UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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Now showing 1 - 4 of 4
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    COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF SPATIALLY-RESOLVED SPRAY SCANNING SYSTEM (4S) SPRAY PATTERNS
    (2023) Bors, Jeffrey; Trouve, Arnaud C; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    In computational fluid dynamics (CFD) fire models, sprinkler sprays are represented in complex numerical simulations using Lagrangian particles. These CFD sprays are typically characterized using a combination of experimental data, literature correlations, and estimation. The Spatially-Resolved Spray Scanning System (4S) machine provides high resolution data to characterize sprays for use in CFD analysis, however a quantitative analysis on the effect of this high resolution data with FDS in realistic fire scenarios has not been completed before. 4S spray data is analyzed and compared to a basic spray estimated from literature correlations with and without the presence of fire to analyze trends. In all environments, the basic nozzle overestimated water flux closer to the center of the nozzle and underestimated water flux farther from the center. Differences between the basic and 4S nozzle ranged from 1% to 240% in the enclosure fire scenario. Investigation into the differences showed the polar water distribution to be the most impactful parameter provided by the 4S. Local azimuthal trends were shown to be significant, but non-impactful in the enclosure fire simulation. Global azimuthal trends were apparent but not significant.
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    Assessing the Validity of the Verification Method as a Design Tool
    (2018) Antonsen, Maibritt; Torero, José L; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The Verification Method (VM) as a design tool is becoming more widespread, result-ing in a need for a critique of the concepts behind the method. This project provides the critique by extracting examples from the design processes and solutions of a building being designed using three different approaches: Performance-Based Design, Prescriptive Methods and the VM. The main perceived advantages of the VM is its time efficiency, accessibility and flexibility, while the observed weaknesses include substitution of the designer, the level of under- and over-design and its lack of robustness of the performance criteria and guidance in areas such as fire modeling. It is uncovered how the VM is a design method rather than a tool to demonstrate compliance with the performance require-ments of building codes, which was the original objective of the VM. The Verifica-tion Method must return to its original intentions in order to ensure its validity as a design tool.
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    EFFECTS OF RADIANT HEAT FLUX ON CLEAN AGENT PERFORMANCE FOR CLASS-C STANDARDS
    (2012) Patel, Romil; Milke, James; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This thesis investigates the effects of radiant heat flux on clean agent extinguishing concentrations. This data is sought to support standards that address Class C hazards. Using the REED apparatus, performance of clean agents IG-100, IG-55, IG-541, HFC-125, HFC-227ea and FK-5-1-12 at heat flux levels of 0-40 kW/m2 was examined. It was found that clean agent extinguishing concentrations increased with an added heat flux. An alternate method of testing with the REED apparatus was also examined. Clean agents examined in the test were IG-100, IG-55, IG-541, HFC-125 and HFC-227ea at heat flux levels from 0-5 kW/m2. It was found that clean agent extinguishing concentrations increased by 33 to 45 percent from the original testing method. The new testing method was also found to be more repeatable and less time consuming.
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    Evaluation of the Ability of Fire Dynamic Simulator to Simulate Positive Pressure Ventilation in the Laboratory and Practical Scenarios
    (2005-12-13) Kerber, Steve Ira Newton; Milke, James A; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Positive Pressure Ventilation (PPV) is a tactic that is used on fire grounds across the world everyday, both to improve tenability after the extinguishment of a fire and/or offensively during fire attack to improve firefighting conditions. PPV has proven that it can be a useful tool on the fire ground, but it can also kill or injure fire fighters and civilians if used improperly. Data from three full-scale experiments are compared with simulations completed with the computational fluid dynamic model Fire Dynamic Simulator (FDS). The full-scale experiments characterize a Positive Pressure Ventilation (PPV) fan in an open atmosphere, in a simple room geometry and in a room fire. All experiments qualify and quantify the comparison of the experimental results with the FDS results. A concluding scenario is modeled utilizing the calibration of the full-scale experiments to examine the effects of PPV on a fire in a two-story, colonial style house.