Fire Protection Engineering Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/2772

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End date: 2009Subject: search.filters.subject.Engineering, General

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    Analysis of Underventilated Compartment Fires
    (2009) Wolfe, Andrew John; Mowrer, Frederick; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Little research has been done to examine full-scale unventilated fires despite their common occurrence and relevance. This project was conducted to characterize the fire dynamics of unventilated and partially ventilated compartment fires. A series of fifteen full-scale fires were performed within an instrumented, four room, apartment style enclosure measuring 41.8 m2 (450 ft2). Three different fuel sources, including sofas, kitchen cabinets, and cotton batting, were tested using different ventilation and ignition schemes to analyze the effect of ventilation on fire growth and tenability. The results of these tests allowed for the examination of the effects of ventilation on: general fire dynamics, including fire growth, smoke and gas production, and vitiation; tenability factors including temperature, heat flux and carbon monoxide FED levels; and the ability to utilize forensic tools to determine the cause and progression of a fire.
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    CHARACTERIZATION OF THE INITIAL SPRAY FROM A JET IN CROSSFLOW
    (2009) Zheng, Yinghui; Marshall, André; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    An experimental study on the initial spray from a liquid jet in air crossflow was conducted using Shadowgraphy and Particle Image Velocimetry (PIV) techniques. Momentum ratio and gas Weber number were varied to study their effects on the column trajectory, spray trajectory, breakup locations and spray characteristics after column breakup. Correlations for column trajectory, spray trajectory, breakup locations in terms of momentum ratio and gas Weber number were obtained using linear regression of the experimental data. Two breakup modes were recognized in the test (Column breakup and Bag breakup), a breakup mode regime map was provided including effects of momentum ratio and gas Weber number. Drop characteristics in the spray were also investigated.
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    SMOKE POINTS OF MICROGRAVITY AND NORMAL GRAVITY COFLOW DIFFUSION FLAMES
    (2009) Dotson, Keenan Thomas; Sunderland, Peter B; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Smoke points were measured in microgravity aboard the International Space Station (ISS) as part of the Smoke Points in Coflow Experiment (SPICE), and in normal gravity conditions. In microgravity conditions increasing the coflow velocity or decreasing the burner diameter increased the smoke point flame length. A simplified prediction of centerline jet velocity did not yield residence-time-based criticalities or data collapse. Simulation of non-reacting flows showed that the simplified centerline velocity prediction was able to predict velocity decay for only relatively weak coflows. An improved model may yield different results. In normal earth gravity coflow velocity exhibited mixed effects. For burner diameters of 0.41, 0.76, and 1.6 mm, smoke points increased with increases of coflow velocity. For an unconfined coflow burner with a burner diameter of 13.7 mm smoke point length decreased with increasing coflow velocity for ethylene and propylene, while increasing for propane flames.
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    PYROLYSIS MODEL PARAMETER OPTIMIZATION USING A CUSTOMIZED STOCHASTIC HILL-CLIMBER ALGORITHM AND BENCH SCALE FIRE TEST DATA
    (2009) Webster, Robert Dale; Trouvé, Arnaud C; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This study examines the ability of a stochastic hill-climber algorithm to develop an input parameter set to a finite difference one-dimensional model of transient conduction with pyrolysis to match experimentally determined mass loss rates of three sample materials exposed to a range of constant incident heat flux. The results of the stochastic hill-climber algorithm developed as part of the present study are compared to results obtained with genetic algorithms. Graphical documentation of the impact of single parameter mutation is provided. Critical analysis of the physical meaning of parameter sets, and their realistic range of application, is presented. Criteria are also suggested for stability and resolution of solid phase temperature and fuel mass loss rate in an implicit Crank-Nicolson scheme with explicit treatment of the heat generation source term.
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    Stream-wise Discharge Characteristics of Pendant Sprinkler Sprays
    (2009) Do, Chi Tran; Marshall, André W; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Detailed atomization measurements in actual sprinklers are needed for proper spray specification in suppression modeling and analysis. In basic pendant sprinkler configurations, the spray originates from two streams corresponding to flow deflected along the tines of the pendant and flow passing through the void spaces between the tines. In this study, measurements of flow splits (between space and tine streams), sheet breakup distances, drop size, and drop velocity measurements were performed over a range of sprinkler geometries and injection pressures to characterize the near-field sprinkler spray. These detailed measurements were used to support the development of scaling laws describing the effects of injector geometry and injection conditions on sprinkler discharge characteristics.
