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Technical Paper

Numerical Modeling of Fuel Sprays in DISI Engines Under Early-Injection Operating Conditions

2000-03-06
2000-01-0273
Numerical calculations of the fuel spray structure from a high-pressure swirl injector were used to enable the interpretation of experimental observations obtained in hot, hollow-cone fuel sprays issued into sub-atmospheric-pressure environments. The experiments show that the spray becomes narrower, more compact, but with a relatively long penetration depth. Model input parameters, including the droplet size distribution, early vapor production, and initial cone angle, were modified to determine which spray characteristics are important in recreating observed spray structures. A very small mean droplet diameter is needed to recreate the experimentally observed structure of the high-temperature, low-pressure sprays. Vapor addition to the emerging spray is then required to increase the axial penetration and provide the observed vapor core.
Technical Paper

A Driver Behavior Recognition Method Based on a Driver Model Framework

2000-03-06
2000-01-0349
A method for detecting drivers' intentions is essential to facilitate operating mode transitions between driver and driver assistance systems. We propose a driver behavior recognition method using Hidden Markov Models (HMMs) to characterize and detect driving maneuvers and place it in the framework of a cognitive model of human behavior. HMM-based steering behavior models for emergency and normal lane changes as well as for lane keeping were developed using a moving base driving simulator. Analysis of these models after training and recognition tests showed that driver behavior modeling and recognition of different types of lane changes is possible using HMMs.
Technical Paper

Effects of Fuel Volatility and Operating Conditions on Fuel Sprays in DISI Engines: (1) Imaging Investigation

2000-03-06
2000-01-0535
Optimal design of modern direct injection spark-ignition engines depends heavily on the characteristics and distribution of the fuel spray. This study was designed to investigate changes in the spray properties due to fuel volatility and operating conditions using a firing optically-accessible engine with planar laser-induced fluorescence (PLIF) imaging. The results show that the spray structure changes not only with ambient gas density, which is often measured, but also with fuel temperature and volatility. As ambient pressure decreases and fuel temperature increases, the volatile ends of multi-component fuels evaporate quickly, disrupting the spray structure and producing a vapor core along the axis of the spray. Beyond a certain point, evaporation is rapid enough to expand the initial cone angle of the spray while causing a decrease in the overall spray width.
Technical Paper

Effects of Fuel Volatility and Operating Conditions on Fuel Sprays in DISI Engines: (2) PDPA Investigation

2000-03-06
2000-01-0536
Optimal design of modern direct injection spark-ignition engines depends heavily on the characteristics and distribution of the fuel spray. This study was designed to compliment imaging experiments of changes in the spray structure due to fuel volatility and operating conditions. Use of phase-Doppler particle analysis (PDPA) allows quantitative point measurements of droplet diameter and velocity. In agreement with imaging experiments, the results show that the spray structure changes not only with ambient gas density, which is often measured, but also with fuel temperature and volatility. The mean droplet diameter was found to decrease substantially with increasing fuel temperature and decreasing ambient density. Under conditions of low potential for vaporization, the observed trends in mean droplet sizes agree with published correlations for pressure-swirl atomizers.
Technical Paper

Particulate Matter Emission During Start-up and Transient Operation of a Spark-Ignition Engine (2): Effect of Speed, Load, and Real-World Driving Cycles

2000-03-06
2000-01-1083
Previous research into Particulate Matter (PM) emissions from a spark-ignition engine has shown that the main factor determining the how PM emissions respond to transient engine operating conditions is the effect of those conditions on intake port processes such as fuel evaporation. The current research extends the PM emissions data base by examining the effect of transient load and speed operating conditions, as well as engine start-up and shut-down. In addition, PM emissions are examined during “real-world” driving conditions - specifically, the Federal Test Procedure. Unlike the previous work, which was performed on an engine test stand with no exhaust gas recirculation and with a non-production engine controller, the current tests are performed on a fully-functional, production vehicle operated on a chassis dynamometer to better examine real world emissions.
Technical Paper

Novel Near-Net-Shape Tool-Less Method for Manufacturing of Cast Metal Matrix Composites: Three-Dimensional Printing (3DP) of Ceramic Preforms Combined with Investment Casting Technology

2000-03-06
2000-01-0675
New three-dimensional printing technology (3DP) developed at MIT was tried as a manufacturing method to fabricate ceramic preforms for a discontinuously reinforced metal matrix composites. Minor modifications to the “legacy” 3DP technology allowed to produce such preforms successfully. Preforms were then infiltrated with liquid aluminum resulting in composite materials as strong as produced via conventional methods. Net shape connecting rod preforms were 3D-printed and used to produce composite connecting rods without building any molds or tooling using novel Tool-less Mold™ technology.
Technical Paper

