A polar-drive shock-ignition design for the National Ignition Facilitya)

NASA Astrophysics Data System (ADS)

Anderson, K. S.; Betti, R.; McKenty, P. W.; Collins, T. J. B.; Hohenberger, M.; Theobald, W.; Craxton, R. S.; Delettrez, J. A.; Lafon, M.; Marozas, J. A.; Nora, R.; Skupsky, S.; Shvydky, A.

2013-05-01

Shock ignition [R. Betti et al., Phys. Rev. Lett. 98, 155001 (2007)] is being pursued as a viable option to achieve ignition on the National Ignition Facility (NIF). Shock-ignition target designs use a high-intensity laser spike at the end of a low-adiabat assembly pulse to launch a spherically convergent strong shock to ignite the hot spot of an imploding capsule. A shock-ignition target design for the NIF is presented. One-dimensional simulations indicate an ignition threshold factor of 4.1 with a gain of 58. A polar-drive beam-pointing configuration for shock-ignition experiments on the NIF at 750 kJ is proposed. The capsule design is shown to be robust to the various one- and two-dimensional effects and nonuniformities anticipated on the NIF. The target is predicted to ignite with a gain of 38 when including all anticipated levels of nonuniformity and system uncertainty.

Electrostatic Discharge Initiation Experiments using PVDF Pressure Transducers

DTIC Science & Technology

1991-12-01

ignition sensitivity. The results are discussed within the context of a preliminary model of electrostatic initiation. iii/iv NAVSWC TR 91-666 CONTENTS...Chapter Page 1 INTRODUCTION .......................................... 1-1 TWO PHASE IGNITION MODEL ....................... 1-1 SENSITIZING FACTORS...is necessary to establish effective techniques to reduce the hazards associated with ESD ignition. TWO-PHASE IGNITION MODEL A model has been proposed

Alaska’s changing fire regime - Implications for the vulnerability of its boreal forests

USGS Publications Warehouse

Kasischke, Eric S.; Verbyla, David L.; Rupp, T. Scott; McGuire, A. David; Murphy, Karen A.; Jandt, R.; Barnes, Jennifer L.; Hoy, E.; Duffy, Paul A.; Calef, Monika; Turetsky, Merritt R.

2010-01-01

A synthesis was carried out to examine Alaska’s boreal forest fire regime. During the 2000s, an average of 767 000 ha·year–1 burned, 50% higher than in any previous decade since the 1940s. Over the past 60 years, there was a decrease in the number of lightning-ignited fires, an increase in extreme lightning-ignited fire events, an increase in human-ignited fires, and a decrease in the number of extreme human-ignited fire events. The fraction of area burned from human-ignited fires fell from 26% for the 1950s and 1960s to 5% for the 1990s and 2000s, a result from the change in fire policy that gave the highest suppression priorities to fire events that occurred near human settlements. The amount of area burned during late-season fires increased over the past two decades. Deeper burning of surface organic layers in black spruce (Picea mariana (Mill.) BSP) forests occurred during late-growing-season fires and on more well-drained sites. These trends all point to black spruce forests becoming increasingly vulnerable to the combined changes of key characteristics of Alaska’s fire regime, except on poorly drained sites, which are resistant to deep burning. The implications of these fire regime changes to the vulnerability and resilience of Alaska’s boreal forests and land and fire management are discussed.

Environmental drivers and spatial dependency in wildfire ignition patterns of northwestern Patagonia.

PubMed

Mundo, Ignacio A; Wiegand, Thorsten; Kanagaraj, Rajapandian; Kitzberger, Thomas

2013-07-15

Fire management requires an understanding of the spatial characteristics of fire ignition patterns and how anthropogenic and natural factors influence ignition patterns across space. In this study we take advantage of a recent fire ignition database (855 points) to conduct a comprehensive analysis of the spatial pattern of fire ignitions in the western area of Neuquén province (57,649 km(2)), Argentina, for the 1992-2008 period. The objectives of our study were to better understand the spatial pattern and the environmental drivers of the fire ignitions, with the ultimate aim of supporting fire management. We conducted our analyses on three different levels: statistical "habitat" modelling of fire ignition (natural, anthropogenic, and all causes) based on an information theoretic approach to test several competing hypotheses on environmental drivers (i.e. topographic, climatic, anthropogenic, land cover, and their combinations); spatial point pattern analysis to quantify additional spatial autocorrelation in the ignition patterns; and quantification of potential spatial associations between fires of different causes relative to towns using a novel implementation of the independence null model. Anthropogenic fire ignitions were best predicted by the most complex habitat model including all groups of variables, whereas natural ignitions were best predicted by topographic, climatic and land-cover variables. The spatial pattern of all ignitions showed considerable clustering at intermediate distances (<40 km) not captured by the probability of fire ignitions predicted by the habitat model. There was a strong (linear) and highly significant increase in the density of fire ignitions with decreasing distance to towns (<5 km), but fire ignitions of natural and anthropogenic causes were statistically independent. A two-dimensional habitat model that quantifies differences between ignition probabilities of natural and anthropogenic causes allows fire managers to delineate target areas for consideration of major preventive treatments, strategic placement of fuel treatments, and forecasting of fire ignition. The techniques presented here can be widely applied to situations where a spatial point pattern is jointly influenced by extrinsic environmental factors and intrinsic point interactions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Novel Intrinsic Ignition Method Measuring Local-Global Integration Characterizes Wakefulness and Deep Sleep

PubMed Central

Tagliazucchi, Enzo; Sanjuán, Ana

2017-01-01

Abstract A precise definition of a brain state has proven elusive. Here, we introduce the novel local-global concept of intrinsic ignition characterizing the dynamical complexity of different brain states. Naturally occurring intrinsic ignition events reflect the capability of a given brain area to propagate neuronal activity to other regions, giving rise to different levels of integration. The ignitory capability of brain regions is computed by the elicited level of integration for each intrinsic ignition event in each brain region, averaged over all events. This intrinsic ignition method is shown to clearly distinguish human neuroimaging data of two fundamental brain states (wakefulness and deep sleep). Importantly, whole-brain computational modelling of this data shows that at the optimal working point is found where there is maximal variability of the intrinsic ignition across brain regions. Thus, combining whole brain models with intrinsic ignition can provide novel insights into underlying mechanisms of brain states. PMID:28966977

Novel Intrinsic Ignition Method Measuring Local-Global Integration Characterizes Wakefulness and Deep Sleep.

PubMed

Deco, Gustavo; Tagliazucchi, Enzo; Laufs, Helmut; Sanjuán, Ana; Kringelbach, Morten L

2017-01-01

A precise definition of a brain state has proven elusive. Here, we introduce the novel local-global concept of intrinsic ignition characterizing the dynamical complexity of different brain states. Naturally occurring intrinsic ignition events reflect the capability of a given brain area to propagate neuronal activity to other regions, giving rise to different levels of integration. The ignitory capability of brain regions is computed by the elicited level of integration for each intrinsic ignition event in each brain region, averaged over all events. This intrinsic ignition method is shown to clearly distinguish human neuroimaging data of two fundamental brain states (wakefulness and deep sleep). Importantly, whole-brain computational modelling of this data shows that at the optimal working point is found where there is maximal variability of the intrinsic ignition across brain regions. Thus, combining whole brain models with intrinsic ignition can provide novel insights into underlying mechanisms of brain states.

Spark Ignition of Monodisperse Fuel Sprays. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Danis, Allen M.; Cernansky, Nicholas P.; Namer, Izak

1987-01-01

A study of spark ignition energy requirements was conducted with a monodisperse spray system allowing independent control of droplet size, equivalent ratio, and fuel type. Minimum ignition energies were measured for n-heptane and methanol sprays characterized at the spark gap in terms of droplet diameter, equivalence ratio (number density) and extent of prevaporization. In addition to sprays, minimum ignition energies were measured for completely prevaporized mixtures of the same fuels over a range of equivalence ratios to provide data at the lower limit of droplet size. Results showed that spray ignition was enhanced with decreasing droplet size and increasing equivalence ratio over the ranges of the parameters studied. By comparing spray and prevaporized ignition results, the existence of an optimum droplet size for ignition was indicated for both fuels. Fuel volatility was seen to be a critical factor in spray ignition. The spray ignition results were analyzed using two different empirical ignition models for quiescent mixtures. Both models accurately predicted the experimental ignition energies for the majority of the spray conditions. Spray ignition was observed to be probabilistic in nature, and ignition was quantified in terms of an ignition frequency for a given spark energy. A model was developed to predict ignition frequencies based on the variation in spark energy and equivalence ratio in the spark gap. The resulting ignition frequency simulations were nearly identical to the experimentally observed values.

Human-started wildfires expand the fire niche across the United States.

PubMed

Balch, Jennifer K; Bradley, Bethany A; Abatzoglou, John T; Nagy, R Chelsea; Fusco, Emily J; Mahood, Adam L

2017-03-14

The economic and ecological costs of wildfire in the United States have risen substantially in recent decades. Although climate change has likely enabled a portion of the increase in wildfire activity, the direct role of people in increasing wildfire activity has been largely overlooked. We evaluate over 1.5 million government records of wildfires that had to be extinguished or managed by state or federal agencies from 1992 to 2012, and examined geographic and seasonal extents of human-ignited wildfires relative to lightning-ignited wildfires. Humans have vastly expanded the spatial and seasonal "fire niche" in the coterminous United States, accounting for 84% of all wildfires and 44% of total area burned. During the 21-y time period, the human-caused fire season was three times longer than the lightning-caused fire season and added an average of 40,000 wildfires per year across the United States. Human-started wildfires disproportionally occurred where fuel moisture was higher than lightning-started fires, thereby helping expand the geographic and seasonal niche of wildfire. Human-started wildfires were dominant (>80% of ignitions) in over 5.1 million km 2 , the vast majority of the United States, whereas lightning-started fires were dominant in only 0.7 million km 2 , primarily in sparsely populated areas of the mountainous western United States. Ignitions caused by human activities are a substantial driver of overall fire risk to ecosystems and economies. Actions to raise awareness and increase management in regions prone to human-started wildfires should be a focus of United States policy to reduce fire risk and associated hazards.

Human-started wildfires expand the fire niche across the United States

PubMed Central

Balch, Jennifer K.; Bradley, Bethany A.; Nagy, R. Chelsea; Fusco, Emily J.; Mahood, Adam L.

2017-01-01

The economic and ecological costs of wildfire in the United States have risen substantially in recent decades. Although climate change has likely enabled a portion of the increase in wildfire activity, the direct role of people in increasing wildfire activity has been largely overlooked. We evaluate over 1.5 million government records of wildfires that had to be extinguished or managed by state or federal agencies from 1992 to 2012, and examined geographic and seasonal extents of human-ignited wildfires relative to lightning-ignited wildfires. Humans have vastly expanded the spatial and seasonal “fire niche” in the coterminous United States, accounting for 84% of all wildfires and 44% of total area burned. During the 21-y time period, the human-caused fire season was three times longer than the lightning-caused fire season and added an average of 40,000 wildfires per year across the United States. Human-started wildfires disproportionally occurred where fuel moisture was higher than lightning-started fires, thereby helping expand the geographic and seasonal niche of wildfire. Human-started wildfires were dominant (>80% of ignitions) in over 5.1 million km2, the vast majority of the United States, whereas lightning-started fires were dominant in only 0.7 million km2, primarily in sparsely populated areas of the mountainous western United States. Ignitions caused by human activities are a substantial driver of overall fire risk to ecosystems and economies. Actions to raise awareness and increase management in regions prone to human-started wildfires should be a focus of United States policy to reduce fire risk and associated hazards. PMID:28242690

Some aspects of the CI engine modification aimed at operation on LPG with the application of spark ignition

NASA Astrophysics Data System (ADS)

Kaparuk, J.; Luft, S.; Skrzek, T.; Wojtyniak, M.

2016-09-01

A lot of investigation on modification of the compression ignition engine aimed at operation on LPG with the application of spark ignition has been carried out in the Laboratory of Vehicles and Combustion Engines at Kazimierz Pulaski University of Technology and Humanities in Radom. This paper presents results of investigation on establishment of the proper ignition advance angle in the modified engine. Within the framework of this investigation it was assessed the effect of this regulation on basic engine operating parameters, exhaust emission as well as basic combustion parameters.

Performance metrics for Inertial Confinement Fusion implosions: aspects of the technical framework for measuring progress in the National Ignition Campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spears, B K; Glenzer, S; Edwards, M J

The National Ignition Campaign (NIC) uses non-igniting 'THD' capsules to study and optimize the hydrodynamic assembly of the fuel without burn. These capsules are designed to simultaneously reduce DT neutron yield and to maintain hydrodynamic similarity with the DT ignition capsule. We will discuss nominal THD performance and the associated experimental observables. We will show the results of large ensembles of numerical simulations of THD and DT implosions and their simulated diagnostic outputs. These simulations cover a broad range of both nominal and off nominal implosions. We will focus on the development of an experimental implosion performance metric called themore » experimental ignition threshold factor (ITFX). We will discuss the relationship between ITFX and other integrated performance metrics, including the ignition threshold factor (ITF), the generalized Lawson criterion (GLC), and the hot spot pressure (HSP). We will then consider the experimental results of the recent NIC THD campaign. We will show that we can observe the key quantities for producing a measured ITFX and for inferring the other performance metrics. We will discuss trends in the experimental data, improvement in ITFX, and briefly the upcoming tuning campaign aimed at taking the next steps in performance improvement on the path to ignition on NIF.« less

Performance metrics for inertial confinement fusion implosions: Aspects of the technical framework for measuring progress in the National Ignition Campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spears, Brian K.; Glenzer, S.; Edwards, M. J.

The National Ignition Campaign (NIC) uses non-igniting 'tritium hydrogen deuterium (THD)' capsules to study and optimize the hydrodynamic assembly of the fuel without burn. These capsules are designed to simultaneously reduce DT neutron yield and to maintain hydrodynamic similarity with the DT ignition capsule. We will discuss nominal THD performance and the associated experimental observables. We will show the results of large ensembles of numerical simulations of THD and DT implosions and their simulated diagnostic outputs. These simulations cover a broad range of both nominal and off-nominal implosions. We will focus on the development of an experimental implosion performance metricmore » called the experimental ignition threshold factor (ITFX). We will discuss the relationship between ITFX and other integrated performance metrics, including the ignition threshold factor (ITF), the generalized Lawson criterion (GLC), and the hot spot pressure (HSP). We will then consider the experimental results of the recent NIC THD campaign. We will show that we can observe the key quantities for producing a measured ITFX and for inferring the other performance metrics. We will discuss trends in the experimental data, improvement in ITFX, and briefly the upcoming tuning campaign aimed at taking the next steps in performance improvement on the path to ignition on NIF.« less

[Exposure to electrocution by automotive ignition system in the work environment of car service employees].

