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Use of the two-stroke principle is favored in many small, lightweight engine applications. However, in its simplest form the two-stroke exhibits high specific fuel consumption and hydrocarbon emissions, and poor low speed, light load running quality. The need to resolve these problems and produce an environmentally friendly two-stroke engine has led to a variety of research and development efforts. At Michigan Technological University a marine-based two-stroke engine cylinder was reconfigured, with the objective of mitigating the low speed, light load problem. The cylinder utilizes auxiliary low speed ports which, when activated, are designed to reduce the trapped cylinder volume, and provide a higher purity trapped charge prior to combustion. Test results are reported for both intake and direct injection fuel delivery systems, and show that the reconfigured cylinder has improved low speed running characteristics.

The objective of this research was to evaluate the effects that higher fluid injection pressures and nozzle geometry have on compound fuel injector nozzle performance. Higher pressures are shown to significantly reduce droplet size, increase the discharge coefficient and reduce the overall size of a nozzle spray. It is also shown that the geometry has a significant effect on nozzle performance, and it can be manipulated to give a desired spray shape.

A computational design of experiments was constructed to analyze two basic nozzle designs. Several geometric features of the nozzles such as cavity height, exit orifice area, turbulence generator area and exit orifice position in addition to the pressure differential across the injector were used in a 2k factorial design study. Performance characteristic which were analyzed in an analysis of variance study included the discharge coefficient. atomization efficiency and predicted spray pattern. The computational design of experiments revealed which of the studied parameters had the greatest influence on a given nozzle performance characteristic. These results were compared to a similar investigation which was later performed experimentally from which similar conclusions were drawn.

The primary goal of this research was to investigate the feasibility of measuring the oil film thickness in a journal bearing using an optical film thickness sensor earlier developed at Michigan Technological University. A bearing oil film thickness testing facility was designed to provide precise control of the sensor calibration and experimental measurements. The calibration of the sensor was achieved by the use of an in-bearing calibration setup that allowed manual changes of film thickness by moving the bearing sensor within the bearing. By varying the speed from 350 to 1100 RPM and the load from 0 to 55 kg in a journal bearing, the sensor was able to measure changes in oil film thickness from 0 to 25 μm. The trends caused by changing the load or speed were seen to be consistent with a mathematical model based on the two dimensional Reynolds equation for journal bearing design.

Increasingly stringent emissions regulations and customer demands for high efficiency and smooth performance demand highly accurate control of the air-fuel ratio of automotive spark-ignition engines. Electronic port fuel injection provides the necessary control by adding a precise quantity of fuel for a given amount of air drawn in by the engine. Ideally, the metered fuel will consist only of fine droplets and vapor. In reality, the fuel spray impinges upon the walls of the intake port, creating a liquid fuel film. The fundamentally different transport mechanisms of the liquid fuel compared to vapor or fine droplets greatly complicates; the analysis of the fuel delivery system. Past research has provided models of fuel film dynamics in intake ports of port-fuel-injected engines, yet to date no practical method of measuring fuel films has been presented.

The fluid flow characteristics inside compound silicon micro machined port fuel injector nozzles were analyzed through the use of computational fluid dynamics (CFD). This study was undertaken in order to gain a better understanding of the fluid mechanics taking place in the compound orifice plate. In addition, the calculated computational results will be used to predict the fuel spray patterns and sauter mean diameters of the sprays. The influence of orifice plate geometry on calculated turbulent kinetic energies and fuel spray patterns was also studied and will be discussed. The results of this investigation indicate that the fluid flow characteristics inside the compound silicon micro machined port fuel injector nozzle are influenced by the geometries of the compound orifice plate, and that the flow characteristic inside the orifice plate effect the type of spray produced by the injector.

