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Browsing by Author "Meroney, Robert N., committee member"

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    Applications of field programmable gate arrays for engine control
    (Colorado State University. Libraries, 2012) Viele, Matthew, author; Willson, Bryan D., advisor; Marchese, Anthony J., committee member; Meroney, Robert N., committee member; Troxell, Wade O., committee member
    Automotive engine control is becoming increasingly complex due to the drivers of emissions, fuel economy, and fault detection. Research in to new engine concepts is often limited by the ability to control combustion. Traditional engine-targeted micro controllers have proven difficult for the typical engine researchers to use and inflexible for advanced concept engines. With the advent of Field Programmable Gate Array (FPGA) based engine control system, many of these impediments to research have been lowered. This dissertation will talk about three stages of FPGA engine controller application. The most basic and widely distributed is the FPGA as an I/O coprocessor, tracking engine position and performing other timing critical low-level tasks. A later application of FPGAs is the use of microsecond loop rates to introduce feedback control on the crank angle degree level. Lastly, the development of custom real-time computing machines to tackle complex engine control problems is presented. This document is a collection of papers and patents that pertain to the use of FPGAs for the above tasks. Each task is prefixed with a prologue section to give the history of the topic and context of the paper in the larger scope of FPGA based engine control. The author of this study founded, built up, and eventually sold Drivven Inc., a company dedicated to the implementation of FPGAs in engine control. As a result, this study spans a decade of time where we see the first few papers related to FPGA based engine control, and concludes with FPGA based engine controllers being the de facto standard for advanced combustion research.
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    Cavitation damage scale effects: sudden enlargements
    (Colorado State University. Libraries, 1975) Stripling, Travis Earl, author; Tullis, J. Paul, advisor; Olson, H. G., committee member; Meroney, Robert N., committee member; Ball, James W., committee member
    The present study was aimed at investigating the cavitation damage downstream from sudden enlargement energy dissipators. Tests were conducted on geometrically similar circular orifices of five different orifice to pipe diameter ratios in three different pipe sizes of: 3-, 6-, and 12-inches. Highly polished 1100-0 aluminum specimens were mounted in the downstream pipe wall to detect the cavitation damage. Two different stages or levels of cavitation damage were defined for study: (1) "incipient damage" level based upon maintaining a maximum pitting rate of 1 pit/in.2/min. on 1100-0 aluminum, (2) cavitation damage regime where the maximum pitting rate was greater than 1 pit/in.2/min. Previously defined incipient damage scaling equations based upon damage data taken in the 3-in. pipe accurately predicted the incipient damage condition in the 6- and 12-in. pipes. Pressure scale effects on the incipient damage condition were constant for all pipe sizes tested. There were no size scale effects found for the incipient damage condition based upon maintaining a maximum pitting rate of 1 pit/in.2/min. The incipient damage condition was investigated in greater detail by studying the variation in the volume of the damage pits in the soft aluminum. The volume of the damage pit was related to the energy expended in format ion of the pit which was assumed to be a measure of the intensity of the cavitation impact blow forming the pit. It was found that at the incipient damage condition the intensity of cavitation impact blows varied with pipe size and orifice to pipe diameter ratio. The damage in the cavitation damage regime was found to be a function of both cavitation pitting rate and intensity of cavitation impact blows (energy of pit formation). A cavitation intensity parameter, defined as the product of cavitation pitting rate and energy of pit formation, was used to measure cavitation damage. Data was presented to show the general variation of cavitation intensity under conditions of varying cavitation index, varying upstream pressure, and varying pipe size. In addition, the cavitation damage scaling evaluations introduced by Thiruvengadam were used along with experimentally measured flow field data to predict variations in cavitation pitting rate and intensity of impact blows. The experimental results indicate that it is impossible to simulate total prototype cavitation loading conditions in terms of both cavitation pitting rate and intensity of impact blows in a hydraulic model of reduced size. An example is introduced demonstrating this fact. An alternative method using the cavitation intensity parameter is proposed for modeling prototype cavitation loading conditions in a model of reduced size.
