Fuel/Air Mixing and Combustion in a High-Speed Direct Injection Diesel
C. F. Lee,* J. E. Peters,* W. S. Mathews, J. A. Cellarius
U.S. Department of Energy, 99-DOE SBC-L/P-0030; Ford Motor Co.

The objective of the proposed work is to provide detailed information on the mixing and combustion processes in a small bore HSDI engine through in-cylinder measurements of (1) fuel spray penetration, mixing and interaction with the bowl geometry using Exciplex Planar Laser Induced Fluorescence, (2) ignition and combustion using natural flame emission and (3) soot formation using Laser Induced Incandescence as a function of engine operating conditions. The experiments will be conducted on a single cylinder research engine based on the Ford Diata modified for optical access using a Bowditch piston arrangement.

Integrated Vehicle Dynamics
A. G. Alleyne,* S. Brennan, D. Lynch
University of Illinois

Presently, components of the vehicle act independently of one another to control various aspects of the vehicle's dynamics. In this research, the dynamics of a moving vehicle are controlled by coordinating and integrating the various subsystems of the chassis. Wheel torque, steering forces, and suspension forces are combined in a synergistic approach to achieve levels of vehicle performance and safety that are superior to previous approaches. Extensive use of modern control techniques is made to determine the optimal combination of forces.

Modeling and Experiment of Spray Impingement and Film Flow and Back-Flow Atomization of Port Injection Engines
C. F. Lee,* J. E. Peters,* M. F. Trujillo, W. S. Mathews, J. A. Colwell
Ford Motor Co.; Amoco

To understand and improve fuel preparation of port-injection engines, multidimensional models are being developed for spray impingement on the wall, fuel film formation and transport, and atomization due to the back flow from the cylinder into the intake port upon intake valve opening. P/DPA, digital imaging, and light reflection measurements of drop size and velocity, film spreading rate, and film thickness will be conducted under controlled conditions specifically designed to provide a set of data for direct comparison with the modeled results. The calibrated models will then be used to study the port-injection and back-flow processes in the engines.

Modeling and Experiments of Lean Direct-Injection, Four-Stroke Spark-Ignition Engines
C. F. Lee,* D. L. Chang, J. Powell
National Science Foundation, CTS-9734402

A lean direct-injection spark-ignition engine concept has the potential of reducing fuel consumption and increasing performance while obtaining cleaner exhaust gas and greater driver comfort. The key research need of this type of engine is to develop a better understanding and control of in-cylinder fuel injection, atomization, vaporization, and mixing. The objective of this research program is to study the fuel sprays and air mixing process in direct-injection, four-stroke, spark-ignition engines using the latest multi-dimensional modeling and laser diagnostics techniques. Direct injection strategies currently under consideration by industry will be used and the effects of key variables such as injector timing, atomization quality, air motion, and engine geometry will be investigated.

Modeling of Cavitating Flows in High-Pressure Fuel Injectors
C. F. Lee,* H. M. Wasfy
Cummins Engine Co.

Flow cavitation is considered as a major problem affecting the performance of high-pressure diesel injectors. The cavitating flow is a two-phase flow by nature with gaseous phase generally dispersed within the liquid phase in the form of minute bubbles. Since it is computationally impossible to simulate each bubble as it forms, the model is needed for calculating the amount of mass trapped in the bubbles to compute averaged fluid properties, and for tracking the formation and destruction processes of the bubbles. The impact of the bubble dynamics on the injector flow will also studied.

Modeling of Multicomponent Fuel Evaporation in Engines
C. F. Lee,* Y. B. Zeng
Ford Motor Co.

The heating and gasification of liquid fuel droplets and films during the intake and compression strokes of a SI engine are important for fuel/air mixture preparation and cold-start emission. The amount of the liquid droplets entering the cylinder is strongly influenced by the type of fuel used. A fuel blend was chosen in order to match the distillation curve for the gasoline. Evaporation models of multicomponent fuel droplets and films are developed. The models will be verified against vaporization measurements of single droplet and exciplex measurements of low and high volatility fuel liquid and vapor distributions in the port-injection engine. The model will then be used to study the detailed mixture preparation process.

Port Injection Studies
J. E. Peters,* R. A. White,* R. P. Lucht,* C. F. Lee,* J. P. Styron, J. A. Colwell
Amoco; Ford Motor Co.; U. S. Department of Energy, SNL LD 7124D

The preparation of fuel and air mixtures during cold start conditions for port injection systems is being investigated. Because cold start emissions of unburned hydrocarbons are strongly influenced by the presence of liquid fuel in the combustion chamber, this study seeks to develop an improved understanding of the fuel preparation process as it relates to cold start atomization and mixing. Laser diagnostics are being used to study liquid atomization, vaporization, and mixing with air in the intake port and cylinder as a function of engine variables including valve lift, air flow, manifold geometry, and fuel injector type.

Study of Fuel-Air Distribution and Combustion in Direct-Injection Diesel Engines
C. F. Lee,* H. M. Wasfy, J. H. Zhang
Cummins Engine Co.

The diesel engine is the leading heavy-duty power plant because of its superior energy efficiency. However, diesel industries face increasingly stringent emission regulations in both nitric oxides and particulates. A detailed understanding of combustion is required to effectively reduce emissions while maintaining engine fuel economy. A multidimensional model, which has been tested extensively in various engine environments, is used to characterize the fuel/air mixing and combustion in the engine. Direct injection strategies currently under consideration by Cummins will be studied and the effects of injection rate and timing, EGR, and three-dimensionality on combustion will be investigated.

The Effects of In-Cylinder Wall Wetting on Hydrocarbon Emissions
C. F. Lee,* S. T. Chin
University of Illinois

The effect of combustion chamber wall-wetting on the hydrocarbon emissions from gasoline-fueled SI engines will be investigated using multidimensional engine computations. The latest multicomponent film vaporization model that was successfully developed and verified in our laboratory will be employed in this study. The combustion model will be improved to account for flame quenching near the walls. The results will be compared against the experimental data. Preliminary results indicate that the location where liquid fuel impinges on the combustion chamber has a significant effect on the hydrocarbon emissions.

Vibration Isolation Applied to Automotive Suspension Systems
A. G. Alleyne*
University of Illinois

The controllable flow of energy into and out of a vehicle suspension is studied in two phases: active control and semiactive control. Active control means being able to remove and/or add energy to the suspension from an external power source. Performance comparisons between active suspensions and passive suspensions, capable of only constant energy removal rates, demonstrate the benefits of the active systems. Semiactive control means being able to control the rate of energy removal but not being able to add energy to the system. Both approaches are investigated using theory, simulation, and experiment.