The goal of this research was to determine an empirical method of relating the droplet sizes and the spray patterns to the parameters and the geometries of the compound nozzles. Two different types of compound nozzles were studied, the compound silicon micro machined nozzle and the compound metal disk nozzle. Several different orifice geometries of each nozzle type were examined. The injector components upstream of the compound nozzle of two different types of injectors were also studied. A nondimensional characterization of the droplet sizes and the mass flow rates was proposed. The results of this study show that there exists optimum geometric features that will produce sprays with the minimum steady state and dynamic Sauter mean diameter. The spray of a compound nozzle can be characterized by the atomization efficiency and the discharge coefficient. Nozzle testing results show that many flow characteristics are developed in the compound nozzle.

The spray pattern of a fuel injector is a key factor in the mixing of the fuel with the air. One effective means of determining the fuel distribution in the spray is to collect the fuel in tubes, from various regions of the spray. The amount of fuel in the tubes is measured. These measurements are used to create diagrams and curves which graphically represent the fuel distribution within the spray. The term “Patternator” has come to mean a device which determines the spray distribution, in the sense that the device determines the pattern of the spray. The objective of this paper is to describe the operation, features, and performance of an automated patternator designed and built at Michigan Technological University for Ford Motor Company. The patternator system was constructed for rapid determination of the spray pattern in order to expedite the development of automotive port fuel injectors.

The objective of this project is to establish the feasibility of measuring the thickness of a thin dynamic liquid film using internally reflected light. The principle of the sensor operation is demonstrated through static calibration curves. The influence of various liquids is also explored by testing water, motor oil, Stoddard fluid, and finally skim milk to show the effect of a semi-opaque liquid. The response of the system to 1.25 millisecond impulse of light caused by a 500 Hz square wave is examined to demonstrate the dynamic range of the device. A wave machine is used to demonstrate the dynamic response of the sensor. These measurements are made with the early version of the film thickness sensor.

This project is intended to characterize the transient spray from a high pressure swirl injector. The spray regions were identified as the leading edge, cone, trailing edge, and vortex cloud. Each region was influenced somewhat differently by changes in the operational parameters. Increasing the ambient chamber pressure increased the droplet size in all regions of the spray. Increasing the fluid pressure reduced the droplet size in all regions of the spray, except for the vortex cloud. Increasing the swirl of the fluid leaving the fuel injector increased the size of the droplets in the leading edge and cone region.

An analogy is presented which describes the similarity between atomization and vaporization based on the conservation of energy. Many of the classic principles of ideal vaporization are shown to apply equally well to ideal atomization. The analogy provides a basis to evaluate atomization processes, systems involving atomization, and efficiencies of atomization devices. An example presents the calculation of various atomization parameters, including atomization efficiency.

An experimental technique was used in evaluating the influence of mixture preparation in the intake port on the performance of a steady-operating, 1.9L Ford engine. The fuel preparation components investigated in this study were vapor, droplets, and liquid streams. Engine performance was evaluated in terms of in-cylinder pressure and exhaust gas emissions. Fuel vapor, small droplets (Sauter mean diameter less than 10 mm), and liquid streams were produced and varied in a carefully-controlled mixture preparation system, which delivered an air/fuel mixture to an engine test cylinder. The air/fuel mixture was saturated prior to delivery to the cylinder so as to stabilize the fuel preparation components for study. Also, incorporated in the preparation system were devices for physically measuring the amount of fuel in the form of droplets and liquid streams.

Up to 80 percent of the total hydrocarbons emitted during the EPA Federal emissions test are produced in the first five minutes of this procedure. It has been theorized that this is in part due to wall wetting of the intake port and cylinder. This study measures the behavior of the fuel film thickness in the intake port during cold starting, steady state and transient operation. Three injector spray patterns with varying droplet sizes were utilized for the tests. The fuel film thickness in the intake port of a Ford 1.9L engine was measured using optical sensors. It was found that the spray pattern and droplet size affected the port wall wetting characteristics.