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    Coupling an urban parameterization to an atmospheric model using an operational configuration
    (Colorado State University. Libraries, 2010) Nobis, Timothy E., author; Pielke, Roger A., advisor; Collett, Jeffrey L., committee member; Johnson, Richard H. (Richard Harlan), committee member; Meroney, Robert N., committee member
    Operational weather centers use numerical weather prediction (NWP) models to provide forecast weather guidance. Output from these models are then used to drive non-weather decision aids such as air quality forecast or dispersion models which are sensitive to near surface weather and very important in urban areas. While NWP models are usually run at resolutions fine enough to allow them to account for mesoscale flow systems (e.g. sea breeze), they are not designed to explicitly model an urban heat island (UHI) response. Other studies have shown that the UHI can interact with and alter local mesoscale flow systems in and around urban areas. This study examines the ability of an urban parameterization to improve operational NWP characterization of the sensible weather in Washington, DC on three separate days. The urban parameterization does seemly function in a subjective fashion to create many of the typical UHI features in spite of being run at a much coarser resolution than typically used with urban parameterization studies. When compared to actual near surface temperature data, while the parameterization was found to significantly underestimate the strength of the UHI (likely a product of the resolution), it does act to reduce the forecast temperature error in the District, especially when compared against an available vertical temperature profile. The parameterization did perform more ambiguously in the transition area between the suburban and rural regions where it seems the resolution was not high enough to model the often observed sharp transition between urban and rural environment. Overall, the presence of an urban parameterization seemed to improve the model's characterization of the near surface environment around Washington, DC.
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    Current distribution and particle motion in a barbed plate electrostatic precipitator
    (Colorado State University. Libraries, 1993) McKinney, Peter J., author; Davidson, Jane H., advisor; Gessler, Johannes, committee member; Wilbur, Paul J., committee member; Meroney, Robert N., committee member
    Electrohydrodynamic theory suggests that a modification in electrode geometry is a method of creating more favorable electrical and flow conditions in electrostatic precipitators. A novel barbed plate precipitator is designed to provide a more uniform current density distribution and electric field in the inter-electrode gap. Ground plate current densities of both a conventional wire-plate precipitator and the optimized barbed plate precipitator are compared. Particle motion is observed via a laser light-sheet and measured with a laser Doppler anemometer. Streamwise and transverse mean and fluctuating particle velocities, particle motion length scales and diffusivities are measured at electrical and flow conditions typical of industrial precipitators. Ground plate particle collection patterns are photographed. Results show a hexagonal arrangement of barbs provides a more uniform current density distribution and electric field than exist in the wire-plate geometry. Additionally, the barbed plate creates a stronger electric field throughout most of the inter-electrode space and therefore generates higher particle drift velocities. However, the barbed plate increases the magnitude of the electrically generated turbulence. Length scales are of the same order in the two geometries even though the electrode spacing of the barbed plate is double that of the wire-plate precipitator. From an electrical standpoint, the barbed plate design is superior to the wire-plate precipitator. The more uniform distribution of current and electric field coupled with higher levels of mixing suggest the barbed plate may be most suitable for use as a precharger in the entrance section of a parallel plate precipitator.
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    Electrohydrodynamic flow in a barbed plate electrostatic precipitator
    (Colorado State University. Libraries, 1988) McKinney, Peter J., author; Davidson, Jane H., advisor; Wilbur, Paul J., committee member; Sandborn, Virgil A., committee member; Meroney, Robert N., committee member
    The large scale secondary flows and turbulence induced by the inhomogeneous negative corona discharge in the conventional wire-plate precipitator are known to reduce collection efficiencies, particularly in applications with high mass loadings of fine particulates. Electrohydrodynamic theory suggests that a modification in electrode geometry is necessary to control the electrically induced flow. A plate-plate precipitator using a barbed plate discharge electrode is designed to provide a more uniform current density distribution. Electrical and fluid dynamic characteristics of four model barbed plate electrodes, with varying plate-to-plate and barb spacing, are evaluated and compared to characteristics of a laboratory wire-plate precipitator in a specially designed wind tunnel facility. Current voltage characteristics of each electrode are presented and the visual appearance of the corona discharge discussed. Hot-film anemometer measurements of the turbulent flow field downstream of the active precipitator include mean and turbulence intensity profiles, as well as spectral analysis of the flow. Gas eddy diffusivities are estimated from integral length scale calculations. A laser light sheet is used to visualize the flow in the inter-electrode space. Results show that the electrical characteristics of the planar electrodes are well within the range needed for industrial precipitation and that the scale of the current in homogeneities within the precipitator are reduced. Fluid dynamic measurements confirm that electrode geometry has a significant effect on the electrohydrodynamic turbulence production. Turbulence intensity data indicate that the point discharges in the planar geometry cause higher turbulence levels than the wire discharges. Turbulent diffusivites are correspondingly higher in the planar geometry. These results indicate that mixing may actually be enhanced in the suggested design. Flow field measurements made downstream of the precipitator may not however be representative of the electrically induced flow within the precipitator. Plate end effects observed in the visualization procedure may have a significant effect on the downstream flow and bias the measurements. Additional study is necessary to determine if the planar geometry is a viable design. The most important test of any new precipitation design is measurement of its particle collection efficiency.