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Technical Paper

Inverse Method for Measuring Weld Temperatures during Resistance Spot Welding

2001-03-05
2001-01-0437
A new monitoring system predicts the progression of welding temperature fields during resistance spot welding. The system captures welding voltages and currents to predict contact diameters and simulate temperature fields. The system accurately predicts fusion lines and heat-affected zones. Accuracy holds even for electrode tips used for a few thousand welds of zinc coated steels.
Technical Paper

Piston Fuel Film Observations in an Optical Access GDI Engine

2001-05-07
2001-01-2022
A gasoline direct injection fuel spray was observed using a fired, optical access, square cross-section single cylinder research engine and high-speed video imaging. Spray interaction with the piston is described qualitatively, and the results are compared with Computational Fluid Dynamics (CFD) simulation results using KIVA-3V version 2. CFD simulations predicted that within the operating window for stratified charge operation, between 1% and 4% of the injected fuel would remain on the piston as a liquid film, dependent primarily on piston temperature. The experimental results support the CFD simulations qualitatively, but the amount of fuel film remaining on the piston appears to be under-predicted. High-speed video footage shows a vigorous spray impingement on the piston crown, resulting in vapor production.
Technical Paper

Space Life Support from the Cellular Perspective

2001-07-09
2001-01-2229
Determining the fundamental role of gravity in vital biological systems in space is one of six science and research areas that provides the philosophical underpinning for why NASA exists. The study of cells, tissues, and microorganisms in a spaceflight environment holds the promise of answering multiple intriguing questions about how gravity affects living systems. To enable these studies, specimens must be maintained in an environment similar to that used in a laboratory. Cell culture studies under normal laboratory conditions involve maintaining a highly specialized environment with the necessary temperature, humidity control, nutrient, and gas exchange conditions. These same cell life support conditions must be provided by the International Space Station (ISS) Cell Culture Unit (CCU) in the unique environment of space. The CCU is a perfusion-based system that must function in microgravity, at unit gravity (1g) on earth, and from 0.1g up to 2g aboard the ISS centrifuge rotor.
Technical Paper

What Is a Car? Beyond Electronics

2000-11-01
2000-01-C029
A car today presents itself under many guises: as an "office on wheels,'' a "family space,'' a "toy,'' a "sports car,'' a go-anywhere vehicle, or some hybrid combination. What it means to "drive'' consequently is also changing to include more and more secondary activities over and above the primary activity of "vehicle control.'' As the car continues to evolve, electronics plays a large role, particularly in the development of secondary activities such as entertainment and communications, and as mechanical functions are gradually replaced by electronics. Nevertheless, despite the obvious extension of the functionality of the vehicle, and its continuing improvements, there is a growing concern today that the passenger vehicle may be losing emotional resonance with the customer. The fear is that it might simply become a commodified "wheeled conveyance'' or even an "appliance,'' despite all efforts to increase its functionality and usefulness.
Technical Paper

A New Design for Automotive Alternators

2000-11-01
2000-01-C084
This paper introduces a new design for alternator systems that provides dramatic increases in peak and average power output from a conventional Lundell alternator, along with substantial improvements in efficiency. Experimental results demonstrate these capability improvements. Additional performance and functionality improvements of particular value for high-voltage (e.g., 42 V) alternators are also demonstrated. Tight load-dump transient suppression can be achieved using this new design and the alternator system can be used to implement jump charging (the charging of the high-voltage system battery from a low-voltage source). Dual-output extensions of the technique (e.g., 42/14 V) are also introduced. The new technology preserves the simplicity and low cost of conventional alternator designs, and can be implemented within the existing manufacturing infrastructure.
Technical Paper

Modeling NO Formation in Spark Ignition Engines with a Layered Adiabatic Core and Combustion Inefficiency Routine

2001-03-05
2001-01-1011
A thermodynamic based cycle simulation which uses a thermal boundary layer, either, a fully mixed or layered adiabatic core, and a crevice combustion inefficiency routine has been used to explore the sensitivity of NO concentration predictions to critical physical modeling assumptions. An experimental database, which included measurements of residual gas fraction, was obtained from a 2.0 liter Nissan engine while firing on propane. A model calibration methodology was developed to ensure accurate predictions of in-cylinder pressure and burned gas temperature. Comparisons with experimental NO data then showed that accounting for temperature stratification during combustion with a layered adiabatic core and including a crevice/combustion inefficiency routine, improved the match of modeling predictions to data, in comparison to a fully mixed adiabatic core.
Technical Paper

Prediction of the Knock Limit and Viable Operating Range for a Homogeneous-Charge Compression-Ignition (HCCI) Engine