PubMed

Fryśkowski, Bernard; Swiatek-Fryśkowska, Dorota

2014-01-01

Automotive ignition system diagnostic procedures involve a specific kind of action due to the presence of high voltage pulses rated of roughly several dozen kilovolts. Therefore, the repairers employed at car service coming into direct contact with electrical equipment of ignition systems are exposed to risk of electric shock. Typically, the electric discharge energy of automotive ignition systems is not high enough to cause fibrillation due to the electric effect on the heart. Nevertheless, there are drivers and car service employees who use electronic cardiac pacemakers susceptible to high voltage pulses. The influence of high-voltage ignition systems on the human body, especially in case of electric injury, has not been comprehensively elucidated. Therefore, relatively few scientific papers address this problem. The aim of this paper is to consider the electrical injury danger from automotive ignition systems, especially in people suffering from cardiac diseases. Some examples of the methods to reduce electric shock probability during diagnostic procedures of spark-ignition combustion engines are presented and discussed.

Tree mortality following a drought-year lightning ignition in the Ouachita Mountains, Arkansas: 2 years postburn

Treesearch

Virginia L. McDaniel; James M. Guldin; Nancy E. Koerth; Jason E. Milks; Rebecca J. Finzer; Ben F. Rowland

2016-01-01

Increasingly, fire managers are using natural ignitions in conjunction with prescribed burns to restore and maintain fire-adapted ecosystems. Increased fuel loading from fire suppression and increasing drought indices associated with climate change, however, may cause natural ignitions to burn with greater intensity and severity. Managers must weigh risk factors versus...

Shock ignition targets: gain and robustness vs ignition threshold factor

NASA Astrophysics Data System (ADS)

Atzeni, Stefano; Antonelli, Luca; Schiavi, Angelo; Picone, Silvia; Volponi, Gian Marco; Marocchino, Alberto

2017-10-01

Shock ignition is a laser direct-drive inertial confinement fusion scheme, in which the stages of compression and hot spot formation are partly separated. The hot spot is created at the end of the implosion by a converging shock driven by a final ``spike'' of the laser pulse. Several shock-ignition target concepts have been proposed and relevant gain curves computed (see, e.g.). Here, we consider both pure-DT targets and more facility-relevant targets with plastic ablator. The investigation is conducted with 1D and 2D hydrodynamic simulations. We determine ignition threshold factors ITF's (and their dependence on laser pulse parameters) by means of 1D simulations. 2D simulations indicate that robustness to long-scale perturbations increases with ITF. Gain curves (gain vs laser energy), for different ITF's, are generated using 1D simulations. Work partially supported by Sapienza Project C26A15YTMA, Sapienza 2016 (n. 257584), Eurofusion Project AWP17-ENR-IFE-CEA-01.

Novel Characterization of Capsule X-Ray Drive at the National Ignition Facility [Using ViewFactor Experiments to Measure Hohlraum X-Radiation Drive from the Capsule Point-of-View in Ignition Experiments on the National Ignition Facility

DOE PAGES

MacLaren, S. A.; Schneider, M. B.; Widmann, K.; ...

2014-03-13

Here, indirect drive experiments at the National Ignition Facility are designed to achieve fusion by imploding a fuel capsule with x rays from a laser-driven hohlraum. Previous experiments have been unable to determine whether a deficit in measured ablator implosion velocity relative to simulations is due to inadequate models of the hohlraum or ablator physics. ViewFactor experiments allow for the first time a direct measure of the x-ray drive from the capsule point of view. The experiments show a 15%–25% deficit relative to simulations and thus explain nearly all of the disagreement with the velocity data. In addition, the datamore » from this open geometry provide much greater constraints on a predictive model of laser-driven hohlraum performance than the nominal ignition target.« less

Factor contribution to fire occurrence, size, and burn probability in a subtropical coniferous forest in East China.

PubMed

Ye, Tao; Wang, Yao; Guo, Zhixing; Li, Yijia

2017-01-01

The contribution of factors including fuel type, fire-weather conditions, topography and human activity to fire regime attributes (e.g. fire occurrence, size distribution and severity) has been intensively discussed. The relative importance of those factors in explaining the burn probability (BP), which is critical in terms of fire risk management, has been insufficiently addressed. Focusing on a subtropical coniferous forest with strong human disturbance in East China, our main objective was to evaluate and compare the relative importance of fuel composition, topography, and human activity for fire occurrence, size and BP. Local BP distribution was derived with stochastic fire simulation approach using detailed historical fire data (1990-2010) and forest-resource survey results, based on which our factor contribution analysis was carried out. Our results indicated that fuel composition had the greatest relative importance in explaining fire occurrence and size, but human activity explained most of the variance in BP. This implies that the influence of human activity is amplified through the process of overlapping repeated ignition and spreading events. This result emphasizes the status of strong human disturbance in local fire processes. It further confirms the need for a holistic perspective on factor contribution to fire likelihood, rather than focusing on individual fire regime attributes, for the purpose of fire risk management.

Fire risk in San Diego County, California: A weighted Bayesian model approach

USGS Publications Warehouse

Kolden, Crystal A.; Weigel, Timothy J.

2007-01-01

Fire risk models are widely utilized to mitigate wildfire hazards, but models are often based on expert opinions of less understood fire-ignition and spread processes. In this study, we used an empirically derived weights-of-evidence model to assess what factors produce fire ignitions east of San Diego, California. We created and validated a dynamic model of fire-ignition risk based on land characteristics and existing fire-ignition history data, and predicted ignition risk for a future urbanization scenario. We then combined our empirical ignition-risk model with a fuzzy fire behavior-risk model developed by wildfire experts to create a hybrid model of overall fire risk. We found that roads influence fire ignitions and that future growth will increase risk in new rural development areas. We conclude that empirically derived risk models and hybrid models offer an alternative method to assess current and future fire risk based on management actions.

Microgravity ignition experiment

NASA Technical Reports Server (NTRS)

Motevalli, Vahid; Elliott, William; Garrant, Keith; Marcotte, Ryan

1992-01-01

The purpose of this project is to develop a flight-ready apparatus of the microgravity ignition experiment for the GASCAN 2 program. The microgravity ignition experiment is designed to study how a microgravity environment affects the time to ignition of a sample of alpha-cellulose paper. A microgravity environment will result in a decrease in the heat transferred from the sample due to a lack of convection currents, which would decrease time to ignition. A lack of convection current would also cause the oxygen supply at the sample not to be renewed, which could delay or even prevent ignition. When this experiment is conducted aboard GASCAN 2, the dominant result of the lack of ignition will be determined. The experiment consists of four canisters containing four thermocouples and a sensor to detect ignition of the paper sample. This year the interior of the canister was redesigned and a mathematical model of the heat transfer around the sample was developed. This heat transfer model predicts an ignition time of approximately 5.5 seconds if the decrease of heat loss from the sample is the dominant factor of the lack of convection currents.

Ignition delay of combustible materials in normoxic equivalent environments

Treesearch

Sara McAllister; Carlos Fernandez-Pello; Gary Ruff; David Urban

2009-01-01

Material flammability is an important factor in determining the pressure and composition (fraction of oxygen and nitrogen) of the atmosphere in the habitable volume of exploration vehicles and habitats. The method chosen in this work to quantify the flammability of a material is by its ease of ignition. The ignition delay time was defined as the time it takes a...

Compression Ignition Engines – Revolutionary Technology That has Civilized Frontiers all Over the Globe from the Industrial Revolution into the Twenty-First Century

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ciatti, Stephen A.

The history, present and future of the compression ignition engine is a fascinating story that spans over 100 years, from the time of Rudolf Diesel to the highly regulated and computerized engines of the 21st Century. The development of these engines provided inexpensive, reliable and high power density machines to allow transportation, construction and farming to be more productive with less human effort than in any previous period of human history. The concept that fuels could be consumed efficiently and effectively with only the ignition of pressurized and heated air was a significant departure from the previous coal-burning architecture ofmore » the 1800s. Today, the compression ignition engine is undergoing yet another revolution. The equipment that provides transport, builds roads and infrastructure, and harvests the food we eat needs to meet more stringent requirements than ever before. How successfully 21st Century engineers are able to make compression ignition engine technology meet these demands will be of major influence in assisting developing nations (with over 50% of the world’s population) achieve the economic and environmental goals they seek.« less

Effects of ignition location models on the burn patterns of simulated wildfires

USGS Publications Warehouse

Bar-Massada, A.; Syphard, A.D.; Hawbaker, T.J.; Stewart, S.I.; Radeloff, V.C.

2011-01-01

Fire simulation studies that use models such as FARSITE often assume that ignition locations are distributed randomly, because spatially explicit information about actual ignition locations are difficult to obtain. However, many studies show that the spatial distribution of ignition locations, whether human-caused or natural, is non-random. Thus, predictions from fire simulations based on random ignitions may be unrealistic. However, the extent to which the assumption of ignition location affects the predictions of fire simulation models has never been systematically explored. Our goal was to assess the difference in fire simulations that are based on random versus non-random ignition location patterns. We conducted four sets of 6000 FARSITE simulations for the Santa Monica Mountains in California to quantify the influence of random and non-random ignition locations and normal and extreme weather conditions on fire size distributions and spatial patterns of burn probability. Under extreme weather conditions, fires were significantly larger for non-random ignitions compared to random ignitions (mean area of 344.5 ha and 230.1 ha, respectively), but burn probability maps were highly correlated (r = 0.83). Under normal weather, random ignitions produced significantly larger fires than non-random ignitions (17.5 ha and 13.3 ha, respectively), and the spatial correlations between burn probability maps were not high (r = 0.54), though the difference in the average burn probability was small. The results of the study suggest that the location of ignitions used in fire simulation models may substantially influence the spatial predictions of fire spread patterns. However, the spatial bias introduced by using a random ignition location model may be minimized if the fire simulations are conducted under extreme weather conditions when fire spread is greatest. ?? 2010 Elsevier Ltd.

Scaling laws for ignition at the National Ignition Facility from first principles.

PubMed

Cheng, Baolian; Kwan, Thomas J T; Wang, Yi-Ming; Batha, Steven H

2013-10-01

We have developed an analytical physics model from fundamental physics principles and used the reduced one-dimensional model to derive a thermonuclear ignition criterion and implosion energy scaling laws applicable to inertial confinement fusion capsules. The scaling laws relate the fuel pressure and the minimum implosion energy required for ignition to the peak implosion velocity and the equation of state of the pusher and the hot fuel. When a specific low-entropy adiabat path is used for the cold fuel, our scaling laws recover the ignition threshold factor dependence on the implosion velocity, but when a high-entropy adiabat path is chosen, the model agrees with recent measurements.

Time to ignition is influenced by both moisture content and soluble carbohydrates in live Douglas fir and Lodgepole pine needles

Treesearch

Matt Jolly; Sara McAllister; Mark Finney; Ann Hadlow

2010-01-01

Living plants are often the primary fuels burning in wildland fire but little is known about the factors that govern their ignition behavior. Moisture content has long been hypothesized to determine the characteristics of fires spreading in live fuels but moisture content alone fails to explain observed differences in the ignition of various species at different times...

Factor contribution to fire occurrence, size, and burn probability in a subtropical coniferous forest in East China

PubMed Central

Guo, Zhixing; Li, Yijia

2017-01-01

The contribution of factors including fuel type, fire-weather conditions, topography and human activity to fire regime attributes (e.g. fire occurrence, size distribution and severity) has been intensively discussed. The relative importance of those factors in explaining the burn probability (BP), which is critical in terms of fire risk management, has been insufficiently addressed. Focusing on a subtropical coniferous forest with strong human disturbance in East China, our main objective was to evaluate and compare the relative importance of fuel composition, topography, and human activity for fire occurrence, size and BP. Local BP distribution was derived with stochastic fire simulation approach using detailed historical fire data (1990–2010) and forest-resource survey results, based on which our factor contribution analysis was carried out. Our results indicated that fuel composition had the greatest relative importance in explaining fire occurrence and size, but human activity explained most of the variance in BP. This implies that the influence of human activity is amplified through the process of overlapping repeated ignition and spreading events. This result emphasizes the status of strong human disturbance in local fire processes. It further confirms the need for a holistic perspective on factor contribution to fire likelihood, rather than focusing on individual fire regime attributes, for the purpose of fire risk management. PMID:28207837

Examining the feasibility of alcohol ignition interlocks for motorcycles : traffic tech.

DOT National Transportation Integrated Search

2017-05-01

Impaired driving is a major factor in vehicle crashes and traffic : fatalities. The use of alcohol ignition interlocks is growing as a : countermeasure to combat the high rate of offender recidivism : for Driving While Intoxicated (DWI); however, whi...

Evaluation of the New Mexico ignition interlock program : traffic tech.

DOT National Transportation Integrated Search

2010-11-01

Impaired driving is a major factor in vehicle crashes and traffic : fatalities. The use of ignition interlocks is growing as a : countermeasure to combat the high rate of offender recidivism : for driving while intoxicated (DWI). New Mexico currently...

Microwave-Assisted Ignition for Improved Internal Combustion Engine Efficiency

NASA Astrophysics Data System (ADS)

DeFilippo, Anthony Cesar

The ever-present need for reducing greenhouse gas emissions associated with transportation motivates this investigation of a novel ignition technology for internal combustion engine applications. Advanced engines can achieve higher efficiencies and reduced emissions by operating in regimes with diluted fuel-air mixtures and higher compression ratios, but the range of stable engine operation is constrained by combustion initiation and flame propagation when dilution levels are high. An advanced ignition technology that reliably extends the operating range of internal combustion engines will aid practical implementation of the next generation of high-efficiency engines. This dissertation contributes to next-generation ignition technology advancement by experimentally analyzing a prototype technology as well as developing a numerical model for the chemical processes governing microwave-assisted ignition. The microwave-assisted spark plug under development by Imagineering, Inc. of Japan has previously been shown to expand the stable operating range of gasoline-fueled engines through plasma-assisted combustion, but the factors limiting its operation were not well characterized. The present experimental study has two main goals. The first goal is to investigate the capability of the microwave-assisted spark plug towards expanding the stable operating range of wet-ethanol-fueled engines. The stability range is investigated by examining the coefficient of variation of indicated mean effective pressure as a metric for instability, and indicated specific ethanol consumption as a metric for efficiency. The second goal is to examine the factors affecting the extent to which microwaves enhance ignition processes. The factors impacting microwave enhancement of ignition processes are individually examined, using flame development behavior as a key metric in determining microwave effectiveness. Further development of practical combustion applications implementing microwave-assisted spark technology will benefit from predictive models which include the plasma processes governing the observed combustion enhancement. This dissertation documents the development of a chemical kinetic mechanism for the plasma-assisted combustion processes relevant to microwave-assisted spark ignition. The mechanism includes an existing mechanism for gas-phase methane oxidation, supplemented with electron impact reactions, cation and anion chemical reactions, and reactions involving vibrationally-excited and electronically-excited species. Calculations using the presently-developed numerical model explain experimentally-observed trends, highlighting the relative importance of pressure, temperature, and mixture composition in determining the effectiveness of microwave-assisted ignition enhancement.

