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A system was developed which provides nutrients and water to plants while maintaining good aeration at the roots and preventing water from escaping in reduced gravity. The nutrient solution is circulated through porous tubes under negative pressure and moves through the tube wall via capillary forces into the rooting matrix, establishing a non-saturated condition in the root zone. Tests using prototypes of the porous tube water and nutrient delivery system indicate that plant productivity in this system is equivalent to standard soil and solution culture growing procedures. The system has functioned successfully in short-term microgravity during parabolic flight tests and will be flown on the space shuttle. Plants are one of the components of a bioregenerative life support system required for long duration space missions.

The flow through diesel fuel injector nozzles is important because of the effects on the spray and the atomization process. Modeling this nozzle flow is complicated by the presence of cavitation inside the nozzles. This investigation uses a two-dimensional, two-phase, transient model of cavitating nozzle flow to observe the individual effects of several nozzle parameters. The injection pressure is varied, as well as several geometric parameters. Results are presented for a range of rounded inlets, from r/D of 1/40 to 1/4. Similarly, results for a range of L/D from 2 to 8 are presented. Finally, the angle of the corner is varied from 50° to 150°. An axisymmetric injector tip is also simulated in order to observe the effects of upstream geometry on the nozzle flow. The injector tip calculations show that the upstream geometry has a small influence on the nozzle flow. The results demonstrate the model's ability to predict cavitating nozzle flow in several different geometries.

This Paper introduces a modular, flexible and user-friendly dynamic powertrain model of the US Army's High Mobility Multi-Wheeled Vehicle (HMMWV). It includes the DDC 6.5L diesel engine, Hydra-matic 4L80-E automatic transmission, Torsen differentials, transfer case, and flexible drive and axle shafts. This model is used in a case study on transmission optimization design to demonstrate an application of the model. This study shows how combined optimization of the transmission hardware (clutch capacity) and control strategy (shift time) can be explored, and how the models can help the designer understand dynamic interactions as well as provide useful design guidance early in the system design phase.

The objective of this study was to investigate the effects of fuel viscosity and the effects of nozzle inlet configuration on the characteristics of high injection pressure sprays. Three different viscosity fuels were used to reveal the effects of viscosity on the spray characteristics. The effects of nozzle inlet configuration on spray characteristics were studied using two mini-sac six-hole nozzles with different inlet configurations. A common rail injection system was used to introduce the spray at 90 MPa injection pressure into a constant volume chamber pressurized with argon gas. The information on high pressure transient sprays was captured by a high speed movie camera synchronized with a pulsed copper vapor laser. The images were analyzed to obtain the spray characteristics which include spray tip penetration, spray cone angle at two different regions, and overall spray Sauter Mean Diameter (SMD).

A new technique which is based on optoacoustic phenomena has been developed for measuring in-cylinder gas temperature and turbulent diffusivity. In the experiments, a high energy Nd:YAG pulsed laser beam was focused to cause local ionization of air at a point in the combustion chamber. This initiates a shock wave and creates a hot spot. The local temperature and turbulent diffusivity are determined by monitoring the shock propagation and the hot spot growth, respectively, with a schlieren photography system. In order to assess the validity and accuracy of the measurements, the technique was also applied to a turbulent jet. The temperature measurements were found to be accurate to within 3%. Results from the turbulent jet measurements also showed that the growth rate of the hot spot diameter can be used to estimate the turbulent diffusivity. In-cylinder gas temperature measurements were made in a motored single cylinder Caterpillar diesel engine, modified for optical access.

Fundamental simulations using DNS type procedures were used to investigate the ignition, combustion characteristics and the lift-off trends of a spatially evolving turbulent liquid fuel jet. In particular, the spatially evolving n-Heptane spray injected in a two-dimensional rectangular domain with an engine like environment was investigated. The computational results were compared to the experimental observations from an optical engine as reported in the literature. It was found that an initial fuel rich combustion downstream of the spray tip is followed by diffusion combustion. Investigations were also made to understand the effects of injection velocity, ambient temperature and the droplet radius on the lift-off length. For each of these parameters three different values in a given range were chosen. For both injection velocity and droplet radius, an increase resulted in a near linear increase in the lift-off length.

Two soot-containing turbulent non-premixed flames burning gaseous acetylene in atmospheric-pressure air were investigated by conducting non-intrusive optical experiments at various flame locations. The differences in burner exit Reynolds numbers of these flames were large enough to examine the influence of flow dynamics on soot formation and evolution processes in heavily-sooting flames. By accounting for the fractal nature of aggregated primary particles (spherules), the proper interpretation of the laser scattering and extinction measurements yielded all the soot parameters of principal interest. With the separation of spherule and aggregate sizes, the axial zones of the prevailing turbulent soot mechanisms were accurately identified. With the high propensity of acetylene fuel to soot, relatively fast particle nucleation process led to high concentrations immediately above the burner exit.

