly lower. When the same carbon was cycled sequentially with gasoline and different concentrations of methanol, the adsorption/desorption performance tended to adjust or recover to levels expected.
Technical Paper

Performance of Multiple Stream Pulsed Jet Combustion Systems

1991-02-01
910565
In the course of our studies on pulsed jet combustion (PJC) a series of tests were carried out to determine the performance of multi-stream systems. This included multi-jet efflux, as well as dual-generator aggregates. The essential performance indicator of a PJC system is the pressure transducer record, yielding, in particular, data on the rise time and amplitude of the pressure pulse, as well as the rate of pressure rise. Concomitantly with pressure measurements, a sequence of schlieren records were obtained to reveal the salient features of the fluid mechanical phenomena of the PJC process. Elucidated thereby are the effects of entrainment induced by large scale vortex structures of turbulent jet plumes, and their decisive role in governing the process of combustion, as influenced by their particular configuration.
Technical Paper

The Use of Gas Dynamics to Link In-Cylinder and Exhaust System Unburnt Hydrocarbon Measurements on a Spark Ignition Engine

1991-02-01
910559
The paper reviews the ideas on the sources of unburnt hydrocarbons in spark ignition engines. Time resolved measurements made in-cylinder and in the exhaust system in previous investigations have revealed large differences between the cylinder and the exhaust system. It is not possible to distinguish between reductions by mixing and oxidation. The object of the present paper is to investigate the links between the two sets of measurements using a new development of engine gas dynamics. An outline is given of the authors' measurements and the new aspects of the gas dynamics model. The key idea of the latter is the introduction of “the path line streams”. A recent study using this method is described and the results discussed. It explains the role of mixing at entry to the exhaust valve annulus and the post flame oxidation process. It is concluded that the new technique has extensive possibilities in the understanding of the problem of unburnt hydrocarbons from reciprocating engines.
Technical Paper

Emission Factors for Small Utility Engines

1991-02-01
910560
Abstract A major gap exists in available baseline emissions data on the small utility engine population between the mid-1970's and present day. As part of the input required for a standard-setting process, the California Air Resources Board has funded limited laboratory emission measurements on a number of modern small engines, both 2-stroke and 4-stroke designs. Exhaust constituents characterized in this study include total hydrocarbons, reactive hydrocarbons (RHC), methane, CO, NOx, CO2, O2, aldehydes, and particulate matter. A total of nine engines were evaluated, spanning the range from the smallest widely-used 2-strokes (about 20 cc displacement) to 4-strokes approaching 20 hp.
Technical Paper

The Effect of Piston Temperature on Hydrocarbon Emissions from a Spark-Ignited Direct-Injection Engine

1991-02-01
910558
Light-load unburned hydrocarbon emissions were studied experimentally in a spark-ignited direct-injection engine burning gasoline where the piston temperature was varied. The test engine was a single-cylinder Direct Injection Stratified-Charge (DISC) engine incorporating a combustion process similar to the Texaco Controlled Combustion System. At a single low load operating condition, the piston temperature was varied by 50 K by controlling the cooling water and oil temperature. The effect of this change on unburned hydrocarbon emissions and heat release profiles was studied. It was found that by carefully controlling the intake air temperature and pressure to maintain constant in-cylinder conditions at the time of injection, the change in piston temperature did not have a significant effect on the unburned hydrocarbon emissions from the engine.
Technical Paper

Simultaneous Removal of NOx, SOx, and Soot in Diesel Engine Exhaust by Plasma/Oil Dynamics Means

1991-02-01
910562
Abstract The soot included in the exhaust gas from a diesel-engine vehicle (Nissan LD20, 2 liters) has been eliminated completely (100 %) independent of the load and cruising speed by a noveltechnique using a combination of discharge plasma and oil dynamics. As far as we know, this is the first success in suppressing the black exhaust gas. The NOx (NO2 + NO) and SOx components have also been reduced about 70 % at a lotation number of 1200 rpm and a load of 7kg-m (the maximum torque at 1200 rpm is about 11.4 kg m), corresponding to 60 % of full load. This simultaneous treatment has become possible by using oil. The SOx elimination is the first report in our investigation. Thus, the worst three air pollutants, soot, SOx and NOx, are removed simultaneously.
Technical Paper

Filiform Corrosion Resistance of Painted Automotive Body Sheet

1991-02-01
910556
Accelerated and outdoor exposure studies were conducted on three automotive body sheet alloys-2036, 2008, and 6009-in order to compare their filiform corrosion resistance after painting. The effect of variations in pretreatment and sanding prior to painting were studied and the amount of filiform corrosion was quantified. Both spray and immersion pretreatments were evaluated. A field survey of automobiles with 2036 alloy aluminum hoods in service for up to 10 years was conducted.
Technical Paper