The Evaluation of a Risk Degree for the Process of a Brown Coal Spontaneous Ignition on Dumps with Using of Modern Numeric Methods

NASA Astrophysics Data System (ADS)

Klouda, Petr; Moni, Vlastimil; Řehoř, Michal; Blata, Jan; Helebrant, František

2018-06-01

The article is a summary of information about evaluation of a risk degree for a brown coal spontaneous ignition which is realized on the base of a database analysis of information about the development of stative quantities and desorbated gases in the stored bodies of the brown coal. The data were gained from the long term complex measurements which were realized at chosen companies during the coal mining in the previous parts of the project. In the last part of the project, we examined results of temperature models from thermographs with results of gasses and coal samples from the mines. Then, the influence of atmospheric conditions (insolation, water downfall, changes of barometric pressure etc.), the influence of coal mass degradation, the influence of physical and chemical factors, and the influence of other defective factors on the process of the coal spontaneous ignition. The gasmetry was assess with gas in-situ samples and laboratory gas models of indicative gasses for the spontaneous ignition, which were taken from the method of the thermic oxidation with the aim of the correlation finding for an epicentre of temperature within the spontaneous ignition.

Alaska's Changing Fire Regime - Implications for the Vulnerability of Its Boreal Forests

NASA Technical Reports Server (NTRS)

Kasischke, E. S.; Hoy, E. E.; Verbyla, D. L.; Rupp, T. S.; Duffy, P. A.; McGuire, A. D.; Murphy, K. A.; Jandt, R.; Barnes, J. L.; Calef, M.;

Liquid and gelled sprays for mixing hypergolic propellants using an impinging jet injection system

NASA Astrophysics Data System (ADS)

James, Mark D.

The characteristics of sprays produced by liquid rocket injectors are important in understanding rocket engine ignition and performance. The includes, but is not limited to, drop size distribution, spray density, drop velocity, oscillations in the spray, uniformity of mixing between propellants, and the spatial distribution of drops. Hypergolic ignition and the associated ignition delay times are also important features in rocket engines, providing high reliability and simplicity of the ignition event. The ignition delay time is closely related to the level and speed of mixing between a hypergolic fuel and oxidizer, which makes the injection method and conditions crucial in determining the ignition performance. Although mixing and ignition of liquid hypergolic propellants has been studied for many years, the processes for injection, mixing, and ignition of gelled hypergolic propellants are less understood. Gelled propellants are currently under investigation for use in rocket injectors to combine the advantages of solid and liquid propellants, although not without their own difficulties. A review of hypergolic ignition has been conducted for selected propellants, and methods for achieving ignition have been established. This research is focused on ignition using the liquid drop-on-drop method, as well as the doublet impinging jet injector. The events leading up to ignition, known as pre-ignition stage are discussed. An understanding of desirable ignition and combustion performance requires a study of the effects of injection, temperature, and ambient pressure conditions. A review of unlike-doublet impinging jet injection mixing has also been conducted. This includes mixing factors in reactive and non-reactive sprays. Important mixing factors include jet momentum, jet diameter and length, impingement angle, mass distribution, and injector configuration. An impinging jet injection system is presented using an electro-mechanically driven piston for injecting liquid and gelled hypergolic propellants. A calibration of the system is done with water in preparation for hypergolic injection, and characteristics of individual water and gelled JP-8 jets are studied at velocities in the range of 3 ft/s to 61 ft/s. The piston response is also analyzed to characterize the startup and steady state liquid jet velocities using orifices of 0.02" in diameter. Using this injection system, water and gelled JP-8 sprays are formed and compared across injection velocities of 30 ft/s to 121 ft/s. The comparison includes sheet shape and disintegration, total number of drops, drop size distributions, drop eccentricity, most populated drop bin size, and mean drop sizes. A test matrix for investigating the effects of mixing on ignition of MMH and IRFNA through different injection conditions are presented. First, water and IRFNA are injected to create a spray in the combustion chamber in order to verify effectiveness of test procedures and the test hardware. Next, injection of the hypergolic propellants MMH and IRFNA are done in accordance to the test matrix, although ignition was not observed as expected. These injections are followed by simple drop-on-drop tests to investigate propellant quality and ignition delay. Drop tests are performed with propellants IRFNA/MMH, and again with H2O2/Block 0 as possible propellant replacements for the proposed test plan.

Correlating cookoff violence with pre-ignition damage.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wente, William Baker; Hobbs, Michael L.; Kaneshige, Michael Jiro

Predicting the response of energetic materials during accidents, such as fire, is important for high consequence safety analysis. We hypothesize that responses of ener-getic materials before and after ignition depend on factors that cause thermal and chemi-cal damage. We have previously correlated violence from PETN to the extent of decom-position at ignition, determined as the time when the maximum Damkoehler number ex-ceeds a threshold value. We seek to understand if our method of violence correlation ap-plies universally to other explosive starting with RDX.

Performance of a Laser Ignited Multicylinder Lean Burn Natural Gas Engine

DOE PAGES

Almansour, Bader; Vasu, Subith; Gupta, Sreenath B.; ...

2017-06-06

Market demands for lower fueling costs and higher specific powers in stationary natural gas engines has engine designs trending towards higher in-cylinder pressures and leaner combustion operation. However, Ignition remains as the main limiting factor in achieving further performance improvements in these engines. Addressing this concern, while incorporating various recent advances in optics and laser technologies, laser igniters were designed and developed through numerous iterations. Final designs incorporated water-cooled, passively Q-switched, Nd:YAG micro-lasers that were optimized for stable operation under harsh engine conditions. Subsequently, the micro-lasers were installed in the individual cylinders of a lean-burn, 350 kW, inline 6-cylinder, open-chamber,more » spark ignited engine and tests were conducted. To the best of our knowledge, this is the world’s first demonstration of a laser ignited multi-cylinder natural gas engine. The engine was operated at high-load (298 kW) and rated speed (1800 rpm) conditions. Ignition timing sweeps and excess-air ratio (λ) sweeps were performed while keeping the NOx emissions below the USEPA regulated value (BSNOx < 1.34 g/kW-hr), and while maintaining ignition stability at industry acceptable values (COV_IMEP <5 %). Through such engine tests, the relative merits of (i) standard electrical ignition system, and (ii) laser ignition system were determined. In conclusion, a rigorous combustion data analysis was performed and the main reasons leading to improved performance in the case of laser ignition were identified.« less

Performance of a Laser Ignited Multicylinder Lean Burn Natural Gas Engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Almansour, Bader; Vasu, Subith; Gupta, Sreenath B.

Market demands for lower fueling costs and higher specific powers in stationary natural gas engines has engine designs trending towards higher in-cylinder pressures and leaner combustion operation. However, Ignition remains as the main limiting factor in achieving further performance improvements in these engines. Addressing this concern, while incorporating various recent advances in optics and laser technologies, laser igniters were designed and developed through numerous iterations. Final designs incorporated water-cooled, passively Q-switched, Nd:YAG micro-lasers that were optimized for stable operation under harsh engine conditions. Subsequently, the micro-lasers were installed in the individual cylinders of a lean-burn, 350 kW, inline 6-cylinder, open-chamber,more » spark ignited engine and tests were conducted. To the best of our knowledge, this is the world’s first demonstration of a laser ignited multi-cylinder natural gas engine. The engine was operated at high-load (298 kW) and rated speed (1800 rpm) conditions. Ignition timing sweeps and excess-air ratio (λ) sweeps were performed while keeping the NOx emissions below the USEPA regulated value (BSNOx < 1.34 g/kW-hr), and while maintaining ignition stability at industry acceptable values (COV_IMEP <5 %). Through such engine tests, the relative merits of (i) standard electrical ignition system, and (ii) laser ignition system were determined. In conclusion, a rigorous combustion data analysis was performed and the main reasons leading to improved performance in the case of laser ignition were identified.« less

Importance of the gas phase role to the prediction of energetic material behavior: An experimental study

NASA Astrophysics Data System (ADS)

Ali, A. N.; Son, S. F.; Asay, B. W.; Sander, R. K.

2005-03-01

Various thermal (radiative, conductive, and convective) initiation experiments are performed to demonstrate the importance of the gas phase role in combustion modeling of energetic materials (EM). A previously published condensed phase model that includes a predicted critical irradiance above which ignition is not possible is compared to experimental laser ignition results for octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and 2,4,6-trinitrotoluene (TNT). Experimental results conflict with the predicted critical irradiance concept. The failure of the model is believed to result from a misconception about the role of the gas phase in the ignition process of energetic materials. The model assumes that ignition occurs at the surface and that evolution of gases inhibits ignition. High speed video of laser ignition, oven cook-off and hot wire ignition experiments captures the ignition of HMX and TNT in the gas phase. A laser ignition gap test is performed to further evaluate the effect of gas phase laser absorption and gas phase disruption on the ignition process. Results indicate that gas phase absorption of the laser energy is probably not the primary factor governing the gas phase ignition observations. It is discovered that a critical gap between an HMX pellet and a salt window of 6mm±0.4mm exists below which ignition by CO2 laser is not possible at the tested irradiances of 29W /cm2 and 38W/cm2 for HMX ignition. These observations demonstrate that a significant disruption of the gas phase, in certain scenarios, will inhibit ignition, independent of any condensed phase processes. These results underscore the importance of gas phase processes and illustrate that conditions can exist where simple condensed phase models are inadequate to accurately predict the behavior of energetic materials.

Prospects of lean ignition with the quarter wave coaxial cavity igniter

NASA Astrophysics Data System (ADS)

Pertl, Franz Andreas Johannes

New ignition sources are needed to operate the next generation of lean high efficiency internal combustion engines. A significant environmental and economic benefit could be obtained from these lean engines. Toward this goal, the quarter wave coaxial cavity resonator, QWCCR, igniter was examined. A detailed theoretical analysis of the resonator was performed relating geometric and material parameters to performance characteristics, such as resonator quality factor and developed tip electric field. The analysis provided for the construction and evaluation of a resonator for ignition testing. The evaluation consisted of ignition tests with liquefied-petroleum-gas (LPG) air mixtures of varying composition. The combustion of these mixtures was contained in a closed steel vessel with a precombustion pressure near one atmosphere. The resonator igniter was fired in this vessel with a nominal 150 W microwave pulse of varying duration, to determine ignition energy limits for various mixtures. The mixture compositions were determined by partial pressure measurement and the ideal gas law. Successful ignition was determined through observation of the combustion through a view port. The pulse and reflected microwave power were captured in real time with a high-speed digital storage oscilloscope. Ignition energies and power levels were calculated from these measurements. As a comparison, these ignition experiments were also carried out with a standard non-resistive spark plug, where gap voltage and current were captured for energy calculations. The results show that easily ignitable mixtures around stoichiometric and slightly rich compositions are ignitable with the QWCCR using the similar kinds of energies as the conventional spark plug in the low milli-Joule range. Energies for very lean mixtures could not be determined reliably for the QWCCR for this prototype test, but could be lower than that for a conventional spark. Given the capability of high power, high energy delivery, and opportunity for optimization, the QWCCR has the potential to deliver more energy per unit time than a conventional spark plug and thus should be considered be as a lean ignition source.

Relative effects of climatic and local factors on fire occurrence in boreal forest landscapes of northeastern China.

PubMed

Wu, Zhiwei; He, Hong S; Yang, Jian; Liu, Zhihua; Liang, Yu

2014-09-15

Fire significantly affects species composition, structure, and ecosystem processes in boreal forests. Our study objective was to identify the relative effects of climate, vegetation, topography, and human activity on fire occurrence in Chinese boreal forest landscapes. We used historical fire ignition for 1966-2005 and the statistical method of Kernel Density Estimation to derive fire-occurrence density (number of fires/km(2)). The Random Forest models were used to quantify the relative effects of climate, vegetation, topography, and human activity on fire-occurrence density. Our results showed that fire-occurrence density tended to be spatially clustered. Human-caused fire occurrence was highly clustered at the southern part of the region, where human population density is high (comprising about 75% of the area's population). In the north-central areas where elevations are the highest in the region and less densely populated, lightning-caused fires were clustered. Climate factors (e.g., fine fuel and duff moisture content) were important at both regional and landscape scales. Human activity factors (e.g., distance to nearest settlement and road) were secondary to climate as the primary fire occurrence factors. Predictions of fire regimes often assume a strong linkage between climate and fire but usually with less emphasis placed on the effects of local factors such as human activity. We therefore suggest that accurate forecasting of fire regime should include human influences such as those measured by forest proximity to roads and human settlements. Copyright © 2014 Elsevier B.V. All rights reserved.

Output testing of small-arms primers

NASA Technical Reports Server (NTRS)

Bement, Laurence J.; Doris, Thomas A.; Schimmel, Morry L.

1991-01-01

The performance of two standard primers for initiating small-caliber ammunition are compared to that of a primer for initiating aircraft escape-system components. Three testing methods are employed including: (1) firing the primer to measure total energy delivered; (2) monitoring output in terms of gaseous product-mass flow rate and pressure as a function of time; and (3) firing the primer onto ignition material to study gas pressure produced during ignition and burning as a function of time. The results of the test demonstrate differences in the ignitability factors of the standard primers and time peak pressures of less than 100 microseconds. One unexpected result is that two percussion primers (the FA-41 and the M42C1) developed for different applications have the same ignitability. The ignitability test method is shown to yield the most useful data and can be used to specify percussion primers and optimize their performance.

A novel three-axis cylindrical hohlraum designed for inertial confinement fusion ignition

NASA Astrophysics Data System (ADS)

Kuang, Longyu; Li, Hang; Jing, Longfei; Lin, Zhiwei; Zhang, Lu; Li, Liling; Ding, Yongkun; Jiang, Shaoen; Liu, Jie; Zheng, Jian

2016-10-01

A novel ignition hohlraum for indirect-drive inertial confinement fusion is proposed, which is named three-axis cylindrical hohlraum (TACH). TACH is a kind of 6 laser entrance holes (LEHs) hohlraum, which is orthogonally jointed of three cylindrical hohlraums. Laser beams are injected through every entrance hole with the same incident angle of 55°. A view-factor simulation result shows that the time-varying drive asymmetry of TACH is less than 1.0% in the whole drive pulse period without any supplementary technology. Coupling efficiency of TACH is close to that of 6 LEHs spherical hohlraum with corresponding size. Its plasma-filling time is close to that of typical cylindrical ignition hohlraum. Its laser plasma interaction has as low backscattering as the outer cone of the cylindrical ignition hohlraum. Therefore, TACH combines most advantages of various hohlraums and has little predictable risk, providing an important competitive candidate for ignition hohlraum.