2003-03-03
2003-01-1092
A method is presented for predicting the viable operating range of homogeneous-charge compression-ignition (HCCI) engines. A fundamental criterion for predicting HCCI knock is described and used to predict the minimum air/fuel ratio (and hence maximum torque) available from the engine. The lean (misfire) limit is computed using a modification of the multi-zone method of Aceves et al. [1]. Numerical improvements are described which allow even very complex fuel chemistry to be rapidly modeled on a standard PC. The viable operating range for an HCCI engine burning a primary reference fuel (PRF 95) is predicted and compared with literature experimental data. The new ability to accurately predict the operating range for any given HCCI engine/fuel combination should considerably simplify the tasks of designing a robust engine and identifying suitable fuels for HCCI.
Technical Paper

Time-Resolved, Speciated Emissions from an SI Engine During Starting and Warm-Up

1996-10-01
961955
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.
Technical Paper

Numerical Simulation of Post-Flame Oxidation of Hydrocarbons in Spark Ignition Engines

1997-02-24
970886
About 50-90 percent of the hydrocarbons that escape combustion during flame passage in spark-ignition engine operation are oxidized in the cylinder before leaving the system. The process involves the transport of unreacted fuel from cold walls towards the hotter burned gas regions and subsequent reaction. In order to understand controlling factors in the process, a transient one-dimensional reactive-diffusive model has been formulated for simulating the oxidation processes taking place in the reactive layer between hot burned gases and cold unreacted air/fuel mixture, with initial and boundary conditions provided by the emergence of hydrocarbons from the piston top land crevice. Energy and species conservation equations are solved for the entire process, using a detailed chemical kinetic mechanism for propane.
Technical Paper

Liquid Fuel Transport Mechanisms into the Cylinder of a Firing Port-Injected SI Engine During Start Up

1997-02-24
970865
The occurrence of liquid fuel in the cylinder of automotive internal combustion engines is believed to be an important source of exhaust hydrocarbon (HC) emissions, especially during the warm-up process following an engine start up. In this study a Phase Doppler Particle Analyzer (PDPA) has been used in a transparent flow visualization combustion engine in order to investigate the phenomena which govern the transport of liquid fuel into the cylinder during a simulated engine start up process. Using indolene fuel, the engine was started up from room temperature and run for 90 sec on each start up simulation. The size and velocity of the liquid fuel droplets entering the cylinder were measured as a function of time and crank angle position during these start up processes. The square-piston transparent engine used gave full optical access to the cylinder head region, so that these droplet characteristics could be measured in the immediate vicinity of the intake valve.
Technical Paper

Economic and Environmental Tradeoffs in New Automotive Painting Technologies

1998-02-23
981164
Painting is the most expensive unit operation in automobile manufacturing and the source of over 90 percent of the air, water and solid waste emissions at the assembly plant. While innovative paint technologies such as waterborne or powder paints can potentially improve plant environmental performance, implementing these technologies often requires major capital investment. A process-based technical cost model was developed for examining the environmental and economic implications of automotive painting at the unit operation level. The tradeoffs between potential environmental benefits and their relative costs are evaluated for current and new technologies.
Technical Paper

Increased Power Density via Variable Compression/Displacement And Turbocharging Using The Alvar-Cycle Engine

1998-02-23
981027
This paper presents the analysis and design of a variable compression-ratio and displacement engine concept - the Alvar Cycle using a four-stroke engine-performance simulation. The Alvar-Cycle engine uses secondary pistons which reciprocate in auxiliary chambers housed in the cylinder head, at adjustable phase-angle differences from the primary pistons. The phase difference provides both the variable total engine displacement and compression ratio. Results indicate that the Alvar engine can operate at higher power density via a combination of higher intake boost and lower compression ratio to avoid knock at high loads, and capture the better thermal efficiency at higher compression ratios at part loads.
Technical Paper

Investigation of the Dilution Process for Measurement of Particulate Matter from Spark-Ignition Engines

1998-10-19
982601
Measurements of particulate matter (PM) from spark ignition (SI) engine exhaust using dilution tunnels will become more prevalent as emission standards are tightened. Hence, a study of the dilution process was undertaken in order to understand how various dilution related parameters affect the accuracy with which PM sizes and concentrations can be determined. A SI and a compression ignition (CI) engine were separately used to examine parameters of the dilution process; the present work discusses the results in the context of SI exhaust dilution. A Scanning Mobility Particle Sizer (SMPS) was used to measure the size distribution, number density, and volume fraction of PM. Temperature measurements in the exhaust pipe and dilution tunnel reveal the degree of mixing between exhaust and dilution air, the effect of flowrate on heat transfer from undiluted and diluted exhaust to the environment, and the minimum permissible dilution ratio for a maximum sample temperature of 52°C.
Technical Paper

Chain Representations of Dimensional Control: A Producibility Input for Concurrent Concept Design

1998-06-02
981846
Two critical milestones that must be achieved during concept design are 1) definition of a product architecture that meets performance, producibility, and strategic objectives, and 2) estimation of the integration risk in each candidate concept. This paper addresses these issues by describing the role played by the producibility members of an Integrated Product Team (IPT) during concept design. Our focus is on the execution of the what we call the “chain method”, which illustrates the structure of function delivery in a concept in a simple pictorial way and helps the IPT to understand the advantages or disadvantages of using a modular or an integral product architecture. The producibility members play a central role in capturing and evaluating the chains for different candidate concepts and decompositions.
Technical Paper