The feasibility of using kerosene fuel in a spark ignited two-stroke engine was investigated. Primary effort was directed at comparing kerosene fueled performance to gasoline fueled performance and to overcoming cold starting problems with kerosene. The single cylinder research engine had fuel injection upstream of the reed valve and used loop scavenging. A vortex pneumatic atomizer was used to reduced the droplet size. The results of this study indicate that the vortex pneumatic atomizer helps reduce poor performance of the engine when using kerosene fuel. A method to overcome the cold starting problem with kerosene fuel has been developed, which involves heating the atomization air during start up.

Lean limit characteristics of a pneumatic port fuel injection system is compared to a conventional port fuel injection system. The lean limit was based on the measured peak pressure. Those cycles with peak pressures greater than 105 % of the peak pressure for a nonfiring cycle were counted. Experimental data suggests that there are differences in lean limit characteristics between the two systems studied, indicating that fuel preparation processes in these systems influence the lean limit behaviors. Lean limits are generally richer for pneumatic fuel injection than those for conventional fuel injection. At richer fuel-to-air ratios the pneumatic injector usually resulted in higher torques. A simple model to estimate the evaporation occurring in the inlet manifold provided an explanation for the observed data.

A simple geometry pneumatic atomizer which could be used on internal combustion engine was tested with water as the working fluid. The pneumatic atomizer consists of a cylindrical chamber with an orifice plate at the outlet end. Liquid flows down the chamber walls and onto the nozzle orifice plate as a film. Air flows down the center of the chamber. The interaction of the air and water, which occurs at the orifice, atomizes the water. Large droplets form near the nozzle orifice and break up as they go down stream. Variations in the droplet size occurred in the spray. When geometry and flow rates were varied, changes which decreased the water film thickness or increased the air velocity at the nozzle orifice yielded smaller droplets in the spray. Droplet size data was measured by Malvern Laser Particle Sizer.

In the search for a way of increasing fuel economy and reducing hydrocarbon emissions of two-stroke-cycle loop-scavenged engines, investigations have been underway to evaluate various aspects of the digital engine concept. A two-stroke-cycle, loop-scavenged single cylinder engine was modified by replacing the head with a head having three subchambers and incorporating a distributing pump fuel injection system. The fuel injection system allowed one subcharaber to be operated at a time. The quantum combustion system demonstrated both lower fuel consumption and lower hydrocarbon emissions than a conventional homogeneous charge engine. The experimental evidence also indicates that the combustion essentially occurred in the one chamber into which fuel was injected. This work demonstrated the feasibilility of establishing stratified charge combustion by mechanically separating the regions of air from the regions of air/fuel mixtures by means of subchambers.

The digital engine concept uses direct injection into cavities or subdivisions of the combustion chamber. The subchambers trap fixed quantities of air and the appropriate amount fuel is then either injected or not injected into the subchambers. One of the advantages of this approach to fuel management is that the fuel injection system can be simplified since it is only required to inject one quantum of fuel. The results presented are for a prototype quantum injection system which uses a high pressure source of hydraulic fluid. Experimentation with this system has demonstrated most of the fundamental operation. However, additional work is required before the system is ready to be installed on a digital engine.

In most conventional engines the fuel supply system attempts to distribute equal amounts of fuel to each cylinder in any quantity between idle and maximum. The digital engine concept is an alternative fuel management system in which the fuel is delivered to the combustion chambers in quantums. This is accomplished by having multiple digital fuel injectors in each combustion chamber. Each injector when activated delivers a fixed amount of fuel or when deactivated it delivers none. The fuel delivery level is established by the selection of injectors which are activated. The most appropriate configuration for a digital engine is a two stroke loop scavenged stratified charge two stroke engine. The strategy for controlling the fuel delivery and the expected benefits of a digital engine are discussed.

The First Annual Blizzard Baja was hosted by Michigan Technological University's SAE Student Branch on February 7, 1981. This was a competition between student designed vehicles which had previously competed in summer Baja events. The Blizzard Baja consisted of a one hour endurance race run on ice and snow. The purpose was to provide the student engineers an opportunity to test their vehicles in cold weather, snow and icy conditions.