A novel three-axis cylindrical hohlraum designed for inertial confinement fusion ignition

PubMed Central

Kuang, Longyu; Li, Hang; Jing, Longfei; Lin, Zhiwei; Zhang, Lu; Li, Liling; Ding, Yongkun; Jiang, Shaoen; Liu, Jie; Zheng, Jian

2016-01-01

A novel ignition hohlraum for indirect-drive inertial confinement fusion is proposed, which is named three-axis cylindrical hohlraum (TACH). TACH is a kind of 6 laser entrance holes (LEHs) hohlraum, which is orthogonally jointed of three cylindrical hohlraums. Laser beams are injected through every entrance hole with the same incident angle of 55°. A view-factor simulation result shows that the time-varying drive asymmetry of TACH is less than 1.0% in the whole drive pulse period without any supplementary technology. Coupling efficiency of TACH is close to that of 6 LEHs spherical hohlraum with corresponding size. Its plasma-filling time is close to that of typical cylindrical ignition hohlraum. Its laser plasma interaction has as low backscattering as the outer cone of the cylindrical ignition hohlraum. Therefore, TACH combines most advantages of various hohlraums and has little predictable risk, providing an important competitive candidate for ignition hohlraum. PMID:27703250

A novel three-axis cylindrical hohlraum designed for inertial confinement fusion ignition.

PubMed

Kuang, Longyu; Li, Hang; Jing, Longfei; Lin, Zhiwei; Zhang, Lu; Li, Liling; Ding, Yongkun; Jiang, Shaoen; Liu, Jie; Zheng, Jian

2016-10-05

A novel ignition hohlraum for indirect-drive inertial confinement fusion is proposed, which is named three-axis cylindrical hohlraum (TACH). TACH is a kind of 6 laser entrance holes (LEHs) hohlraum, which is orthogonally jointed of three cylindrical hohlraums. Laser beams are injected through every entrance hole with the same incident angle of 55°. A view-factor simulation result shows that the time-varying drive asymmetry of TACH is less than 1.0% in the whole drive pulse period without any supplementary technology. Coupling efficiency of TACH is close to that of 6 LEHs spherical hohlraum with corresponding size. Its plasma-filling time is close to that of typical cylindrical ignition hohlraum. Its laser plasma interaction has as low backscattering as the outer cone of the cylindrical ignition hohlraum. Therefore, TACH combines most advantages of various hohlraums and has little predictable risk, providing an important competitive candidate for ignition hohlraum.

Ignition Delay of Combustible Materials in Normoxic Equivalent Environments

NASA Technical Reports Server (NTRS)

McAllister, Sara; Fernandez-Pello, Carlos; Ruff, Gary; Urban, David

2009-01-01

Material flammability is an important factor in determining the pressure and composition (fraction of oxygen and nitrogen) of the atmosphere in the habitable volume of exploration vehicles and habitats. The method chosen in this work to quantify the flammability of a material is by its ease of ignition. The ignition delay time was defined as the time it takes a combustible material to ignite after it has been exposed to an external heat flux. Previous work in the Forced Ignition and Spread Test (FIST) apparatus has shown that the ignition delay in the currently proposed space exploration atmosphere (approximately 58.6 kPa and32% oxygen concentration) is reduced by 27% compared to the standard atmosphere used in the Space Shuttle and Space Station. In order to determine whether there is a safer environment in terms of material flammability, a series of piloted ignition delay tests using polymethylmethacrylate (PMMA) was conducted in the FIST apparatus to extend the work over a range of possible exploration atmospheres. The exploration atmospheres considered were the normoxic equivalents, i.e. reduced pressure conditions with a constant partial pressure of oxygen. The ignition delay time was seen to decrease as the pressure was reduced along the normoxic curve. The minimum ignition delay observed in the normoxic equivalent environments was nearly 30% lower than in standard atmospheric conditions. The ignition delay in the proposed exploration atmosphere is only slightly larger than this minimum. Interms of material flammability, normoxic environments with a higher pressure relative to the proposed pressure would be desired.

Feasibility study of liquid pool burning in reduced gravity

NASA Technical Reports Server (NTRS)

Kanury, A. M.

1979-01-01

The feasibility of conducting experiments in the Spacelab on ignition and flame spread with liquid fuel pools which are initially at a temperature lower than the fuel's flash point temperature was studied. Theories were developed for the ignition and flame spread processes, and experiments were conducted to understand the factors influencing the ignition process and the spread rate. The results were employed to devise a conceptual Spacelab experiment which is expected to be feasible for a safe conduct and to be suitable for obtaining crucial data on the concerned processes.

Indirect drive ignition at the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meezan, N. B.; Edwards, M. J.; Hurricane, O. A.

This article reviews scientific results from the pursuit of indirect drive ignition on the National Ignition Facility (NIF) and describes the program's forward looking research directions. In indirect drive on the NIF, laser beams heat an x-ray enclosure called a hohlraum that surrounds a spherical pellet. X-ray radiation ablates the surface of the pellet, imploding a thin shell of deuterium/tritium (DT) that must accelerate to high velocity (v > 350 km s -1) and compress by a factor of several thousand. Since 2009, substantial progress has been made in understanding the major challenges to ignition: Rayleigh Taylor (RT) instability seededmore » by target imperfections; and low-mode asymmetries in the hohlraum x-ray drive, exacerbated by laser-plasma instabilities (LPI). Requirements on velocity, symmetry, and compression have been demonstrated separately on the NIF but have not been achieved simultaneously. We now know that the RT instability, seeded mainly by the capsule support tent, severely degraded DT implosions from 2009–2012. Experiments using a 'high-foot' drive with demonstrated lower RT growth improved the thermonuclear yield by a factor of 10, resulting in yield amplification due to alpha particle heating by more than a factor of 2. However, large time dependent drive asymmetry in the LPI-dominated hohlraums remains unchanged, preventing further improvements. High fidelity 3D hydrodynamic calculations explain these results. In conclusion, future research efforts focus on improved capsule mounting techniques and on hohlraums with little LPI and controllable symmetry. In parallel, we are pursuing improvements to the basic physics models used in the design codes through focused physics experiments.« less

Indirect drive ignition at the National Ignition Facility

DOE PAGES

Meezan, N. B.; Edwards, M. J.; Hurricane, O. A.; ...

2016-10-27

This article reviews scientific results from the pursuit of indirect drive ignition on the National Ignition Facility (NIF) and describes the program's forward looking research directions. In indirect drive on the NIF, laser beams heat an x-ray enclosure called a hohlraum that surrounds a spherical pellet. X-ray radiation ablates the surface of the pellet, imploding a thin shell of deuterium/tritium (DT) that must accelerate to high velocity (v > 350 km s -1) and compress by a factor of several thousand. Since 2009, substantial progress has been made in understanding the major challenges to ignition: Rayleigh Taylor (RT) instability seededmore » by target imperfections; and low-mode asymmetries in the hohlraum x-ray drive, exacerbated by laser-plasma instabilities (LPI). Requirements on velocity, symmetry, and compression have been demonstrated separately on the NIF but have not been achieved simultaneously. We now know that the RT instability, seeded mainly by the capsule support tent, severely degraded DT implosions from 2009–2012. Experiments using a 'high-foot' drive with demonstrated lower RT growth improved the thermonuclear yield by a factor of 10, resulting in yield amplification due to alpha particle heating by more than a factor of 2. However, large time dependent drive asymmetry in the LPI-dominated hohlraums remains unchanged, preventing further improvements. High fidelity 3D hydrodynamic calculations explain these results. In conclusion, future research efforts focus on improved capsule mounting techniques and on hohlraums with little LPI and controllable symmetry. In parallel, we are pursuing improvements to the basic physics models used in the design codes through focused physics experiments.« less

76 FR 63659 - Notice Pursuant to the National Cooperative Research and Production Act of 1993; Cooperative...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-13

... Production Act of 1993; Cooperative Research Group on Pre-Ignition Prevention Program Notice is hereby given... Research Group on Pre-Ignition Prevention Programs (``P3'') has filed written notifications simultaneously... planned activity is to develop a fundamental understanding of the factors that lead to low speed pre...

Fundamental Studies of Ignition Process in Large Natural Gas Engines Using Laser Spark Ignition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azer Yalin; Bryan Willson

Past research has shown that laser ignition provides a potential means to reduce emissions and improve engine efficiency of gas-fired engines to meet longer-term DOE ARES (Advanced Reciprocating Engine Systems) targets. Despite the potential advantages of laser ignition, the technology is not seeing practical or commercial use. A major impediment in this regard has been the 'open-path' beam delivery used in much of the past research. This mode of delivery is not considered industrially practical owing to safety factors, as well as susceptibility to vibrations, thermal effects etc. The overall goal of our project has been to develop technologies andmore » approaches for practical laser ignition systems. To this end, we are pursuing fiber optically coupled laser ignition system and multiplexing methods for multiple cylinder engine operation. This report summarizes our progress in this regard. A partial summary of our progress includes: development of a figure of merit to guide fiber selection, identification of hollow-core fibers as a potential means of fiber delivery, demonstration of bench-top sparking through hollow-core fibers, single-cylinder engine operation with fiber delivered laser ignition, demonstration of bench-top multiplexing, dual-cylinder engine operation via multiplexed fiber delivered laser ignition, and sparking with fiber lasers. To the best of our knowledge, each of these accomplishments was a first.« less

Effect of cavity configuration on kerosene spark ignition in a scramjet combustor at Ma 4.5 flight condition

NASA Astrophysics Data System (ADS)

Bao, Heng; Zhou, Jin; Pan, Yu

2015-12-01

Spark ignition experiments of liquid kerosene are conducted in a scramjet model equipped with dual-cavities at Ma 4.5 flight condition with a stagnation temperature of 1032 K. The ignition ability of two cavities with different length is compared and analyzed based on the wall pressure distribution along the combustor and the thrust evolution. The experimental results indicate that the longer cavity (L/D=7) is more suitable than the smaller cavity (L/D=5) in spark ignition. When employing the smaller cavity, three steady combustion states are observed after spark ignition. The concept of 'local flame' is adopted to explain the expanding problem of weak combustion. The local equivalence ratio in the shear layer is the dominated factor in determining the developing process of local flame. The final steady combustion mode of the combustor is dependent on the flame developing process. When employing the longer cavity, the establishment of intense combustion state can be much easier.

Differences in human versus lightning fires between urban and rural areas of the boreal forest in interior Alaska

USGS Publications Warehouse

Calef, Monika; Varvak, Anna; McGuire, A. David

2017-01-01

In western North America, the carbon-rich boreal forest is experiencing warmer temperatures, drier conditions and larger and more frequent wildfires. However, the fire regime is also affected by direct human activities through suppression, ignition, and land use changes. Models are important predictive tools for understanding future conditions but they are based on regional generalizations of wildfire behavior and weather that do not adequately account for the complexity of human–fire interactions. To achieve a better understanding of the intensity of human influence on fires in this sparsely populated area and to quantify differences between human and lightning fires, we analyzed fires by both ignition types in regard to human proximity in urban (the Fairbanks subregion) and rural areas of interior Alaska using spatial (Geographic Information Systems) and quantitative analysis methods. We found substantial differences in drivers of wildfire: while increases in fire ignitions and area burned were caused by lightning in rural interior Alaska, in the Fairbanks subregion these increases were due to human fires, especially in the wildland urban interface. Lightning fires are starting earlier and fires are burning longer, which is much more pronounced in the Fairbanks subregion than in rural areas. Human fires differed from lightning fires in several ways: they started closer to settlements and highways, burned for a shorter duration, were concentrated in the Fairbanks subregion, and often occurred outside the brief seasonal window for lightning fires. This study provides important insights that improve our understanding of the direct human influence on recently observed changes in wildfire regime with implications for both fire modeling and fire management.

Application of wildfire simulation methods to assess wildfire exposure in a Mediterranean fire-prone area (Sardinia, Italy)

NASA Astrophysics Data System (ADS)

Salis, M.; Ager, A.; Arca, B.; Finney, M.; Bacciu, V. M.; Spano, D.; Duce, P.

2012-12-01

Spatial and temporal patterns of fire spread and behavior are dependent on interactions among climate, topography, vegetation and fire suppression efforts (Pyne et al. 1996; Viegas 2006; Falk et al. 2007). Humans also play a key role in determining frequency and spatial distribution of ignitions (Bar Massada et al, 2011), and thus influence fire regimes as well. The growing incidence of catastrophic wildfires has led to substantial losses for important ecological and human values within many areas of the Mediterranean basin (Moreno et al. 1998; Mouillot et al. 2005; Viegas et al. 2006a; Riaño et al. 2007). The growing fire risk issue has led to many new programs and policies of fuel management and risk mitigation by environmental and fire agencies. However, risk-based methodologies to help identify areas characterized by high potential losses and prioritize fuel management have been lacking for the region. Formal risk assessment requires the joint consideration of likelihood, intensity, and susceptibility, the product of which estimates the chance of a specific loss (Brillinger 2003; Society of Risk Analysis, 2006). Quantifying fire risk therefore requires estimates of a) the probability of a specific location burning at a specific intensity and location, and b) the resulting change in financial or ecological value (Finney 2005; Scott 2006). When large fires are the primary cause of damage, the application of this risk formulation requires modeling fire spread to capture landscape properties that affect burn probability. Recently, the incorporation of large fire spread into risk assessment systems has become feasible with the development of high performance fire simulation systems (Finney et al. 2011) that permit the simulation of hundreds of thousands of fires to generate fine scale maps of burn probability, flame length, and fire size, while considering the combined effects of weather, fuels, and topography (Finney 2002; Andrews et al. 2007; Ager and Finney 2009; Finney et al. 2009; Salis et al. 2012 accepted). In this work, we employed wildfire simulation methods to quantify wildfire exposure to human and ecological values for the island of Sardinia, Italy. The work was focused on the risk and exposure posed by large fires (e.g. 100 - 10,000 ha), and considers historical weather, ignition patterns and fuels. We simulated 100,000 fires using burn periods that replicated the historical size distribution on the Island, and an ignition probability grid derived from historic ignition data. We then examine spatial variation in three exposure components (burn probability, flame length, fire size) among important human and ecological values. The results allowed us to contract exposure among and within the various features examined, and highlighted the importance of human factors in shaping wildfire exposure in Sardinia. The work represents the first application of burn probability modeling in the Mediterranean region, and sets the stage for expanded work in the region to quantify risk from large fires