Detailed Calculation of Heating, Evaporation, and Reaction Processes of a Thin Liquid Layer of Hydrocarbon Fuel

2000-03-06
2000-01-0959
A one-dimensional model has been developed for the species and energy transfer over a thin (0.1-0.5 mm) layer of liquid fuel present on the wall of a spark-ignition engine. Time-varying boundary conditions during compression and flame passage were used to determine the rate of methanol vaporization and oxidation over a mid-speed, mid-load cycle, as a function of wall temperature. The heat of vaporization and the boiling point of the fuel were varied about a baseline to determine the effect of these characteristics, at a fixed operating point and lean conditions (ϕ = 0.9). The calculations show that the evaporation of fuels from layers on cold walls starts during flame passage, peaking a few milliseconds later, and continuing through the exhaust phase.
Technical Paper

Non-Linear Analysis of Vehicle Dynamics (NAVDyn): A Reduced Order Model for Vehicle Handling Analysis

2000-05-01
2000-01-1621
Many vehicle-dynamics models exist to study the motion of a vehicle. Most of these models fall into one of two categories: very simple models for basic analyses and high-order models consisting of many degrees-of-freedom. For many scenarios, the simple models are not adequate. At the same time, for many vehicle handling and braking studies, the high-order models are more complex than necessary. This paper presents a model that includes the dynamics that are relevant to studying vehicle handling and braking, but is still simple enough to run in near real-time. The model was implemented in such a way that it is easily customized for a particular study. Predictions from this simplified model were compared against a high-order model and against actual vehicle test data. The simulations indicate a close agreement in the results.
Technical Paper

Design of an Automotive Compressor Production System Using Lean Manufacturing Design Guidelines

1999-05-10
1999-01-1622
The design of a new production system requires a framework for ensuring that high level system objectives are satisfied by all subsystems and components. Since production system design is a multidisciplinary activity that extends beyond the boundary of any single company, a means to communicate these objectives and provide understanding to outside vendors and suppliers is also important. This paper describes both the framework and guidelines used to design a production system for a recently developed automotive compressor. The actual production system that was designed is given along with specific system and equipment examples originating from the design guidelines. These examples also show how the low level design decisions satisfied high-level system requirements.
Technical Paper

Design of Manufacturing Systems to Support Volume Flexibility

1999-05-10
1999-01-1621
This paper presents an Axiomatic Design framework for manufacturing system design and illustrates how lean cellular manufacturing can achieve volume flexibility. Axiomatic Design creates a design framework by mapping the functional requirements of a system to specific design parameters. Volume flexibility is often neglected as a requirement of manufacturing systems. Very few industries are fortunate enough to experience stable or predictable product demand. In reality, demand is often volatile and uncertain. It is important that manufacturing system designers are aware of manufacturing system types which can accommodate volume flexibility and follow a structured design methodology that assures that all requirements are met by the system.
Technical Paper

Application of a Lean Cellular Design Decomposition to Automotive Component Manufacturing System Design

1999-05-10
1999-01-1620
A design framework based on the principles of lean manufacturing and axiomatic design was used as a guideline for designing an automotive component manufacturing system. A brief overview of this design decomposition is given to review its structure and usefulness. Examples are examined to demonstrate how this design framework was applied to the design of a gear manufacturing system. These examples demonstrate the impact that low-level design decisions can have on high-level system objectives and the need for a systems-thinking approach in manufacturing system design. Results are presented to show the estimated performance improvements resulting from the new system design.
Technical Paper

Integrating the Production Information System with Manufacturing Cell Design - A Lean, Linked Cell Production System Design Implementation

1999-05-10
1999-01-1634
The linked cell system gives both reduced cost and volume flexibility. The characteristics of the linked cell system are a consequence of decoupling the operators from the machines, using standard work in process between the cells and by integrating the information system with the cell and system design. By decoupling the operators from the machines the capacity can be increased/decreased in small increments by using more or fewer operators in the cell. The information system is integrated with the linked cell design by the use of a Heijunka box. The Heijunka is used to level production and to initiate the pace of production as a result of pulling withdrawal kanban at a standard time interval. This standard time interval is called the pitch of production. The kanban cards give information about what to produce, when to produce, when to make changeovers but they also give information to control the material replenishment.
Technical Paper

The Importance of Takt Time in Manufacturing System Design

1999-05-10
1999-01-1635
Lean production has greatly influenced the way manufacturing systems should be designed. One important aspect of lean production is takt time. Takt time relates customer demand to available production time and is used to pace the production. This paper applies the manufacturing system design and deployment framework to describe the impact of takt time on both the design and the operation of a manufacturing system. The goal of this paper is to illustrate the relevant relationships of takt time to overall system design.
Technical Paper

