Fire Protection Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/2241
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Item DETECTION OF SIGNATURES FROM INTERNAL CONTAMINANT SOURCES USING INTELLIGENT ALGORITHMS(2023) Anthrathodiyil, Saleel; Milke, James A; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Electrical odors and smoke incidents in aviation have become a pressing concern, with over half of the detector activations resulting in false alarms, leading to uncertainties for flight crews. The escalating costs of diversions and growing awareness of associated health risks underscore the need for more reliable detection and discrimination from false alarms. This study harnesses advanced multi-sensor array technologies, intelligent algorithms, and Metal Oxide Sensors (MOS) sensors equipped with AI capabilities to detect and analyze signatures from candidate internal contaminant sources located in the cockpit. Printed circuit boards from avionics, aviation cables of different insulation, and external contaminant sources were put to failure testing to analyze the early fire signatures. These signatures were subsequently assessed using clustering algorithms and multivariate analysis to pinpoint distinct markers. Comprehensive gas analysis and light obscuration measurements further characterized the environment. Experiments were executed at both the University of Maryland and the Federal Aviation Administration (FAA) tech center, replicating diverse conditions, including an altitude simulation of 8000 ft. The focus was on the capability to distinguish between samples during the smoldering phase, leveraging a multivariate approach and gas analysis. The study also incorporated Aspirating Smoke Detection (ASD) to characterize the responses during large-scale testing. The findings pave the way for identifying and integrating innovative technologies, achieving accurate detection of early-stage signatures from internal contaminants during potential aircraft smoke events.Item COMPARISON OF IGNITION AND COMBUSTION CHARACTERISTICS OF PRESSURE TREATED WOOD AND TREX EXPOSED TO THERMALLY CHARACTERIZED GLOWING FIREBRAND PILES(2023) Lauterbach, Alec; Stoliarov, Stanislov I; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In recent decades, the intensity of wildfires worldwide has escalated, leading to a rise in the destruction of structures and loss of lives within the Wildland-Urban Interface (WUI). Firebrands are small fragments of ignited vegetation or structural material that are carried by the plume of a wildfire, traveling in advance of the main fire front. Firebrand exposure has been recognized as the primary mechanism for the propagation of wildfires as well as a source of ignition of structural elements. However, this complex ignition process of structural elements in the WUI has yet to be fully understood. The ignition and combustion characteristics of a thermoplastic-wood composite (Trex) and Pressure Treated Wood (PTW), two frequently used WUI decking materials, when exposed to glowing firebrand piles were studied using a bench scale wind tunnel. An inert insulation material, ii Kaowool PM, was also used as a deposition substrate to quantify the heat feedback and combustion characteristics of solely the firebrand pile. Firebrand pile densities of 0.16 g cm-2 and 0.06 g cm-2 were deposited on each substrate in rectangular 10 cm x 5 cm orientations and exposed to air flow velocities of 0.9 m s-1, 1.4 m s-1, 2.4 m s-1, and 2.7 m s-1. Infrared camera measurements were used to determine the back surface temperatures of Kaowool PM tests. Using DSLR cameras, surface ignitions of the decking material in front of the firebrand pile (preleading zone ignition events), ignitions on top of the firebrand pile (pile ignition events), and surface ignitions of the decking material behind the firebrand pile (downstream ignition events) were visually quantified via their probability of ignition, time to ignition, and burn duration at each testing condition. A gas analyzer was used to compare combustion characteristics of Trex, PTW, and Kaowool PM tests through heat release rate (HRR) and modified combustion efficiency (MCE). Peak back surface temperatures of the firebrand pile were found to increase with increased air flow up to 2.4 m s-1, and then plateau. The same trend was observed for the ignition probabilities of preleading zone and pile ignition events. The probability of downstream ignition events increased with increasing air flow velocity. Peak HRR increased with increasing air flow velocity. Trex exhibited significantly less smoldering combustion than PTW yet was prone to more intense flaming combustion. When the rectangular 5 cm x 10 cm firebrand pile (10 cm edge facing the airflow), of which the majority of tests were conducted on, was rotated 90 degrees so that the 5 cm edge faced the airflow, the result was a significant decrease in the probability of ignition for both Trex and PTW, along with notable reductions in their HRR and MCE profiles.Item SPHERICAL GAS-FUELED COOL DIFFUSION FLAMES(2022) Kim, Minhyeng; Sunderland, Peter B.; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)An improved understanding of cool diffusion flames could lead to improved engines. These flames are investigated here using a spherical porous burner with gaseous fuels in the microgravity environment of the International Space Station. Normal and inverse flames burning ethane, propane, and n-butane were explored with various fuel and oxygen concentrations, pressures, and flow rates. The diagnostics included an intensified video camera, radiometers, thin-filament pyrometry, and thermocouples. Spherical cool diffusion flames, transitioned from hot flames, burning gases were observed for the first time. However, these cool flames were not readily produced and were only obtained for normal n-butane flames at 2 bar with an ambient oxygen mole fraction of 0.39. The sizes of hot and cool diffusion flames were investigated with the intensified camera images. The hot flames that spawned the cool flames were 2.6 times as large. An analytical model is presented that combines previous models for steady droplet burning and the partial-burning regime for cool diffusion flames. The results identify the importance of burner temperature on the behavior of these cool flames. They also indicate that the observed cool flames reside in rich regions near a mixture fraction of 0.53.Item Effects of Fire Whirl Generator Dimensions on Flame Length and Burning Rate(2020) Dowling, Joseph Lee; Gollner, Michael J; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In-situ burning remains an efficient method of oil spill cleanup, but the implementation of fire whirls over the spilled fuel has the potential increase the speed and efficacy of the process by increasing burning rate and temperature. Logistical requirements would then be placed on the size of the fire whirl generator. A range of wall heights between 0 and55 cm were tested for a fixed-frame fire whirl generator with a liquid fuel source 10.5cm in diameter to analyze the effect on the burning rate and flame length of resulting fire whirls. For very short walls, with heights approximately equal to the fuel pool diameter,an increase of almost double was shown in the mass loss rate. The flame length for the fire whirl increased drastically for wall heights above a critical value of 35 cm, forming stable on-source fire whirls. This indicates that the inflow boundary layer of the fire whirl is a crucial feature causing an increase in the burning rate, while a critical wall height is necessary for aerodynamic effects to form stable on-source fire whirls with extended flame engths.