Laser ignition - Spark plug development and application in reciprocating engines

NASA Astrophysics Data System (ADS)

Pavel, Nicolaie; Bärwinkel, Mark; Heinz, Peter; Brüggemann, Dieter; Dearden, Geoff; Croitoru, Gabriela; Grigore, Oana Valeria

2018-03-01

Combustion is one of the most dominant energy conversion processes used in all areas of human life, but global concerns over exhaust gas pollution and greenhouse gas emission have stimulated further development of the process. Lean combustion and exhaust gas recirculation are approaches to improve the efficiency and to reduce pollutant emissions; however, such measures impede reliable ignition when applied to conventional ignition systems. Therefore, alternative ignition systems are a focus of scientific research. Amongst others, laser induced ignition seems an attractive method to improve the combustion process. In comparison with conventional ignition by electric spark plugs, laser ignition offers a number of potential benefits. Those most often discussed are: no quenching of the combustion flame kernel; the ability to deliver (laser) energy to any location of interest in the combustion chamber; the possibility of delivering the beam simultaneously to different positions, and the temporal control of ignition. If these advantages can be exploited in practice, the engine efficiency may be improved and reliable operation at lean air-fuel mixtures can be achieved, making feasible savings in fuel consumption and reduction in emission of exhaust gasses. Therefore, laser ignition can enable important new approaches to address global concerns about the environmental impact of continued use of reciprocating engines in vehicles and power plants, with the aim of diminishing pollutant levels in the atmosphere. The technology can also support increased use of electrification in powered transport, through its application to ignition of hybrid (electric-gas) engines, and the efficient combustion of advanced fuels. In this work, we review the progress made over the last years in laser ignition research, in particular that aimed towards realizing laser sources (or laser spark plugs) with dimensions and properties suitable for operating directly on an engine. The main envisaged solutions for positioning of the laser spark plug, i.e. placing it apart from or directly on the engine, are introduced. The path taken from the first solution proposed, to build a compact laser suitable for ignition, to the practical realization of a laser spark plug is described. Results obtained by ignition of automobile test engines, with laser devices that resemble classical spark plugs, are specifically discussed. It is emphasized that technological advances have brought this method of laser ignition close to the application and installation in automobiles powered by gasoline engines. Achievements made in the laser ignition of natural gas engines are outlined, as well as the utilization of laser ignition in other applications. Scientific and technical advances have allowed realization of laser devices with multiple (up to four) beam outputs, but many other important aspects (such as integration, thermal endurance or vibration strength) are still to be solved. Recent results of multi-beam ignition of a single-cylinder engine in a test bench set-up are encouraging and have led to increased research interest in this direction. A fundamental understanding of the processes involved in laser ignition is crucial in order to exploit the technology's full potential. Therefore, several measurement techniques, primarily optical types, used to characterize the laser ignition process are reviewed in this work.

76 FR 59922 - Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-28

... the document is a factor of 8,887 grams of CO 2 per gallon of gasoline for conversion of gasoline fuel...-ignition vehicles and alternative fuel spark- ignition vehicles. CO 2 emissions test group result (grams per mile)/8,887 grams per gallon of gasoline fuel) x (10\\2\\) = Fuel consumption test group result...

Turbojet-engine Starting and Acceleration

NASA Technical Reports Server (NTRS)

Mc Cafferty, R. J.; Straight, D. M.

1956-01-01

From considerations of safety and reliability in performance of gas-turbine aircraft, it is clear that engine starting and acceleration are of utmost importance. For this reason extensive efforts have been devoted to the investigation of the factors involved in the starting and acceleration of engines. In chapter III it is shown that certain basic combustion requirements must be met before ignition can occur; consequently, the design and operation of an engine must be tailored to provide these basic requirements in the combustion zone of the engine, particularly in the vicinity of the ignition source. It is pointed out in chapter III that ignition by electrical discharges is aided by high pressure, high temperature, low gas velocity and turbulence, gaseous fuel-air mixture, proper mixture strength, and-an optimum spark. duration. The simultaneous achievement of all these requirements in an actual turbojet-engine combustor is obviously impossible, yet any attempt to satisfy as many requirements as possible will result in lower ignition energies, lower-weight ignition systems, and greater reliability. These factors together with size and cost considerations determine the acceptability of the final ignition system. It is further shown in chapter III that the problem of wall quenching affects engine starting. For example, the dimensions of the volume to be burned must be larger than the quenching distance at the lowest pressure and the most adverse fuel-air ratio encountered. This fact affects the design of cross-fire tubes between adjacent combustion chambers in a tubular-combustor turbojet engine. Only two chambers in these engines contain spark plugs; therefore, the flame must propagate through small connecting tubes between the chambers. The quenching studies indicate that if the cross-fire tubes are too narrow the flame will not propagate from one chamber to another. In order to better understand the role of the basic factors in actual engine operation, many investigations have been conducted in single combustors from gas-turbine engines and in full-scale engines in altitude tanks and in flight. The purpose of the present chapter is to discuss the results of such studies and, where possible, to interpret these results qualitatively in terms of the basic requirements reported in chapter III. The discussion parallels the three phases of turbojet engine starting: (1) Ignition of the fuel-air mixture (2) Propagation of flame throughout the combustion zone (3) Acceleration of the engine to operating speed.

Human-ignited wildfire patterns and responses to policy shifts

Treesearch

M. L. Chas-Amil; J. P. Prestemon; C. J. McClean; J. Touza

2015-01-01

Development of efficient forest wildfire policies requires an understanding of the underlying reasons behind forest fire occurrences. Globally, there is a close relationship between forest wildfires and human activities; most wildfires are human events due to negligence (e.g., agricultural burning escapes) and deliberate actions (e.g., vandalism, pyromania, revenge,...

Ignition of global wildfires at the Cretaceous/Tertiary boundary

NASA Technical Reports Server (NTRS)

Melosh, H. J.; Schneider, N. M.; Zahnle, K. J.; Latham, D.

1990-01-01

The recent discovery of an apparently global soot layer at the Cretaceous/Tertiary boundary indicates that global wildfires were somehow ignited by the impact of a comet or asteroid. It is shown here that the thermal radiation produced by the ballistic reentry of ejecta condensed from the vapor plume of the impact could have increased the global radiation flux by factors of 50 to 150 times the solar input for periods ranging from one to several hours. This great increase in thermal radiation may have been responsible for the ignition of global wildfires, as well as having deleterious effects on unprotected animal life.

Some Wildfire Ignition Causes Pose More Risk of Destroying Houses than Others

PubMed Central

Penman, Trent D.; Price, Owen F.

2016-01-01

Many houses are at risk of being destroyed by wildfires. While previous studies have improved our understanding of how, when and why houses are destroyed by wildfires, little attention has been given to how these fires started. We compiled a dataset of wildfires that destroyed houses in New South Wales and Victoria and, by comparing against wildfires where no houses were destroyed, investigated the relationship between the distribution of ignition causes for wildfires that did and did not destroy houses. Powerlines, lightning and deliberate ignitions are the main causes of wildfires that destroyed houses. Powerlines were 6 times more common in the wildfires that destroyed houses data than in the wildfires where no houses were destroyed data and lightning was 2 times more common. For deliberate- and powerline-caused wildfires, temperature, wind speed, and forest fire danger index were all significantly higher and relative humidity significantly lower (P < 0.05) on the day of ignition for wildfires that destroyed houses compared with wildfires where no houses were destroyed. For all powerline-caused wildfires the first house destroyed always occurred on the day of ignition. In contrast, the first house destroyed was after the day of ignition for 78% of lightning-caused wildfires. Lightning-caused wildfires that destroyed houses were significantly larger (P < 0.001) in area than human-caused wildfires that destroyed houses. Our results suggest that targeting fire prevention strategies around ignition causes, such as improving powerline safety and targeted arson reduction programmes, and reducing fire spread may decrease the number of wildfires that destroy houses. PMID:27598325

Some Wildfire Ignition Causes Pose More Risk of Destroying Houses than Others.

PubMed

Collins, Kathryn M; Penman, Trent D; Price, Owen F

2016-01-01

Many houses are at risk of being destroyed by wildfires. While previous studies have improved our understanding of how, when and why houses are destroyed by wildfires, little attention has been given to how these fires started. We compiled a dataset of wildfires that destroyed houses in New South Wales and Victoria and, by comparing against wildfires where no houses were destroyed, investigated the relationship between the distribution of ignition causes for wildfires that did and did not destroy houses. Powerlines, lightning and deliberate ignitions are the main causes of wildfires that destroyed houses. Powerlines were 6 times more common in the wildfires that destroyed houses data than in the wildfires where no houses were destroyed data and lightning was 2 times more common. For deliberate- and powerline-caused wildfires, temperature, wind speed, and forest fire danger index were all significantly higher and relative humidity significantly lower (P < 0.05) on the day of ignition for wildfires that destroyed houses compared with wildfires where no houses were destroyed. For all powerline-caused wildfires the first house destroyed always occurred on the day of ignition. In contrast, the first house destroyed was after the day of ignition for 78% of lightning-caused wildfires. Lightning-caused wildfires that destroyed houses were significantly larger (P < 0.001) in area than human-caused wildfires that destroyed houses. Our results suggest that targeting fire prevention strategies around ignition causes, such as improving powerline safety and targeted arson reduction programmes, and reducing fire spread may decrease the number of wildfires that destroy houses.

Asynchronous Timing of Lightning Strikes and Santa Ana Winds in Southern California

NASA Astrophysics Data System (ADS)

Bendix, J.; Hartnett, J. J.

2016-12-01

In Southern California, "Santa Ana" foehn winds are thought to be responsible for the most extreme fire weather conditions, and have contributed to many of the largest wildfires on record. In recent decades, the majority of wildfires in the region, whether during Santa Ana wind (SAW) conditions or not, have been caused by humans. But absent human influence, the only likely natural ignition source is lightning. Downslope foehn winds seem unlikely to coincide with the convection that favors lightning, raising the question of how frequently natural ignition would be available when Santa Ana winds are blowing. We address this question by examining the extent to which lightning actually occurs during SAW conditions. We use daily lightning counts downloaded from the NOAA Severe Weather Data Inventory (in turn derived from the Vaisala National Lightning Detection Network) and the compilation of SAW days published by Abatzoglou et al. in 2013 to determine how frequently lightning struck on SAW days. We counted all strikes recorded in Los Angeles, San Bernardino, Riverside, Orange and San Diego counties during the period 1986-2010. Our results indicate that lightning rarely coincides with Santa Ana conditions. In our 25-year study period, there were 694 SAW days. Only 22 of those (3.2%) experienced any lightning at all. This contrasts with non-SAW days, 20% of which experienced at least some lightning within the five county region. The lightning that did occur was sparse: an average of 10.6 strikes per day on those SAW days that did experience it, compared with an average of 398.8 strikes/day on the non-SAW days that experienced lightning. These results suggest that the fire regime prior to EuroAmerican settlement may have been significantly different from that which has prevailed for the past century or more. Some fires may have occurred under Santa Ana conditions - whether started by Native Americans, or by lighting that struck earlier, and smoldered until SAW conditions arose. But it does seem clear that ignition was limited during Santa Ana conditions. Debates over the impact of EuroAmericans on southern California fire regimes have focused on the role of fire suppression; a more important factor may have been provision of abundant ignitions under extreme fire weather conditions from which they would otherwise have been absent.

Combustion characteristics of fine- and micro-pulverized coal in the mixture of O{sub 2}/CO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiangyong Huang; Xiumin Jiang; Xiangxin Han

The effects of oxygen concentration, particle size, and heating rate on the coal combustion characteristics under an O{sub 2}/CO{sub 2} atmosphere were investigated. The results indicated that the oxygen concentration played the most important role. As the oxygen concentration increases, the ignition and burnout temperatures decrease and the comprehensive combustion property index S increases. Moreover, the improvement of the oxygen concentration intensified the effects of the other factors. The ignition mechanism changes from hetero-homogeneous type to homogeneous type as the oxygen concentration increases. The ignition and burnout temperatures decrease slightly as the mean particle size decreases, and the index Smore » increases measurably as the mean particle size decreases. The heating rate has different effects on the ignition temperature, burnout temperature, and index S at different oxygen concentrations. 19 refs., 9 figs., 2 tabs.« less

Stabilization of high-compression, indirect-drive inertial confinement fusion implosions using a 4-shock adiabat-shaped drive

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacPhee, A. G.; Peterson, J. L.; Casey, D. T.

Hydrodynamic instabilities and poor fuel compression are major factors for capsule performance degradation in ignition experiments on the National Ignition Facility. Using a recently developed laser drive profile with a decaying first shock to tune the ablative Richtmyer-Meshkov (ARM) instability and subsequent in-flight Rayleigh-Taylor growth, we have demonstrated reduced growth compared to the standard ignition pulse whilst maintaining conditions for a low fuel adiabat needed for increased compression. Using in-flight x-ray radiography of pre-machined modulations, the first growth measurements using this new ARM-tuned drive have demonstrated instability growth reduction of ∼4× compared to the original design at a convergence ratiomore » of ∼2. Corresponding simulations give a fuel adiabat of ∼1.6, similar to the original goal and consistent with ignition requirements.« less

Stabilization of high-compression, indirect-drive inertial confinement fusion implosions using a 4-shock adiabat-shaped drive

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacPhee, A. G.; Peterson, J. L.; Casey, D. T.

Hydrodynamic instabilities and poor fuel compression are major factors for capsule performance degradation in ignition experiments on the National Ignition Facility. Using a recently developed laser drive profile with a decaying first shock to tune the ablative Richtmyer-Meshkov (ARM) instability and subsequent in-flight Rayleigh-Taylor growth, we have demonstrated reduced growth compared to the standard ignition pulse whilst maintaining conditions for a low fuel adiabat needed for increased compression. Here, using in-flight x-ray radiography of pre-machined modulations, the first growth measurements using this new ARM-tuned drive have demonstrated instability growth reduction of ~4× compared to the original design at a convergencemore » ratio of ~2. Corresponding simulations give a fuel adiabat of ~1.6, similar to the original goal and consistent with ignition requirements.« less

Stabilization of high-compression, indirect-drive inertial confinement fusion implosions using a 4-shock adiabat-shaped drive

DOE PAGES

MacPhee, A. G.; Peterson, J. L.; Casey, D. T.; ...