The Production System Design and Deployment Framework

1999-05-11
1999-01-1644
This session keynote paper presents a framework for designing and deploying production systems. The framework enables the communication and determination of objectives and design solutions from the highest level to the lowest level of a manufacturing enterprise. The design methodology ensures that the physical implementation, called Design Parameters (DPs), meets the objectives or Functional Requirements (FRs) of the production system design. This paper presents a revolutionary approach to determine the objectives and the implementation of a “lean” production system design for a manufacturing business as guided by the design axiom of independence.
Technical Paper

An Adaptive Air/Fuel Ratio Controller for SI Engine Throttle Transients

1999-03-01
1999-01-0552
An adaptive air/fuel ratio controller for SI engine throttle transient was developed. The scheme is based on an event- based, single- parameter fuel dynamics model. A least- square- error algorithm with an active forgetting factor was used for parameter identifications. A one- step- look- ahead controller was designed to maintain the desired air/fuel ratio by canceling the fuel dynamics with the controller setting updated adaptively according to the identified parameters. When implemented on a Ford Ztech engine and tested under a set of throttle- transient operations, the adaptive controller learned quickly and performed well.
Technical Paper

Evaporation of In-Cylinder Liquid Fuel Droplets in an SI Engine: A Diagnostic-Based Modeling Study

1999-03-01
1999-01-0567
Liquid fuel behavior in the cylinder impacts SI engine HC emissions particularly during engine start-up. Inflow of liquid fuel into the cylinder is largely determined by the flow and temperature environment in the intake port. Subsequent evaporation of fuel droplets in the cylinder prior to impact on the piston and cylinder liner reduces the amount of liquid fuel in the cylinder that is likely to contribute to HC emission and is therefore important. In this study, measurements of liquid fuel droplet characteristics in the vicinity of the intake valve of a firing SI engine were analyzed to estimate the amount and spatial distribution of in-cylinder evaporation of liquid fuel prior to droplet impact on the cylinder liner or piston. A one-dimensional fuel droplet evaporation model was developed to predict the amount of fuel evaporation given measured fuel droplet sizes and velocities, intake port and valve temperatures during warm up, and cylinder geometry.
Technical Paper

Effect of Engine and Fuel Variables on Liquid Fuel Transport into the Cylinder in Port-Injected SI Engines

1999-03-01
1999-01-0563
Liquid fuel inflow into the cylinder is considered to be an important source of exhaust hydrocarbon (HC) emissions from automotive spark ignition engines. These liquid-fuel-caused emissions are increased significantly during the start up and subsequent warm-up period. This study analyzes the influence of several engine and injector design variables, and fuel parameters, on the in-cylinder liquid fuel behavior. The effect of the following parameters on the characteristics of the fuel droplets entering the cylinder was studied: Fuel volatility, injection timing, intake valve timing, injector type, spray geometry, and spray targeting in the intake port. A Phase Doppler Particle Analyzer (PDPA) was used in a single-cylinder flow visualization combustion engine to assess this in-cylinder liquid fuel behavior. Measurements of fuel droplet characteristics (size and velocity) were taken in selected locations in the vicinity of the intake valve during starting and warm up.
Technical Paper

The Theory of Cost Risk in Design

1999-03-01
1999-01-0495
In a recent paper (Hoult & Meador, [1]) a novel method of estimating the costs of parts, and assemblies of parts, was presented. This paper proposed that the metric for increments of cost was the function log (dimension/tolerance). Although such log functions have a history,given in [1], starting with Boltzman and Shannon, it is curious that it arises in cost models. In particular, the thermodynamic basis of information theory, given by Shannon [2], seems quite implausible in the present context. In [1], we called the cost theory “Complexity Theory”, mainly to distinguish it from information theory. A major purpose of the present paper is to present a rigorous argument of how the log function arises in the present context. It happens that the agrument hinges on two key issues: properties of the machine making or assembling the part, and a certain limit process. Neither involves thermodynamic reasoning.
Technical Paper

Development and Applications of an Analytical Tool for Piston Ring Design

2003-10-27
2003-01-3112
A comprehensive and robust analytical tool was developed to study three-dimensional (3D) ring-bore and ring-groove interactions for piston rings with either symmetric or asymmetric cross-section. The structural response of the ring is modeled with 3D finite element beam method, and the interfaces between the ring and the bore as well as between the ring and the groove are modeled with a simple asperity contact model. Given the ring free shape and the geometry of the cross-section, this analytical tool can be used to evaluate the ring-bore and ring-groove conformability as well as ring twist angle distribution under different constraints. Conversely, this tool can be used to calculate the free shape to provide the desired ring-bore contact pressure distribution for specific applications.
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