The ASTROCULTURE™ (ASC) middeck flight experiment series was developed to test and integrate subsystems required to grow plants in reduced gravity, with the goal of developing a plant growth unit suitable for conducting quality biological research in microgravity. Flights on the Space Shuttle have demonstrated control of water movement through a particulate rooting material, growth chamber temperature and humidity control, LED lighting systems and control, recycling of recovered condensate, ethylene scrubbing, and carbon dioxide control. A complete plant growth unit was tested on STS-63 in February 1995, the first ASC flight in which plant biology experiments were conducted in microgravity. The methods and objectives used for control of environmental conditions in the ASC unit are described in this paper.

Using a low-speed high-torque (LSHT) pump/motor to provide the speed range and torque for a hydrostatic automobile offers a number of advantages over using a high-speed low-torque pump/motor, combined with a gear reducer. However, there appear to be no LSHT units commercially available that have true variable displacement capability. Because of this void, a variable displacement pump/motor has been designed and built that could provide a direct drive for each wheel of a hydrostatic automobile. The unit uses some components such as the cylinder block, piston and modified rotating case from a commercially available radial piston pump/motor. Initial preliminary testing of the pump/motor indicates that it has good efficiency and performance characteristics, and, with further development should be very attractive for automotive use. This paper focuses on the design and kinematics of the device.

An investigation of several diesel injector nozzles that produced different engine emissions performance was performed. The nozzle styles used were two VCO type nozzles that were manufactured using two different techniques, and two mini-sac nozzles that provided comparison. Fired experiments were conducted on a Detroit Diesel Series 50 engine. Optical access was obtained by substituting a sapphire window for one exhaust valve. Under high speed, high load, retarded injection timing conditions, it was discovered that each nozzle produced different specific soot and NOx emissions. High-speed film images were obtained. It was discovered that the temperature and KL factor results from the 2-color optical pyrometry showed significant differences between the nozzles. The authors propose the possibility that differences in air entrainment, caused by potential differences in CD due to surface finish, may contribute to the variance in emissions performance.

Micro-machined planar orifice nozzles have been developed and used with commercially produced diesel injection systems. Such a system may have the capability to improve the spray characteristics in DI diesel engines. The availability of a MEMS (Micro-Electro-Mechanical-Systems) processing sequence supported the construction of micro-planar orifice nozzles, and micro-systems technology was also employed in our macro-instrumentation. To demonstrate this process, fourteen MEMS nozzles were fabricated with deep X-ray lithography and electroplating technology. The circular orifice diameters were varied from 40 to 260 microns and the number of orifices varied from one to 169. Three plates with non-circular orifices were also fabricated to examine the effect of orifice shape on spray characteristics. These nozzles were then attached to commercial injectors and the associated injection systems were used for the spray experiments.

We have developed and used micro-machined injector nozzles with commercially produced diesel injection systems that have the capability to improve the spray characteristics in DI diesel engines. The availability of a MEMS (Micro-Electro-Mechanical-Systems) processing sequence supported the construction of micro-diesel injector nozzles, and micro-systems technology was also employed in our macro-instrumentation. Fourteen different circular plates (nickel-iron alloy) were fabricated with deep X-ray lithography and electroplating technology. Five plates that have a single orifice were fabricated to investigate the effect of orifice diameter on spray characteristics; i.e., 40 to 260 microns. The spacing between multiple orifices was also varied; e.g., two plates that each had 41 orifices and 169 orifices, respectively, with a diameter of 40 microns. Finally, three plates with non-circular orifices were also made to examine the effect of orifice shape on spray characteristics.

A direct calibration has been performed on laser-induced fluorescence measurements of the oil film in a single cylinder air-cooled research engine by simultaneously measuring the minimum oil film thickness by the capacitance technique. At the minimum oil film thickness the capacitance technique provides an accurate measure of the ring-wall distance, and this value is used as a reference for the photomultiplier voltage, giving a calibration coefficient. This calibration coefficient directly accounts for the effect of temperature on the fluorescent properties of the constituents of the oil which are photoactive. The inability to accurately know the temperature of the oil has limited the utility of off-engine calibration techniques. Data are presented for the engine under motoring conditions at speeds from 800 - 2400 rpm and under varying throttle positions.