2015-08-01

Hydrodynamic instabilities and poor fuel compression are major factors for capsule performance degradation in ignition experiments on the National Ignition Facility. Using a recently developed laser drive profile with a decaying first shock to tune the ablative Richtmyer-Meshkov (ARM) instability and subsequent in-flight Rayleigh-Taylor growth, we have demonstrated reduced growth compared to the standard ignition pulse whilst maintaining conditions for a low fuel adiabat needed for increased compression. Here, using in-flight x-ray radiography of pre-machined modulations, the first growth measurements using this new ARM-tuned drive have demonstrated instability growth reduction of ~4× compared to the original design at a convergencemore » ratio of ~2. Corresponding simulations give a fuel adiabat of ~1.6, similar to the original goal and consistent with ignition requirements.« less

Human impacts on 20th century fire dynamics and implications for global carbon and water trajectories

NASA Astrophysics Data System (ADS)

Li, F.; Lawrence, D. M.; Bond-Lamberty, B. P.

2017-12-01

Fire is a fundamental Earth system process and the primary ecosystem disturbance on the global scale. It affects carbon and water cycles through its impact on terrestrial ecosystems, and at the same time, is regulated by weather and climate, vegetation characteristics, and, importantly, human ignition and efforts to suppress fires (i.e., the direct human effect on fire). Here, we utilize the Community Land Model version 4.5 (CLM4.5) to generate a quantitative understanding of the impacts on fire dynamics and associated carbon and water cycling that can be attributed to changes in human ignition and suppression over the 20th century. We find that the net impact of increases in human ignition and suppression significantly reduce the 20th century averaged global burned area by 38 Mha/yr. The reduction increases since 1920, rising to 103 Mha/yr less burned area at the end of the century. Land carbon gain is weakened by 17% over the 20th century, mainly due to increased human deforestation fires and associated escape fires (i.e., degradation fires) in the tropical humid forests, even though the decrease in burned area in many other regions due to human fire suppression acts to increase land carbon gain. The direct human effect on fire also weakens the 20th century upward trend of global runoff by 6%, and enhances the upward trend in global evaportranspiration since 1945 by 7%. In addition, the above impacts in densely populated, highly developed (if population density > 0.1 person/km2), or moderately populated and developed regions are of opposite sign to those in other regions. Our study suggests that particular attention should be paid to human deforestation and degradation fires in the tropical humid forests when reconstructing and projecting fire carbon emissions and net atmosphere-land carbon exchange and estimating resultant impacts of direct human effect on fire.

VASCULAR RESPONSE TO TRAFFIC-DERIVED INHALATION IN HUMANS

EPA Science Inventory

By coordinating closely with Center Projects 1-3, we will determine whether specific aspects of traffic-derived exposure (primary vs. secondary organics, particulate vs. gases, spark-ignition vs. diesel engine vs. a mixture) enhance the human vascular response to pollutants. W...

Mechanism of Start and Development of Aircraft Crash Fires

NASA Technical Reports Server (NTRS)

Pinkel, I. Irving; Preston, G. Merritt; Pesman, Gerard J.

1952-01-01

Full-scale aircraft crashes were made to investigate the mechanism of the start and development of aircraft crash fires. The results are discussed herein. This investigation revealed the characteristics of the ignition sources, the manner in which the combustibles spread, the mechanism of the union of the combustibles and ignition sources, and the pertinent factors governing the development of a crash fire as observed in this program.

Major wildfires at the Cretaceous-Tertiary boundary

NASA Technical Reports Server (NTRS)

Anders, Edward; Wolbach, Wendy S.; Gilmour, Iain

1991-01-01

The current status of the reconstruction of major biomass fire events at the Cretaceous-Tertiary boundary is discussed. Attention is given to the sources of charcoal and soot, the identification of biomass and fossil carbon, and such ignition-related problems as delated fires, high atmospheric O2 content, ignition mechanisms, and the greenhouse-effect consequences of fire on the scale envisioned. Consequences of these factors for species extinction patterns are noted.

Igniter adapter-to-igniter chamber deflection test

NASA Technical Reports Server (NTRS)

Cook, M.

1990-01-01

Testing was performed to determine the maximum RSRM igniter adapter-to-igniter chamber joint deflection at the crown of the inner joint primary seal. The deflection data was gathered to support igniter inner joint gasket resiliency predictions which led to launch commit criteria temperature determinations. The proximity (deflection) gage holes for the first test (Test No. 1) were incorrectly located; therefore, the test was declared a non-test. Prior to Test No. 2, test article configuration was modified with the correct proximity gage locations. Deflection data were successfully acquired during Test No. 2. However, the proximity gage deflection measurements were adversely affected by temperature increases. Deflections measured after the temperature rise at the proximity gages were considered unreliable. An analysis was performed to predict the maximum deflections based on the reliable data measured before the detectable temperature rise. Deflections to the primary seal crown location were adjusted to correspond to the time of maximum expected operating pressure (2,159 psi) to account for proximity gage bias, and to account for maximum attach and special bolt relaxation. The maximum joint deflection for the igniter inner joint at the crown of the primary seal, accounting for all significant correction factors, was 0.0031 in. (3.1 mil). Since the predicted (0.003 in.) and tested maximum deflection values were sufficiently close, the launch commit criteria was not changed as a result of this test. Data from this test should be used to determine if the igniter inner joint gasket seals are capable of maintaining sealing capability at a joint displacement of (1.4) x (0.0031 in.) = 0.00434 inches. Additional testing should be performed to increase the database on igniter deflections and address launch commit criteria temperatures.

Numerical investigation of spontaneous flame propagation under RCCI conditions

DOE PAGES

Bhagatwala, Ankit V; Sankaran, Ramanan; Kokjohn, Sage; ...

2015-06-30

This paper presents results from one and two-dimensional direct numerical simulations under Reactivity Controlled Compression Ignition (RCCI) conditions of a primary reference fuel (PRF) mixture consisting of n-heptane and iso-octane. RCCI uses in-cylinder blending of two fuels with different autoignition characteristics to control combustion phasing and the rate of heat release. These simulations employ an improved model of compression heating through mass source/sink terms developed in a previous work by Bhagatwala et al. (2014), which incorporates feedback from the flow to follow a predetermined experimental pressure trace. Two-dimensional simulations explored parametric variations with respect to temperature stratification, pressure profiles andmore » n-heptane concentration. Furthermore, statistics derived from analysis of diffusion/reaction balances locally normal to the flame surface were used to elucidate combustion characteristics for the different cases. Both deflagration and spontaneous ignition fronts were observed to co-exist, however it was found that higher n-heptane concentration provided a greater degree of flame propagation, whereas lower n-heptane concentration (higher fraction of iso-octane) resulted in more spontaneous ignition fronts. A significant finding was that simulations initialized with a uniform initial temperature and a stratified n-heptane concentration field, resulted in a large fraction of combustion occurring through flame propagation. The proportion of spontaneous ignition fronts increased at higher pressures due to shorter ignition delay when other factors were held constant. For the same pressure and fuel concentration, the contribution of flame propagation to the overall combustion was found to depend on the level of thermal stratification, with higher initial temperature gradients resulting in more deflagration and lower gradients generating more ignition fronts. Statistics of ignition delay are computed to assess the Zel’dovich (1980) theory for the mode of combustion propagation based on ignition delay gradients.« less

Modeling anthropogenic and natural fire ignitions in an inner-alpine valley

NASA Astrophysics Data System (ADS)

Vacchiano, Giorgio; Foderi, Cristiano; Berretti, Roberta; Marchi, Enrico; Motta, Renzo

2018-03-01

Modeling and assessing the factors that drive forest fire ignitions is critical for fire prevention and sustainable ecosystem management. In southern Europe, the anthropogenic component of wildland fire ignitions is especially relevant. In the Alps, however, the role of fire as a component of disturbance regimes in forest and grassland ecosystems is poorly known. The aim of this work is to model the probability of fire ignition for an Alpine region in Italy using a regional wildfire archive (1995-2009) and MaxEnt modeling. We analyzed separately (i) winter forest fires, (ii) winter fires on grasslands and fallow land, and (iii) summer fires. Predictors were related to morphology, climate, and land use; distance from infrastructures, number of farms, and number of grazing animals were used as proxies for the anthropogenic component. Collinearity among predictors was reduced by a principal component analysis. Regarding ignitions, 30 % occurred in agricultural areas and 24 % in forests. Ignitions peaked in the late winter-early spring. Negligence from agrosilvicultural activities was the main cause of ignition (64 %); lightning accounted for 9 % of causes across the study time frame, but increased from 6 to 10 % between the first and second period of analysis. Models for all groups of fire had a high goodness of fit (AUC 0.90-0.95). Temperature was proportional to the probability of ignition, and precipitation was inversely proportional. Proximity from infrastructures had an effect only on winter fires, while the density of grazing animals had a remarkably different effect on summer (positive correlation) and winter (negative) fires. Implications are discussed regarding climate change, fire regime changes, and silvicultural prevention. Such a spatially explicit approach allows us to carry out spatially targeted fire management strategies and may assist in developing better fire management plans.

Human influence on the abundance and connectivity of high-risk fuels in mixed forests of northern Wisconsin, USA

Treesearch

Brian R. Sturtevant; Patrick A. Zoller; Eric J. Gustafson; David T. Cleland

2004-01-01

Though fire is considered a "natural" disturbance, humans heavily influence modern wildfire regimes. Humans influence fires both directly, by igniting and suppressing fires, and indirectly, by either altering vegetation, climate, or both. We used the LANDIS disturbance and succession model to compare the relative importance of a direct human influence (...

Human influence on the abundance and connectivity of high-risk fuels in mixed forests of northern Wisconsin, USA

Treesearch

Brian R. Sturtevant; Patrick A. Zollner; Eric J. Gustafson; David T. Cleland

2004-01-01

Though fire is considered a "natural" disturbance, humans heavily influence modern wildfire regimes. Humans influence fires both directly, by igniting and suppressing fires, and indirectly, by either altering vegetation, climate, or both. We used the LANDIS disturbance and succession model to compare the relative importance of a direct human influence...

Definition of Time Induction of Self-Ignition of the Substance on the Prognostic Extrapolation Depending on the Basis of Indicators Fire and Explosion Hazard

NASA Astrophysics Data System (ADS)

Sechin, A.; Kyrmakova, O.; Osipenko, S.

2016-01-01

In this article the research directed on development of a technique of definition of time of induction of the self-ignition of substances and materials which is an indicator of the beginning of development of an emergency is conducted. The experiment consisting in supervision over process of self-ignition of coal and oil deposits was the basis for research. On the basis of experimental data the curve expressing analytic - expected dependence of size of temperature of ignition on induction time was constructed. Proceeding from graphical representation of process, functional dependence of time of induction on a temperature indicator was received: y = 16920 • x0 537. By means of known indicators of such substances as bitumen oil oxidized (the combustible solid substance received by oxidation of residual product of oil refining) and tar oil (the combustible solid substance which is residual product of oil refining) and the received algorithm, verification of reliability of the received dependence and a technique of definition of time of induction of spontaneous ignition of deposits of oil in general was carried out. The practical importance of the conducted research is that having data on time of induction of process of self-ignition, by means of preventive measures becomes possible to avoid and prevent accidents in oil and oil processing branches, at the same time loss of property and loss of human life.

Hair ignition by dye laser for port-wine stain: risk factors evaluated.

PubMed

Molin, L; Hallgren, S

1999-04-01

Flashlamp-pumped pulsed dye laser is the preferred treatment for port-wine stain. Vascular hemoglobin and epidermal melanin are competing sites for dye laser absorption and damage. The case presented illustrates the potential hazard of ignition induced by dye laser treatment on the face of a patient receiving inhalation anesthesia. A 6-year-old girl with almost black hair was treated for a port-wine stain covering most of the right half of her face. She was treated with dye laser under general anesthesia administered by mask. A laser pulse close to the upper part of the eyebrow induced a blaze and the eyebrow was instantly destroyed by the fire. Regrowth of the eyebrow was complete after a few months. Hair specimens of various colors were exposed experimentally to dye laser irradiation in room and oxygen-saturated atmospheres. Risk factors of ignition are high laser dosage, a high oxygen level, repeated pulses and dark colored hair.

Point design targets, specifications, and requirements for the 2010 NIF ignition campaign

NASA Astrophysics Data System (ADS)

Haan, Steven

2010-11-01

A set of point design targets has been specified for the initial ignition campaign on the National Ignition Facility [G. Miller, E. Moses, and C. Wuest, Opt. Eng. 443, 2841 (2004)]. The targets use an ablator of either Be(Cu) or CH(Ge). They are imploded in a U or Au hohlraum at peak radiation temperature 270 to 300eV. Considerations determining the point design include laser-plasma interactions, hydro stability, laser operations, and target fabrication. Simulations were used to evaluate choices, to define requirements, and to estimate sensitivity to uncertainties. Designs were updated to account for 2009 experimental results. We describe a formalism to evaluate the margin for ignition, in a parameter the Ignition Threshold Factor (ITF). Uncertainty and shot-to-shot variability can be evaluated, as well as sensitivity to systematic uncertainties. The formalism is used to estimate the probability of ignition for each target. In collaboration with J Lindl, D Callahan, D Clark, J Salmonson, B Hammel, L Atherton, R Cook, J Edwards, S Glenzer, A Hamza, S Hatchett, D Hinkel, D Ho, O Jones, O Landen, B MacGowan, M Marinak, E Moses, D Munro, S Pollaine, B Spears, P Springer, L Suter, C Thomas, R Town, S Weber, D Wilson, G Kyrala, M Herrmann, R Olson, R Vesey, A Nikroo, H Huang, and K Moreno.

Influence of several factors on ignition lag in a compression-ignition engine

NASA Technical Reports Server (NTRS)

Gerrish, Harold C; Voss, Fred

1932-01-01

This investigation was made to determine the influence of fuel quality, injection advance angle, injection valve-opening pressure, inlet-air pressure, compression ratio, and engine speed on the time lag of auto-ignition of a Diesel fuel oil in a single-cylinder compression-ignition engine as obtained from an analysis of indicator diagrams. Three cam-operated fuel-injection pumps, two pumps cams, and an automatic injection valve with two different nozzles were used. Ignition lag was considered to be the interval between the start of injection of the fuel as determined with a Stroborama and the start of effective combustion as determined from the indicator diagram, the latter being the point where 4.0 x 10(exp-6) pound of fuel had been effectively burned. For this particular engine and fuel it was found that: (1) for a constant start and the same rate of fuel injection up the point of cut-off, a variation in fuel quantity from 1.2 x 10(exp-4) to 4.1 x 10(exp-4) pound per cycle has no appreciable effect on the ignition lag; (2) injection advance angle increases or decreases the lag according to whether density, temperature, or turbulence has the controlling influence; (3) increase in valve-opening pressure slightly increases the lag; and (4) increase of inlet-air pressure, compression ratio, and engine speed reduces the lag.