Development of Substrate Formulation via Simplex Mixture Design

1991-02-01
910518
The intent of this paper is to demonstrate the benefits of using experimental design techniques in product formulations. In this example, an optimized product was developed using minimal experimental trials by the use of a simplex mixture design. The resultant product was tailored within mechanical property, weight, and cost constraints. The new formulation was developed, prototyped, and tested quickly in order to be available to substitute for a heavier, more expensive steel and aluminum part.
Technical Paper

Pre-Bent Effect on Binder Wrap of a Trunk Deck-Lid

1991-02-01
910515
An existing binder computer program including a pre-processor to establish a finite element model has been modified so that it can analyze the blank of a trunk deck-lid outer panel with pre-bend. The formula for computing the spring-back shape after a blank under cylindrical bending with a specific radius is derived in this paper. Using this spring-back shape as a starting configuration instead of a flat blank, the modified program computes the binder wrap of an automotive body panel. Two trunk deck-lid outer panels were analyzed to illustrate the effects of pre-bend.
Technical Paper

Blank Development and Metal Flow Analysis for Multi-Stage Drawing of Box Shaped Stampings

1991-02-01
910516
Blank development is the basis for calculating the material cost and hence the product cost, at the quoting stage. Understanding the metal flow under the binder is a critical activity during the tooling design stages, as well as during phototyping. The paper describes a computer aided blank development and metal flow analysis system, that will assist in performing the functions described above, before the tools are built, for box shaped parts drawn in multi-stage forming operations with a flat punch face, and a flat binder. Development of the minimum blank shape, using the SLF technique for shrink flanged components is not new. The paper addresses the extension of the approach to: i. multi-stage forming operations and, ii. the incorporation of the effect of thickness changes on the blank shape. Applications are given in the paper using the computer program BLANKDEV.
Technical Paper

Simplified Formability Analysis for Die Development and Production Troubleshooting

1991-02-01
910517
Formability analysis of automotive body stampings has typically employed use of circle grid analysis (CGA) techniques. These methods are widely accepted by users and suppliers throughout the industry. Although a proven means of measuring sheet metal deformation, the CGA methodology is not without drawbacks. Utilization of thickness strains to determine formability both compliments CGA and simplifies strain analysis. Using the constant volume equation, a four-step approach to thickness strain analysis (TSA) is provided. Differences between original and final thickness can be readily converted to strain readings and plotted on developed thickness strain diagrams (TSD). Also presented is a case study which illustrates effective TSA techniques during tooling development to ensure an adequate part safety margin. This alternative technique to formability analysis offers many benefits over traditional CGA methods.
Technical Paper

Obtaining LDH Stability

1991-02-01
910512
Abstract There are quite a few studies on the influences of coatings and base materials on the results of LDH (Limiting Dome Height) test.(1) Although these influences are hard to quantify, and the interdependence of one variable with the other makes interpreting the results even more complicated(2), a basic understanding has been achieved. The influence of temperature is not clear, but there are some indications that increasing temperatures have a detrimental effect on the LDH values. A previous investigation carried out at Ford Motor Company(3) on a QC LDH machine reveals that the LDH decreases with increasing temperature of the system (basically three temperatures were monitored: punch, binder and hydraulic oil reservoir). Such a behavior can have important consequences in the industrial implementation of the LDH test: if temperature has a significant effect, then the statistical value of the results is reduced.
Technical Paper

Approximate Formability Analysis of Two-Step Stretch Flanges

1991-02-01
910514
Abstract Many stretch flanges in sheet metal parts are formed from material which has been significantly strained in a previous forming operation. This paper uses the assumption of axisymmetry and an engineering approximation to develop a formula for the final flange length, given the shape of the intermediate configuration and the trim location. The maximum flange length is limited by splitting of the metal at the free edge, and the strain level at which splitting takes place depends strongly on the strain state and magnitude of the intermediate configuration. Using the above-mentioned formula with experimentally determined forming limits, a computer program is developed to calculate maximum flange lengths for balanced biaxial prestrain. Comparison is made to some limited experimental data.
Technical Paper

Stretch-Flange Formability of High-Strength Steel

1991-02-01
910513
A high stretch-flange formability is required of the suspension parts and road wheels. So, the factors effecting stretch-flange formability of hot rolled high strength steel sheet were investigated. The stretch-flange formability was evaluated with a punched hole expansion ratio (λ = d/d0). The inclusion (MnS etc.) deteriorates λ. The hole expansion property is affected by a microstructure. Bainite is most desirable. Incidentally, the form of the cementite in bainite has effect on it. Increase of Si accelerates a fine dispersion of cementite and improves the hole expansion property. The microstructure has the effect on the shape of burr on the punched face, a micro-crack condition or a crack propagation property and as the result, it affects the hole expansion property.
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