Liquid Fuel Visualization Using Laser-Induced Fluoresence During Cold Start

1998-10-19
982466
The presence of liquid fuel inside the engine cylinder is believed to be a strong contributor to the high levels of hydrocarbon emissions from spark ignition (SI) engines during the warm-up period. Quantifying and determining the fate of the liquid fuel that enters the cylinder is the first step in understanding the process of emissions formation. This work uses planar laser induced fluorescence (PLIF) to visualize the liquid fuel present in the cylinder. The fluorescing compounds in indolene, and mixtures of iso-octane with dopants of different boiling points (acetone and 3-pentanone) were used to trace the behavior of different volatility components. Images were taken of three different planes through the engine intersecting the intake valve region. A closed valve fuel injection strategy was used, as this is the strategy most commonly used in practice. Background subtraction and masking were both performed to reduce the effect of any spurious fluorescence.
Technical Paper

Fuel Effects and Enrichment Effects on Engine Starting and Warm-Up Behavior

1995-02-01
950065
The effects of fuel volatility and degree of enrichment on the starting and warm-up behavior of a modern four-valve spark ignition engine with port-fuel-injection were studied. Quantities of interest are the number of cycles to reach first significant firing, the time scale (τr) for the IMEP development, the decay rate of the IMEP fluctuation, and the RMS fluctuation after 3τr. A selected matrix of fuels that included various volume ratios of indolene/MTBE and iso-octane/n-pentane was used. The amount of fuel injected per cycle was varied from stoichiometric to a fuel equivalence ratio of 1.5. The engine behavior (as quantified by the quantities described in the above) is found to correlate well to a single parameter - the fuel equivalence ratio based on the fuel vapor mass calculated from an isothermal equilibrium flash vaporization of the fuel in the vapor boundary layer of the intake flow at intake manifold temperature.
Technical Paper

A Model for Converting SI Engine Flame Arrival Signals into Flame Contours

1995-02-01
950109
A model which converts flame arrival times at a head gasket ionization probe, used in a spark-ignition engine, into flame contours has been developed. The head gasket was manufactured at MIT using printed circuit board techniques. It has eight electrodes symmetrically spaced around the circumference (top of cylinder liner) and it replaces the conventional head gasket. The model is based on engine flame propagation rate data taken from the literature. Data from optical studies of S.I. engine combustion or studies utilizing optical fiber or ionization probe diagnostics were analyzed in terms of the apparent flame speed and the entrainment speed (flame speed relative to the fluid ahead of the flame). This gives a scaling relationship between the flame speed and the mass fraction burned which is generic and independent of the chamber shape.
Technical Paper

Analysis of Fuel Behavior in the Spark-Ignition Engine Start-Up Process

1995-02-01
950678
An analysis method for characterizing fuel behavior during spark-ignition engine starting has been developed and applied to several sets of start-up data. The data sets were acquired from modern production vehicles during room temperature engine start-up. Two different engines, two control schemes, and two engine temperatures (cold and hot) were investigated. A cycle-by-cycle mass balance for the fuel was used to compare the amount of fuel injected with the amount burned or exhausted as unburned hydrocarbons. The difference was measured as “fuel unaccounted for”. The calculation for the amount of fuel burned used an energy release analysis of the cylinder pressure data. The results include an overview of starting behavior and a fuel accounting for each data set Overall, starting occurred quickly with combustion quality, manifold pressure, and engine speed beginning to stabilize by the seventh cycle, on average.
Technical Paper

Research Alliances, A Strategy for Progress

1995-09-01
952146
In today's business climate rapid access to, and implementation of, new technology is essential to enhance competitive advantage. In the past, universities have been used for research contracts, but to fully utilize the intellectual resources of education institutions, it is essential to approach these relationships from a new basis: alliance. Alliances permit both parties to become active participants and achieve mutually beneficial goals. This paper will examine the drivers and challenges for industrial -- university alliances from both the industrial and academic perspectives.
Technical Paper

Effects of Lubrication System Parameters on Diesel Particulate Emission Characteristics

1996-02-01
960318
The effects of lubrication system parameters on particulate emission rate and composition were studied. Engine load, viscosity and piston-ring gap were varied. Particulate rate and composition were measured for multiple combinations of lubricant and ring-gap configurations at three different engine operating conditions. Particulate rates were higher with the lower viscosity oil and larger with the wider top-ring gap. At high load, the difference in particulate rate was due to changes in the non-soluble portion, while at medium and low loads, the change in particulate rate was due to differences in the lubricant-derived portion of the soluble organic fraction (SOF). Additionally, changes in the fuel-derived portion of the SOF were discovered and attributed to changes in fuel-absorption in the oil film.
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