21 CFR 172.859 - Sucrose fatty acid esters.

Code of Federal Regulations, 2013 CFR

2013-04-01

... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN... value is not more than 6. (4) The residue on ignition (sulfated ash) is not more than 2 percent. (5) The... fresh apples, avocados, bananas, banana plantains, limes, melons (honeydew and cantaloupe), papaya...

21 CFR 172.859 - Sucrose fatty acid esters.

Code of Federal Regulations, 2012 CFR

2012-04-01

... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN... value is not more than 6. (4) The residue on ignition (sulfated ash) is not more than 2 percent. (5) The... fresh apples, avocados, bananas, banana plantains, limes, melons (honeydew and cantaloupe), papaya...

21 CFR 172.859 - Sucrose fatty acid esters.

Code of Federal Regulations, 2010 CFR

2010-04-01

... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN... value is not more than 6. (4) The residue on ignition (sulfated ash) is not more than 2 percent. (5) The... fresh apples, avocados, bananas, banana plantains, limes, melons (honeydew and cantaloupe), papaya...

21 CFR 172.859 - Sucrose fatty acid esters.

Code of Federal Regulations, 2011 CFR

2011-04-01

... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN... value is not more than 6. (4) The residue on ignition (sulfated ash) is not more than 2 percent. (5) The... fresh apples, avocados, bananas, banana plantains, limes, melons (honeydew and cantaloupe), papaya...

Spreaders, igniters, and burning shrubs: plant flammability explains novel fire dynamics in grass-invaded deserts.

PubMed

Fuentes-Ramirez, Andres; Veldman, Joseph W; Holzapfel, Claus; Moloney, Kirk A

2016-10-01

Novel fire regimes are an important cause and consequence of global environmental change that involve interactions among biotic, climatic, and human components of ecosystems. Plant flammability is key to these interactions, yet few studies directly measure flammability or consider how multiple species with different flammabilities interact to produce novel fire regimes. Deserts of the southwestern United States are an ideal system for exploring how novel fire regimes can emerge when fire-promoting species invade ecosystems comprised of species that did not evolve with fire. In these deserts, exotic annual grasses provide fuel continuity across landscapes that did not historically burn. These fires often ignite a keystone desert shrub, the fire-intolerant creosote bush, Larrea tridentata (DC.) Coville. Ignition of Larrea is likely catalyzed by fuels produced by native plants that grow beneath the shrubs. We hypothesize that invasive and native species exhibit distinct flammability characteristics that in combination determine spatial patterns of fire spread and intensity. We measured flammability metrics of Larrea, two invasive grasses, Schismus arabicus and Bromus madritensis, and two native plants, the sub-shrub Ambrosia dumosa and the annual herb Amsinckia menziesii. Results of laboratory experiments show that the grasses carry fire quickly (1.32 cm/s), but burn for short duration (0.5 min) at low temperatures. In contrast, native plants spread fire slowly (0.12 cm/s), but burn up to eight times longer (4 min) and produced hotter fires. Additional experiments on the ignition requirements of Larrea suggest that native plants burn with sufficient temperature and duration to ignite dead Larrea branches (time to ignition, 2 min; temperature at ignition 692°C). Once burning, these dead branches ignite living branches in the upper portions of the shrub. Our study provides support for a conceptual model in which exotic grasses are "spreaders" of fire and native plants growing beneath shrubs are "igniters" of dead Larrea branches. Once burning, flames produced by dead branches engulf the entire shrub, resulting in locally intense fires without historical precedent in this system. We suggest that fire models and conservation-focused management could be improved by incorporating the distinct flammability characteristics and spatial distributions of spreaders, igniters, and keystone shrubs. © 2016 by the Ecological Society of America.

Combustion in a High-Speed Compression-Ignition Engine

NASA Technical Reports Server (NTRS)

Rothrock, A M

1933-01-01

An investigation conducted to determine the factors which control the combustion in a high-speed compression-ignition engine is presented. Indicator cards were taken with the Farnboro indicator and analyzed according to the tangent method devised by Schweitzer. The analysis show that in a quiescent combustion chamber increasing the time lag of auto-ignition increases the maximum rate of combustion. Increasing the maximum rate of combustion increases the tendency for detonation to occur. The results show that by increasing the air temperature during injection the start of combustion can be forced to take place during injection and so prevent detonation from occurring. It is shown that the rate of fuel injection does not in itself control the rate of combustion.

Progress Toward Ignition on the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kauffman, R L

2011-10-17

The principal approach to ignition on the National Ignition Facility (NIF) is indirect drive. A schematic of an ignition target is shown in Figure 1. The laser beams are focused through laser entrance holes at each end of a high-Z cylindrical case, or hohlraum. The lasers irradiate the hohlraum walls producing x-rays that ablate and compress the fuel capsule in the center of the hohlraum. The hohlraum is made of Au, U, or other high-Z material. For ignition targets, the hohlraum is {approx}0.5 cm diameter by {approx}1 cm in length. The hohlraum absorbs the incident laser energy producing x-rays formore » symmetrically imploding the capsule. The fuel capsule is a {approx}2-mm-diameter spherical shell of CH, Be, or C filled with DT fuel. The DT fuel is in the form of a cryogenic layer on the inside of the capsule. X-rays ablate the outside of the capsule, producing a spherical implosion. The imploding shell stagnates in the center, igniting the DT fuel. NIC has overseen installation of all of the hardware for performing ignition experiments, including commissioning of approximately 50 diagnostic systems in NIF. The diagnostics measure scattered optical light, x-rays from the hohlraum over the energy range from 100 eV to 500 keV, and x-rays, neutrons, and charged particles from the implosion. An example of a diagnostic is the Magnetic Recoil Spectrometer (MRS) built by a collaboration of scientists from MIT, UR-LLE, and LLNL shown in Figure 2. MRS measures the neutron spectrum from the implosion, providing information on the neutron yield and areal density that are metrics of the quality of the implosion. Experiments on NIF extend ICF research to unexplored regimes in target physics. NIF can produce more than 50 times the laser energy and more than 20 times the power of any previous ICF facility. Ignition scale hohlraum targets are three to four times larger than targets used at smaller facilities, and the ignition drive pulses are two to five times longer. The larger targets and longer pulse lengths produce unique plasma conditions for laser-plasma instabilities that could reduce hohlraum coupling efficiency. Initial experiments have demonstrated efficient coupling of laser energy to x-rays. X-ray drive greater than 300 eV has been measured in gas-filled ignition hohlraum and shows the expected scaling with laser energy and hohlraum scale size. Experiments are now optimizing capsule implosions for ignition. Ignition conditions require assembling the fuel with sufficient density and temperature for thermonuclear burn. X-rays ablate the outside of the capsule, accelerating and spherically compressing the capsule for assembling the fuel. The implosion stagnates, heating the central core and producing a hot spot that ignites and burns the surrounding fuel. The four main characteristics of the implosion are shell velocity, central hot spot shape, fuel adiabat, and mix. Experiments studying these four characteristics of implosions are used to optimize the implosion. Integrated experiments using cryogenic fuel layer experiments demonstrate the quality of the implosion as the optimization experiments progress. The final compressed fuel conditions are diagnosed by measuring the x-ray emission from the hot core and the neutrons and charged particles produced in the fusion reactions. Metrics of the quality of the implosion are the neutron yield and the shell areal density, as well as the size and shape of the core. The yield depends on the amount of fuel in the hot core and its temperature and is a gauge of the energy coupling to the fuel. The areal density, the density of the fuel times its thickness, diagnoses the fuel assembly, which is measured using the fraction of neutrons that are down scattered passing through the dense shell. The yield and fraction of down scattered neutrons, or shell rho-r, from the cryogenic layered implosions are shown in Figure 3. The different sets of data represent results after a series of implosion optimization experiments. Both yield and areal density show significant increases as a result of the optimization. The experimental Ignition Threshold Factor (ITFX) is a measure of the progress toward ignition. ITFX is analogous to the Lawson Criterion in Magnetic Fusion. Implosions have improved by over a factor of 50 since the first cryogenic layered experiments were done in September 2010. This increase is a measure of the progress made toward the ignition goal in the past year. Optimization experiments are planned in the coming year for continued improvement in implosion performance to achieve the ignition goal. In summary, NIF has made significant progress toward ignition in the 30 months since project completion. Diagnostics and all of the supporting equipment are in place for ignition experiments. The Ignition Campaign is under way as a national collaborative effort of all the National Nuclear Security Administration (NNSA) science laboratories as well as international partners.« less

Digital forestry in the wildland urban interface

Treesearch

Michael C. Wimberly; Yangjian Zhang; John A. Stanturf

2006-01-01

Growing human populations have led to the expansion of the Wildland-Urban interface (WUI) across the southeastern United States. The juxtaposition of buildings, infrastructure, and forests in the WUI creates challenges for natural resource managers. The presence of flammable vegetation, high rates of human-caused ignitions and high building densities combine to...

Digital forestry in the wildland-urban interface

Treesearch

Michael C. Wimberly; Yangjian Zhang; John A. Stanturf

2006-01-01

Growing human populations have led to the expansion of the Wildland-Urban Interface (WUI) across the southeastern United States. The juxtaposition of buildings, infrastructure. and forests in the WUI creates challenges for natural resource managers. The presence of flammable vegetation. high rates of human-caused ignitions and high building densities combine to...

What does it take to start an oropharyngeal fire? Oxygen requirements to start fires in the operating room.

PubMed

Roy, Soham; Smith, Lee P

2011-02-01

Airway fires are a well-described and potentially devastating complication of oropharyngeal surgery. However, the actual factors required to ignite the fire have never been well-delineated in the medical literature. In this study, we used a mechanical model to assess the oxygen parameters necessary to cause an oropharyngeal fire. An electrosurgical unit (Bovie) was grounded to a whole raw chicken and a 6.0 endotracheal tube (ETT) was inserted into the cranial end of the degutted central cavity. Oxygen (O(2)) was then titrated through the ETT tube at varying concentrations, with flow rates varying from 10 to 15L/min. Electrocautery (at a setting of 15W) was performed on tissue in the central cavity of the chicken near the ETT. All trials were repeated twice to ensure accuracy. Positive test results were quantified by the time required to obtain ignition of any part of the mechanical setup and time required to produce a sustained flame. A test was considered negative if no ignition could be obtained after four minutes of direct electrocautery. At an O(2) concentration of 100% and a flow rate of 15L/min, ignition with a sustained flame was obtained between 15 and 30s after initiation of electrocautery. At 100% O(2) at 10L/min, ignition was obtained at 70s with immediate sustained flame. At an O(2) concentration of 60%, ignition occurred at 25s and sustained fire after 60s. At an O(2) concentration of 50% ignition with a sustained flame occurred between 128 and 184s. At an O(2) concentration of 45%, neither ignition nor sustained flames could be obtained in any trial. Operating room fires remain a genuine danger when performing oropharyngeal surgery where electrocautery is performed in an oxygen-enriched environment. In our study, higher O(2) flow rates with higher FiO(2) correlated with quicker ignition in the chicken cavity. A fire was easily obtained when using 100% O(2); as the O(2) concentration decreases, longer exposure to electrocautery is required for ignition. Below 50% O(2) we were unable to obtain ignition. Our study is the first to examine the relative risk of ignition and sustained fire in a mechanical model of oropharyngeal surgery. Decreasing the fraction of inspired O(2) (FiO(2)) to less than 50% may substantially decrease the risk of airway fire during oropharyngeal surgery. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Vegetation Fires in the Coupled Human-Earth System Under Future Environmental and Policy Perspectives

NASA Astrophysics Data System (ADS)

le page, Y.; Morton, D. C.; Hurtt, G. C.

2013-12-01

Fires play a major role in terrestrial ecosystems dynamics and the carbon cycle. Potential changes in fire regimes due to climate change, land use change, or human management could have substantial ecological, climatic and socio-economic impacts, and have recently been emphasized as a source of uncertainty for policy-makers and climate mitigation cost estimates. Anticipating these interactions thus entails interdisciplinary models. Here we describe the development of a new fire modeling framework, which features the essential integration of climatic, vegetation and anthropogenic drivers. The model is an attempt to realistically account for ignition, spread and termination processes, on a 12-hour time step and at 1 degree spatial resolution globally. Because the quantitative influence of fire drivers on these processes are often poorly constrained, the framework includes an optimization procedure whereby key parameters (e.g. influence of moisture on fire spread, probability of cloud-to-ground lightning flashes to actually ignite a fire, human ignition frequency as a function of land use density) are determined to maximize the agreement between modeled and observed burned area over the past decade. The model performs surprisingly well across all biomes, and shows good agreement on non-optimized features, such as seasonality and fire size, which suggests some potential for robust projections. We couple the model to an integrated assessment model and explore the consequences of mitigation policies, land use decisions and climate change on future fire regimes with a focus on the Amazon basin. The coupled model future projections show that business-as-usual land use expansion would increase the frequency of escaped fires in the remaining forest, especially when combined with models projecting a drier climate. Inversely, climate mitigation policies as projected in the IPCC RCP4.5 scenario achieve synergistic benefits, with increased forest extent, less fire ignitions, and higher moisture levels.

Signal Analysis of Automotive Engine Spark Ignition System using Case-Based Reasoning (CBR) and Case-based Maintenance (CBM)

NASA Astrophysics Data System (ADS)

Huang, H.; Vong, C. M.; Wong, P. K.

2010-05-01

With the development of modern technology, modern vehicles adopt electronic control system for injection and ignition. In traditional way, whenever there is any malfunctioning in an automotive engine, an automotive mechanic usually performs a diagnosis in the ignition system of the engine to check any exceptional symptoms. In this paper, we present a case-based reasoning (CBR) approach to help solve human diagnosis problem. Nevertheless, one drawback of CBR system is that the case library will be expanded gradually after repeatedly running the system, which may cause inaccuracy and longer time for the CBR retrieval. To tackle this problem, case-based maintenance (CBM) framework is employed so that the case library of the CBR system will be compressed by clustering to produce a set of representative cases. As a result, the performance (in retrieval accuracy and time) of the whole CBR system can be improved.

Mechanism of Start and Development of Aircraft Crash Fires

NASA Technical Reports Server (NTRS)

Pinkel, I. Irving; Preston, G. Merritt; Pesman, Gerard J.

1952-01-01

Full-scale aircraft crashes, devised to give surge fuel spillage and a high incidence of fire, were made to investigate the mechanism of the start and development of aircraft crash fires. The results are discussed. herein. This investigation revealed the characteristics of the ignition sources, the manner in which the combustibles spread., the mechanism of the union of the combustibles and ignition sources, and the pertinent factors governing the development of a crash fire as observed in this program.

