Fire Protection Engineering Theses and Dissertations

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

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    CHARACTERIZING SMOKE DISPERSION ALONG BEAMED CEILINGS USING SALT-WATER MODELING
    (2010) Chan, Chau Siang; Marshall, Andre W.; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The study successfully validated the use of salt-water analog modeling as an effective diagnostic, predictive and scaling tool for understanding fire dispersion in a beam-ceiling complex compartment using the Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF) techniques. Dimensionless dispersion signatures and front arrival times were compared between the fire and salt-water experiments which showed excellent agreement. Prediction of the detector lag times using fire and saltwater data agreed with that of fire experiments.
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    EVALUATION OF THE THERMAL PERFORMANCE OF FIRE FIGHTER PROTECTIVE CLOTHING WITH THE ADDITION OF PHASE CHANGE MATERIAL
    (2010) McCarthy, Lee K.; di Marzo, Marino; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Fire fighters rely on fire fighter protective clothing (FFPC) to provide adequate protection in the various hazardous environments they may encounter during operations. FFPC has seen significant advancement in technology over the past few decades. The addition of phase change material (PCM) to FFPC is a new technology with potential to enhance the thermal protection provided by the FFPC. To explore this technology, data from bench-scale experiments involving FFPC with PCMs are compared with a theoretical finite difference heat transfer model. The results demonstrate an effective method to mathematically model the heat transfer and provide insight into the effectiveness of improving the thermal protection of FFPC. The experiments confirm that the latent heat absorbed during the phase change reduces temperatures that might be experienced at the fire fighter's skin surface, advancing the high temperature performance of FFPC.
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    Spray Characteristics From Fire Hose Nozzles
    (2010) Salyers, Brian Edward; Marshall, Andrew W; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This research examines the spray characteristics of fire hose streams. Smooth bore fire hose nozzles create jets with shear column breakup due to high Weber numbers. Laboratory settings produced a cylindrical water jet with the same column breakup behavior. The jet was injected into still air with fully developed turbulent flow. The test nozzle was oriented parallel to the floor. A patternator defined the shape and distribution of the spray. Shadowgraphy measurements determined the flow, drop size and velocity. The spray was tested in the middle of the liquid core.
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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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    Wind-Driven Plume Dispersion Near A Building
    (2008-05-05) Ling, Young Ern; Marshall, Andre W; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The dispersions of smoke or hazardous materials during accidental releases are of concern in many practical applications. A technique combining salt-water modeling and Particle Image Velocimetry (PIV) is developed to study the dispersion of a buoyant plume in a complex configuration. Salt-water modeling based on the analogy between salt-water flow and fire induced flow has proven to be a successful method for the qualitative analysis of fire induced plumes. With the use of PIV, detailed measurements of the velocity field can be taken for quantitative analysis of the plume behavior. The technique is first validated for a canonical unconfined plume scenario by comparing the results with theory and previous experimental data, and subsequently extended to qualitatively and quantitatively analyze plume dispersion in a crossflow with the construction of a crossflow generation system for the salt-water modeling facility. Lastly, plume dispersion in a crossflow near a building is analyzed.
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    Energy Transport in Firefighter Protective Clothing
    (2008-01-24) Spangler, Kevin B; di Marzo, Marino; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Firefighting protective clothing is a highly advanced system designed to protect people from being burned in high temperature environments. Studies have shown a time delay from when a firefighter enters a high temperature environment until the skin feels a temperature increase. A similar time delay is found when the firefighter leaves the hot environment until the skin begins to cool. An experiment was conducted that used thermocouples to observe room temperatures, outside gear temperatures and skin temperatures of firefighters in high intensity and long duration heat exposures. Computer models were created to duplicate and understand the resulting temperature response in the tests. A multi-layered model uses defined material properties to replicate the results and understand the contribution of the individual layers. The computer models can recreate the testing results and it is found that air gaps throughout firefighter gear are critical in providing protection from heat for the firefighters.
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    Analysis of the initial spray from canonical fire suppression nozzles
    (2007-08-10) Ren, Ning; Marshall, André W; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The performance of a fire suppression spray is governed by injector discharge characteristics. An atomization model based on the theoretical evolution of a radially expanding sheet generated by an impinging jet has been established in this study. The atomization model predicts characteristic initial drop location, size, and velocity based on injector operating conditions and geometry. These model predictions have been compared with measured discharge characteristics from three nozzle configurations of increasing geometrical complexity over a range of operating conditions. Differences between the predicted and measured initial spray are critically evaluated based on the experimentally observed atomization behavior.
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    Numerical Simulation of Ignition and Transient Combustion in Fuel Vapor Clouds
    (2007-07-31) Wiley, Jennifer; Trouvé, Arnaud; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The Large-Eddy Simulation (LES) approach is used to model partially-premixed combustion (PPC) in confined and unconfined fuel vapor clouds. The model is based on the concept of a filtered reaction progress variable to describe the premixed combustion. The premixed combustion model is implemented into the Fire Dynamics Simulator (FDS), developed at the National Institute of Standards and Technology, USA, and is coupled with either an equilibrium-chemistry, mixture-fraction based model (FDS Version 4) or an eddy dissipation model (FDS Version 5) for non-premixed combustion. Modifications to the model are developed and implemented with the goal of reducing the grid resolution requirement while still producing physically sound results. The modified formulation is tested using both versions of the non-premixed combustion model, and the results are compared. It is found that the modifications are capable of reducing errors associated with poorly-resolved simulations in both versions of the model.