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    An Investigation of the UL-94V Plastics Flammability Test
    (2009) Downey, Brian Patrick; Quintiere, James G.; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The UL-94 Vertical Burning Flammability Test (UL-94V) is used to measure flammability characteristics of plastic materials. The results of the test allow for plastic materials to be separated into classification categories. These categories will be discussed and related to fire phenomena. Simulations of the test have allowed for the development of general flame height and heat flux correlations. We believe these are independent of the actual solid fuels. In addition, the heat flux from the ignition burner, a specified premixed flame, has been measured. These data provide the basis for assessing fire behavior of materials using their fire properties such as heat of combustion, heat of gasification, ignition temperature, and thermal properties. Criteria for ignition, sustained burning, and flame spread are determined. These outcomes are then related to the UL-94V classification categories. An analysis of melting is also considered in order to assess the flaming drip aspect of the test.
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    The Impact of Thermal Imaging Camera Display Quality on Fire Fighter Task Performance
    (2008) Rowe, Justin Lawrence; Mowrer, Frederick W.; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Thermal imaging cameras (TIC) have become a vital fire fighting tool for the first responder community but there are currently no standardized quality control regulations. The purpose of the study was to understand the impact of TIC display image quality on a fire fighter's ability to perform a hazard recognition task. Test subjects were asked to identify a fire hazard by observing infrared images. The image matrix considered the interactions of several image characteristics including contrast, brightness, spatial resolution, and noise. The results were used to create a model function to predict the effect of image quality on user performance. This model was recommended to be incorporated in image quality test methods in development at the National Institute of Standards and Technology. These recommendations will also be provided to the National Fire Protection Association for use in an upcoming standard on fire fighting TIC.
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    Modeling Energy Transport in Porcine Skin
    (2009) Keslin, Jeff Michael; di Marzo, Marino; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The ability to measure the burn depth in human skin is of great importance in identifying and successfully treating burn injuries. A non-invasive method for measuring this depth is described where a jet of cold air is impinged on the skin and the thermal and physiological response of the skin is observed. A computational model is developed to characterize the temperature response of the dead or burnt skin. This is validated using an experiment involving a jet impinging on a pig skin sample, with temperature measurements made by a non-invasive infrared thermocouple. This data can be used to create and compare a similar model with the inclusion of the physiological response that is present when the test is administered on live or partially burnt skin. Then a correlation may be developed that will predict the burn depth in the affected tissue.
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    Numerical modeling of full scale limited ventilation fire tests
    (2008) Boehmer, Haavard; Trouvé, Arnaud; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Underventilated enclosure fires represent one of the largest causes of fire fatalities and understanding their behavior is of great interest. The newest major release of the Fire Dynamics Simulator (FDS) has made significant progress towards providing a tool for accurate modeling of underventilated fire behavior. This study sought to evaluate the effectiveness of the extinction model and two-step combustion model in FDS version 5 by simulating full scale fire tests in an apartment setting with realistic furniture items using heat release rate data from furniture calorimeter and load cell. The extinction model provides a more accurate representation of the fire behavior in the compartment but the oxygen and temperature results are not satisfactory for severely underventilated fires. The effects of the enclosure causes heat release rate data from free-burn calorimeter tests to give a poor representation of the burning behavior of real furniture items in a compartment.
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    Smoke Characterization of Incipient Fire Sources for FDS Modeling
    (2008-08-29) Brookman, Matthew James; Mowrer, Frederick; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This thesis describes the experimental and analytical methods used to characterize the heat and smoke release rates of eight different incipient fire sources. These characterizations are part of a larger effort to evaluate the current smoke detection prediction capabilities of the Fire Dynamics Simulator (FDS) version 5.1.0. FDS is a computational fluid dynamics model of fire development based on the concept of large eddy simulation; the FDS model is under ongoing development at the Building and Fire Research Laboratory of the National Institute of Standards and Technology. The experimental aspect of this thesis includes developing a repeatable test protocol and characterizing each of the fuel sources. The experimental data produced from this phase is then input into FDS and the results of these simulations are compared to these experimental data. FDS has provided a range of accuracy near 5 % of the input values for smoke characteristics. The lag times associated with the output data can largely be attributed to the uncorrected experimental data. The time scaled inputs for FDS are based on the time that the instrumentation within the exhaust duct detected the smoke release from the material and the transport time required to move the smoke from the specimen to the instrumentation is not compensated for. Some variations in detection and data acquisition are expected.