Fundamental simulations in a quiescent cell under adiabatic conditions were made to understand the effect of temperature, equivalence ratio and the components of the recirculated exhaust gas, viz., CO2 and H2O, on the combustion of n-Heptane. Simulations were made in single phase in which evaporated n-Heptane was uniformly distributed in the domain. Computations were made for two different temperatures and four different EGR levels. CO2 or H2O or N2was used as EGR. It was found that the initiation of the main combustion process was primarily determined by two competing factors, i.e., the amount of initial OH concentration in the domain and the specific heat of the mixture. Further, initial OH concentration can be controlled by the manipulating the ambient temperature in the domain, and the specific heat capacity of the mixture via the mixture composition. In addition to these, the pre combustion and the subsequent post combustion can also be controlled via the equivalence ratio.

An emissions and performance study was performed to show the effects of injection pressure, nozzle hole inlet condition (sharp and rounded edge) and nozzle included spray angle on particulate, NOx, and BSFC. The tests were conducted on a fully instrumented single-cylinder version of the Caterpillar 3406 heavy duty engine at 75% and 25% load at 1600 RPM. The fuel system consisted of an electronically controlled, hydraulically actuated, unit injector capable of injection pressures up to 160 MPa. Particulate versus NOx trade-off curves were generated for each case by varying the injection timing. The 75% load results showed the expected decrease in particulate and flattening of the trade-off curve with increased injection pressure. However, in going from 90 to 160 MPa, the timing had to be retarded to maintain the same NOx level, and this resulted in a 1 to 2% increase in BSFC. The rounded edged nozzles were found to have an increased discharge coefficient.

A study was performed to correlate the Sauter Mean Diameter (SMD), NOx and particulate emissions of a direct injection diesel engine with various injection pressures and different nozzle geometry. The spray experiments and engine emission tests were conducted in parallel using the same fuel injection system and same operating conditions. With high speed photography and digital image analysis, a light extinction technique was used to obtain the spray characteristics which included spray tip penetration length, spray angle, and overall average SMD for the entire spray. The NOx and particulate emissions were acquired by running the tests on a fully instrumented Caterpillar 3406 heavy duty engine. Experimental results showed that for higher injection pressures, a smaller SMD was observed, i.e. a finer spray was obtained. For this case, a higher NOx and lower particulate resulted.

In the current investigation, the authors identified conditions under which increased in-cylinder turbulence can be used to improve diesel emissions. Two separate regimes of engine operation were identified; one in which combustion was constrained by mixing and one in which it was not. These regimes were dubbed under-mixed and over-mixed, respectively. It was found that increasing mixing in the former regime had a profound effect on soot emission. Fuel injection characteristics were found to be extremely important in determining the point at which mixing became inadequate. In addition, the ratio of the fuel injection momentum flux relative to that of the gas injection was found to be important in determining how increasing mixing would effect soot emissions.

Forage harvesting, processing and handling equipment research is currently underway which will improve commodity quality, produce “value -added” products from forages, reduce energy and labor requirements of the equipment and improve forage marketability. Technologies are described which could increase forage quality and value by removing it from the field sooner after it is mowed to minimize the risk of weather damage. Mechanisms and management strategies for reducing the labor and energy required for field processing and for improving the marketability of forages are also described.

Transient operation of automobile engines is known to contribute significantly to regulated exhaust emissions, and is also an area of drivability concerns. Furthermore, many on-board diagnostic algorithms do not perform well during transient operation and are often temporarily disabled to avoid problems. The inability to quickly and repeatedly test engines during transient conditions in a laboratory setting limits researchers and development engineers ability to produce more effective and robust algorithms to lower vehicle emissions. To meet this need, members of the Powertrain Control Research Laboratory (PCRL) at the University of Wisconsin-Madison have developed a high-bandwidth, hydrostatic dynamometer system that will enable researchers to explore transient characteristics of engines and powertrains in the laboratory.

High-resolution planar laser-induced fluorescence (PLIF) measurements were performed on the scalar field in an optical engine. The measurements were of sufficient resolution to fully resolve all of the length scales of the flow field through the full cycle. The scalar dissipation spectrum was calculated, and by fitting the results to a model turbulent spectrum the Batchelor scale of the turbulent flow was estimated. The scalar inhomogeneity was introduced by a low-momentum gas jet injection. A consistent trend was observed in all data; the Batchelor scale showed a minimum value at top dead center (TDC) and was nearly symmetric about TDC. Increasing the engine speed resulted in a decrease of the Batchelor scale, and the presence of a shroud on the intake valve, which increased the turbulence intensity, also reduced the Batchelor scale. The effect of the shrouded valve was less significant compared to the effect of engine speed.