Fire Protection Engineering Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2772
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Item A REDESIGN OF THE EXHAUST AND GAS SAMPLING SYSTEM OF THE FIRE PROPAGATION APPARATUS(2022) Roy, Shuvam; Stoliarov, Stanislav; Raffan-Montoya, Fernando; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Standard bench scale fire apparatuses are useful tools to perform repeatable and reproducible firetests that acquire key fire properties, such as heat release rate and time to ignition, for materials in a cost-effective manner. The Fire Propagation Apparatus (FPA) is one of the only standard bench scale apparatuses that has the ability to acquire these key fire properties in a controlled environment setting. However, the design of the apparatus is quite complex. In this work, the exhaust and gas sampling system designs were redesigned and constructed to increase modularity and manufacturability, adapt to the University of Maryland’s Department of Fire Protection Engineering laboratory settings, and provide greater ease for the end user operations. After the construction of the FPA systems, tests were conducted to verify the accuracy of the measurement devices. Equations for the calculation of heat release rate from FPA sensor data were derived and used for a series of combustion experiments. These equations were compared to the ones provided in the standard to gain insight on their systematic differences.Item Strategies for Improved Fire Detection Response Times in Aircraft Cargo Compartments(2020) Wood, Jennifer Marie; Milke, James A.; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Prompt fire detection in cargo compartments on board transport aircraft is an important safety feature. Concern has been expressed for the activation time of contemporary detection technologies installed on aircraft. This project will deliver a continuation of research on the issues that have been identified relative to fire detection improvements in cargo compartments on aircraft, with a particular emphasis on freighters. Gas sensors and dual wavelength detectors were demonstrated in a previous phase to be responsive to fires in the previous experiment program. Detectors placed inside a Unit Loading Device (ULD) responded quickly to the array of fire sources. Thus, a further exploration of these observations is conducted including wireless technology along with an analysis of the effects of leakage rates on fire signatures inside ULDs. One primary goal is to assess the differences in fire detection time for detectors located within ULD versus those located on the ceiling of the cargo compartment for fires which originate in a ULD. The results indicated the detector location with the shortest activation time is inside of the ULD. Within the ULD, the wireless detector outperformed both air sampling detectors, however, the results could vary if threshold levels were more restrictive.Item VERIFICATION TESTS OF MASS CONSERVATION FOR FIREFOAM AND DEVELOPMENT OF A USER'S GUIDE(2019) Wu, Shiyun; Trouvé, Arnaud; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The objective of this study is to develop basic verification tests for FireFOAM, a large eddy simulation (LES) solver developed by FM Global for fire applications, and based on the general-purpose Computational Fluid Dynamics (CFD) solver called OpenFOAM. These tests will be eventually included in an upcoming User Guide for FireFOAM users. We focus here on a series of tests developed to evaluate global species mass conservation statements. The series includes a two-dimensional helium plume case, a three-dimensional helium plume case and a three-dimensional pool fire case. The two-dimensional helium plume case focuses on the effects of changing the temporal discretization scheme in FireFOAM. The three-dimensional helium plume case focuses on the effects of changing the spatial discretization scheme used to describe the convection terms in the governing equations. Finally, the three-dimensional pool fire case focuses on the effects of changing the number of outer loops used to provide coupling between the governing equations that are solved sequentially. The results of the tests provide valuable insight for FireFOAM users who need to make numerical choices on the temporal discretization scheme, the spatial discretization scheme and the number of outer loops with little guidance on the impact of these choices.Item SIMPLIFIED STRUCTURAL DESIGN APPROACH FOR OPEN COMPARTMENTS IN THE CASE OF FIRE(2018) Nassiri, Parisa; Torero, Jose L.; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A vast majority of modern commercial and office buildings are designed to allow for maximum tenant flexibility. This results in a high demand for open floor plans and for versatility in compartmentation and architecture. The need for a thorough understanding of the behavior of a fire in such spaces is necessary for the improvement of codes and standards as well as for performance-based design. By considering the thermal properties of typical structural materials the energy equation is studied to establish if a simplified formulation of the thermal boundary condition can be used. The simplified formulation is defined by the characteristic heating time scales and the sensitivity of the structure to develop temperature gradients. Understanding the way in which a structure heats enables engineers to establish an adequate formulation of the fire. A series of full-scale large compartment fires were conducted in order to study the influence on fire behavior on open floor plan spaces in a project called ‘Real Fires for the Safe Design of Tall Buildings’. This work presents the results from some experiments of the series. The focus is to quantify the fire behavior in what pertains the performance assessment of structural elements. The main objective is to deliver a simplified design approach based on a detailed analysis of the data. Analysis shows that simplifications can be made for boundary conditions and temperature evolution inside materials in specific conditions.Item A Generalized Model for Wall Flame Heat Flux During Upward Flame Spread on Polymers(2015) Korver, Kevin; Stoliarov, Stanislav; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A current model accurately predicts flame to surface heat flux during upward flame spread on PMMA based on a single input parameter, the mass loss rate. In this study, the model was generalized to predict the heat flux for a broad range of polymers by adding the heat of combustion as a second input parameter. Experimental measurements were conducted to determine mass loss rate during upward flame spread and heat of combustion for seven different polymers. Four types of heat of combustion values were compared to determine which generated the most accurate model predictions. The complete heat of combustion yielded the most accurate predictions (± 4 kW/m2 on average) in the generalized model when compared to experimental heat flux measurements collected in this study. Flame heat flux predictions from FDS direct numerical simulations were also compared to the generalized model predictions in an exploratory manner and found to be similar.Item Fire Hazard of the Contemporary American Home(2014) Hanson, Robert E.; Milke, James A; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Annual direct property damage for one- and two- family residential fires is estimated as $5.9 billion in the United States. Recent research has suggested that the level of fire hazard in contemporary homes is greater than legacy homes. This study utilizes national fire incident data from 2003 to 2010 to examine trends and characteristics of residential fires. The Item First Ignited and Heat Source for fires are analyzed in a risk model. Structural Member is the Item First Ignited that contributes the greatest amount of risk in one- and two- family houses. The Heat Source for Structural Member is concentrated among three main categories: Operating Equipment, Electrical Arcing, and Hot or Smoldering Objects. Grouping together the items Upholstered Sofas, Mattresses, and Bedding as representing soft furnishings in the house, contribute the second greatest amount of risk. The main Heat Source for these items is Other Open Flame or Smoking MaterialsItem A Potential Flow Model of a Fire Sprinkler Head(2014) Myers, Taylor Macks; Marshall, Andre W; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Understanding fire sprinkler sprays fills a critical gap in the modeling of fire suppression systems. Previous research has shown that a modeling framework consisting of an instability model coupled with a stochastic transport model can paint most of the sprinkler spray picture, but requires input in the form of the thickness and velocity of unstable fluid sheets. The model outlined forgoes traditional CFD to solve for water jet-deflector interactions, and instead describes the sheet formation as a potential flow boundary value problem, utilizing a free surface formulation and the superposition of the Green's function. The resulting model allows for the determination of the complete flow field over a fire sprinkler head of arbitrary geometry and input conditions. A hypothetical axisymmetric sprinkler is explored to provide insight into the impact of sprinkler head geometry on local fluid as well as complete spray behavior. The resulting flow splits, sheet thicknesses, and sheet velocities are presented for various sprinkler head geometries.Item Transient Fire Load on Aluminum Ferries(2014) Hall, Brian; Gollner, Michael J; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Transient fire load aboard aluminum ferries is studied to determine the contribution of baggage on increasing compartment overhead temperatures. Single-point and average temperature maximums are compared to critical values. A survey of passenger ferry vessels determined the baggage type, carriage rate, and baggage weights to quantify the fire load aboard the vessels. Ferry vessels were examined for potential problem locations. Fire Dynamics Simulator (FDS) by the National institute of Standards and Technology (NIST) was used to model an aluminum ferry compartment. Multiple scenarios are simulated with spread based on a critical heat flux ignition data. The survey determined that the majority of fully loaded aluminum ferries attain higher fuel loads than allowed by Coast Guard requirements. Simulations revealed that the current level of baggage compromises the structural integrity of the aluminum on an average ferry. It is recommended that regulatory changes be made to ensure protection of life and property.Item An Analysis of Thermally Induced Arcing Failure of Electrical Cable(2013) Fisher, Ryan Patrick; Stoliarov, Stanislav I; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Arc failure of Southwire Romex Simpull non-metallic sheathed 14/2 American wire gauge (AWG) with ground cable due to external heat was examined. This type of cable was selected due to its widespread use in residential building wiring. This research is motivated by the fact that currently there are no widely accepted methods or models used to predict electric arc failure in cables exposed to thermal conditions or to determine whether an arc failure event was the cause or result of a fire. A variety of tests were performed at various temperatures to learn more about the arc failure of these cables. The cables were exposed to precise temperatures with a steady heating rate in a convection oven in order to best attempt to eliminate heat transfer through the cable. In order to explore the effect current may have on the time to arc failure of the cable, experiments at different temperatures were performed in both loaded and unloaded scenarios. During many of these tests, voltage and current measurements were collected during an arcing event. As part of the process of exploring the events leading up to arc failure, electrical resistance tests of the cable's insulation components were examined. A model was developed to predict time to arc failure at a variety of temperatures based on thermal degradation of the PVC insulation. The purpose of the developed model is to be able to predict cable failure based on known thermal conditions. The proposed values of the model developed are in examining a prior thermally induced electrical arcing incident or in determining the suitability of a cable in an abnormal thermal environment. The results of this research will be useful in continuing the research and education of the arc failure of electrical cables.Item Prototype Design for Thermoacoustic Flashover Detector(2012) Buda-Ortins, Krystyna Eva; Sunderland, Peter; diMarzo, Marino; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The thermoacoustic flashover detector integrates the phenomenon of thermoacoustics into a fire fighting application. This report presents the prototype design for the thermoacoustic flashover detector to ultimately be implemented in a firefighter's gear. Upon increases in compartment fire heat flux and temperature corresponding to the onset of flashover, the device will produce a loud warning tone to alert the firefighter that flashover is impending. This is critical because post-flashover, the fire transitions to an untenable environment for a firefighter, as well as compromised structural integrity of the building. The current design produces a tone at 115 dB at about 500 Hz upon heating from an external band heater and cooling via an ice/water bath. At 38 mm from the device, this sound level is louder than the 85 dB from fire alarms and distinct from the 3000 Hz tone of smoke detectors. The minimum power input to the device for sound onset is 44 Watts, corresponding to a temperature difference of 150 degrees Celsius at a mean temperature of 225 degrees Celsius across a 2 cm long porous steel wool stack. The temperatures at the hot and cold ends of the stack are 300 and 150 degrees Celsius respectively, which is achieved with a response time of ~100 seconds. The sound is sustained as long as there is a minimum power input of 31 Watts. Although the measurement uncertainties are estimated at 10 degrees Celsius for the temperatures and 5 Watts for the power input, this design provides a foundation for future improvement and quantification of the device. The mechanisms of the thermoacoustics at work and the materials selected for the prototype are presented. Different power level inputs to the device are analyzed and temperatures for operation are determined. Suggestions for future optimization and integration of the device into firefighters' gear are presented.