Preliminary assessment of combustion modes for internal combustion wave rotors

NASA Technical Reports Server (NTRS)

Nalim, M. Razi

1995-01-01

Combustion within the channels of a wave rotor is examined as a means of obtaining pressure gain during heat addition in a gas turbine engine. Several modes of combustion are considered and the factors that determine the applicability of three modes are evaluated in detail; premixed autoignition/detonation, premixed deflagration, and non-premixed compression ignition. The last two will require strong turbulence for completion of combustion in a reasonable time in the wave rotor. The compression/autoignition modes will require inlet temperatures in excess of 1500 R for reliable ignition with most hydrocarbon fuels; otherwise, a supplementary ignition method must be provided. Examples of combustion mode selection are presented for two core engine applications that had been previously designed with equivalent 4-port wave rotor topping cycles using external combustion.

Novel characterization of capsule x-ray drive at the National Ignition Facility.

PubMed

MacLaren, S A; Schneider, M B; Widmann, K; Hammer, J H; Yoxall, B E; Moody, J D; Bell, P M; Benedetti, L R; Bradley, D K; Edwards, M J; Guymer, T M; Hinkel, D E; Hsing, W W; Kervin, M L; Meezan, N B; Moore, A S; Ralph, J E

2014-03-14

Indirect drive experiments at the National Ignition Facility are designed to achieve fusion by imploding a fuel capsule with x rays from a laser-driven hohlraum. Previous experiments have been unable to determine whether a deficit in measured ablator implosion velocity relative to simulations is due to inadequate models of the hohlraum or ablator physics. ViewFactor experiments allow for the first time a direct measure of the x-ray drive from the capsule point of view. The experiments show a 15%-25% deficit relative to simulations and thus explain nearly all of the disagreement with the velocity data. In addition, the data from this open geometry provide much greater constraints on a predictive model of laser-driven hohlraum performance than the nominal ignition target.

Stopping power in D6Li plasmas for target ignition studies

NASA Astrophysics Data System (ADS)

Cortez, Ross J.; Cassibry, Jason T.

2018-02-01

The ability to calculate the range of charged fusion products in a target is critical when estimating driver requirements. Additionally, charged particle ranges are a determining factor in the possibility that a burn front will propagate through the surrounding cold fuel layer, igniting the plasma. Performance parameters of the plasma, such as yield, gain, etc therefore rely on accurate knowledge of particle ranges and stopping power over a wide range of densities and temperatures. Further, this knowledge is essential in calculating ignition conditions for a given target design. In this paper, stopping power is calculated for DD and D6Li plasmas using a molecular dynamics based model. Emphasis is placed on solid D6Li which has been recently considered as a fuel option for fusion propulsion systems.

Hydrocarbon-Seeded Ignition System for Small Spacecraft Thrusters Using Ionic Liquid Propellants

NASA Technical Reports Server (NTRS)

Whitmore, Stephen A.; Merkley, Daniel P.; Eilers, Shannon D.; Taylor, Terry L.

2013-01-01

"Green" propellants based on Ionic-liquids (ILs) like Ammonium DiNitramide and Hydroxyl Ammonium Nitrate have recently been developed as reduced-hazard replacements for hydrazine. Compared to hydrazine, ILs offer up to a 50% improvement in available density-specific impulse. These materials present minimal vapor hazard at room temperature, and this property makes IL's potentially advantageous for "ride-share" launch opportunities where hazards introduced by hydrazine servicing are cost-prohibitive. Even though ILs present a reduced hazard compared to hydrazine, in crystalline form they are potentially explosive and are mixed in aqueous solutions to buffer against explosion. Unfortunately, the high water content makes IL-propellants difficult to ignite and currently a reliable "coldstart" capability does not exist. For reliable ignition, IL-propellants catalyst beds must be pre-heated to greater than 350 C before firing. The required preheat power source is substantial and presents a significant disadvantage for SmallSats where power budgets are extremely limited. Design and development of a "micro-hybrid" igniter designed to act as a "drop-in" replacement for existing IL catalyst beds is presented. The design requires significantly lower input energy and offers a smaller overall form factor. Unlike single-use "squib" pyrotechnic igniters, the system allows the gas generation cycle to be terminated and reinitiated on demand.

An Ozark fire history

Treesearch

Richard Guyette; Mavis Dey; Dan Dey

1999-01-01

Missouri's natural communities have been shaped by humans and wildland fires for thousands of years. In many ways, the history of fire in Missouri also is a history of human population, culture and migration. Fires caused by natural ignition, like lightning, are rare. Despite as many as 50 to 70 thunderstorm days per year, Conservation Department studies indicate...

Wildfire Policy in Mediterranean France: How Far is it Efficient and Sustainable?

PubMed

Curt, Thomas; Frejaville, Thibaut

2018-03-01

A new fire policy reinforcing aggressive fire suppression was established in Mediterranean France in response to the devastating wildfires of the 1990s, but to what extent this has changed fire activity yet remains poorly understood. For this purpose, we compared the number and location of ignitions and of burned areas between two 20-year periods (1975-1994 vs. 1995-2014), in parallel to the changes in fuel covering, human activity promoting ignitions, and fire weather. The number of fires decreased almost continuously since 1975, but sharply after 1994, suggesting an effect of better fire prevention due to the new policy. But the major change in fire activity is a considerable reduction in fire size and burned areas after 1994, especially during summer and in the most fire-prone places, in response to massive efforts put into fire suppression. These reductions have occurred while the covering by fuel biomass, the human pressure on ignition, and the fire weather index increased, thus making the study area more hazardous. Our results suggest that a strategy of aggressive fire suppression has great potential for counterbalancing the effects of climate changes and human activities and for controlling fire activity in the short term. However, we discuss whether such a suppression-oriented approach is sustainable in the context of global changes, which cast new fire challenges as demonstrated by the devastative fires of 2003 and 2016. We advocate for a more comprehensive fire policy to come. © 2017 Society for Risk Analysis.

Comparing fuel reduction treatments for reducing wildfire size and intensity in a boreal forest landscape of northeastern China.

PubMed

Wu, Zhiwei; He, Hong S; Liu, Zhihua; Liang, Yu

2013-06-01

Fuel load is often used to prioritize stands for fuel reduction treatments. However, wildfire size and intensity are not only related to fuel loads but also to a wide range of other spatially related factors such as topography, weather and human activity. In prioritizing fuel reduction treatments, we propose using burn probability to account for the effects of spatially related factors that can affect wildfire size and intensity. Our burn probability incorporated fuel load, ignition probability, and spread probability (spatial controls to wildfire) at a particular location across a landscape. Our goal was to assess differences in reducing wildfire size and intensity using fuel-load and burn-probability based treatment prioritization approaches. Our study was conducted in a boreal forest in northeastern China. We derived a fuel load map from a stand map and a burn probability map based on historical fire records and potential wildfire spread pattern. The burn probability map was validated using historical records of burned patches. We then simulated 100 ignitions and six fuel reduction treatments to compare fire size and intensity under two approaches of fuel treatment prioritization. We calibrated and validated simulated wildfires against historical wildfire data. Our results showed that fuel reduction treatments based on burn probability were more effective at reducing simulated wildfire size, mean and maximum rate of spread, and mean fire intensity, but less effective at reducing maximum fire intensity across the burned landscape than treatments based on fuel load. Thus, contributions from both fuels and spatially related factors should be considered for each fuel reduction treatment. Published by Elsevier B.V.

Astronaut Clothing for Exploration Missions

NASA Technical Reports Server (NTRS)

Poritz, Darwin H.; Orndoff, Evelyne; Kaspranskiy, Rustem R.; Schesinger, Thilini; Byrne, Vicky

2016-01-01

Astronaut clothes for exploration missions beyond low Earth orbit need to satisfy several challenges not met by the currently-used mostly-cotton clothing. A laundering system is not expected to be available, and thus soiled garments must be trashed. Jettisoning waste does not seem feasible at this time. The cabin oxygen concentration is expected to be higher than standard, and thus fabrics must better resist ignition and burning. Fabrics need to be identified that reduce logistical mass, that can be worn longer before disposal, that are at least as comfortable as cotton, and that resist ignition or that char immediately after ignition. Human factors and psychology indicate that crew well-being and morale require a variety of colors and styles to accommodate personal identity and preferences. Over the past four years, the Logistics Reduction Project under NASA's Advanced Exploration Systems Program has sponsored the Advanced Clothing System Task to conduct several ground studies and one ISS study. These studies have evaluated length of wear and personal preferences of commercially-available exercise- and routine-wear garments made from several fabrics (cotton, polyester, Merino wool, and modacrylic), woven and knitted. Note that Merino wool and modacrylic char like cotton in ambient air, while polyester unacceptably melts. This paper focuses on the two components of an International Space Station study, onboard and on the ground, with astronauts and cosmonauts. Fabrics were randomized to participants. Length of wear was assessed by statistical survival analysis, and preference by exact binomial confidence limits. Merino wool and modacrylic t-shirts were worn longer on average than polyester t-shirts. Interestingly, self-assessed preferences were inconsistent with length-of-wear behavior, as polyester was preferred to Merino wool and modacrylic.

40 CFR 89.117 - Test fleet selection.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES Emission Standards and... establishing deterioration factors, the manufacturer shall select the engines, subsystems, or components to be used to determine exhaust emission deterioration factors for each engine-family control system...

RL10 ignition limits test for Shuttle Centaur

NASA Technical Reports Server (NTRS)

1987-01-01

During routine development testing of the RL10A-3-3B engine a potential no-ignition condition was encountered when operating at certain propellant inlet conditions within the Shuttle Centaur G operating region. The conditions, the resulting investigative program, and methods to correct the potential problem are discussed. The Shuttle Centaur program was cancelled prior to completion of this effort. Although the RL10 engine in the Atlas Centaur vehicle is required by specification to operate over a wide range of propellant inlet conditions. The vehicle actually operates over a narrow range of conditions. This factor, combined with configuration differences between Atlas Centaur (or Titan Centaur) and the Shuttle Centaur RL10 engines, indicates the ignition problem does not exist for these vehicles. As a precautionary measure the vehicle manufacturer was requested to coordinate with Pratt and Whitney any anticipated changes in propellant inlet conditions from the current narrow range. An engineering change will be proposed for future RL10 deliveries to provide more consistent propellant flow to the igniter. This will permit operation of the engine throughout the wide range specification inlet conditions if desired.

Ignition and combustion characteristics of metallized propellants

NASA Technical Reports Server (NTRS)

Turns, S. R.; Mueller, D. C.; Scott, M. J.

1990-01-01

Research designed to develop detailed knowledge of the secondary atomization and ignition characteristics of aluminum slurry propellants was started. These processes are studied because they are the controlling factors limiting the combustion efficiency of aluminum slurry propellants in rocket applications. A burner and spray rig system allowing the study of individual slurry droplets having diameters from about 10 to 100 microns was designed and fabricated. The burner generates a near uniform high temperature environment from the merging of 72 small laminar diffusion flames above a honeycomb matrix. This design permits essentially adiabatic operation over a wide range of stoichiometries without danger of flashback. A single particle sizing system and velocimeter also were designed and assembled. Light scattered from a focused laser beam is related to the particle (droplet) size, while the particle velocity is determined by its transit time through the focal volume. Light from the combustion of aluminum is also sensed to determine if ignition was achieved. These size and velocity measurements will allow the determination of disruption and ignition times as functions of drop sizes and ambient conditions.

View Factor and Radiation-Hydrodynamic Simulations of Gas-Filled Outer-Quad-Only Hohlraums at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Young, Christopher; Meezan, Nathan; Landen, Otto

2017-10-01

A cylindrical National Ignition Facility hohlraum irradiated exclusively by NOVA-like outer quads (44 .5° and 50° beams) is proposed to minimize laser plasma interaction (LPI) losses and avoid problems with propagating the inner (23 .5° and 30°) beams. Symmetry and drive are controlled by shortening the hohlraum, using a smaller laser entrance hole (LEH), beam phasing the 44 .5° and 50° beams, and correcting the remaining P4 asymmetry with a capsule shim. Ensembles of time-resolved view factor simulations help narrow the design space of the new configuration, with fine tuning provided by the radiation-hydrodynamic code HYDRA. Prepared by LLNL under Contract DE-AC52-07NA27344.

Evaluation of Ignition and Burn Risk Associated with Contemporary Fiberoptic and Distal Sensor Endoscopic Technology.

PubMed

Spradling, Kyle; Uribe, Brittany; Okhunov, Zhamshid; Hofmann, Martin; Del Junco, Michael; Hwang, Christina; Gruber, Caden; Youssef, Ramy F; Landman, Jaime

2015-09-01

To evaluate the ignition and burn risk associated with contemporary fiberoptic and distal sensor endoscopic technologies. We used new and used SCB Xenon 300 light sources to illuminate a 4.8 mm fiberoptic cable, 10 mm laparoscope, 5 mm laparoscope, rigid cystoscope, semirigid ureteroscope, flexible cystoscope, flexible fiberoptic ureteroscope, distal sensor cystoscope, and a distal sensor ureteroscope (Karl Storz, Inc., Tuttlingen, Germany). We measured peak temperatures at the distal end of each device. We then evaluated each device on a flat and folded surgical drape to establish ignition risk. Finally, we evaluated the effects of all devices on human cadaver skin covered by surgical drape. Peak temperatures recorded for each device ranged from 26.9°C (flexible fiberoptic ureteroscope) to 194.5°C (fiberoptic cable). Drape ignition was noted when the fiberoptic cable was placed against a fold of drape. Contact with the fiberoptic cable, 10 mm laparoscope, 5 mm laparoscope, and distal sensor cystoscope resulted in cadaver skin damage. Cadaver skin damage occurred despite little or no visible change to the surgical drape. Rigid and flexible fiberoptic cystoscopes and flexible fiberoptic ureteroscopes had no effect on surgical drapes or cadaver skin. Fiberoptic light cables and some endoscopic devices have the potential to cause thermal injury and drape ignition. Thermal injury may occur without visible damage to drapes. Surgeons should remain vigilant regarding the risks associated with these devices and take necessary safety precautions to prevent patient injury.

Laser induced spark ignition of methane-oxygen mixtures

NASA Technical Reports Server (NTRS)

Santavicca, D. A.; Ho, C.; Reilly, B. J.; Lee, T.-W.

1991-01-01

Results from an experimental study of laser induced spark ignition of methane-oxygen mixtures are presented. The experiments were conducted at atmospheric pressure and 296 K under laminar pre-mixed and turbulent-incompletely mixed conditions. A pulsed, frequency doubled Nd:YAG laser was used as the ignition source. Laser sparks with energies of 10 mJ and 40 mJ were used, as well as a conventional electrode spark with an effective energy of 6 mJ. Measurements were made of the flame kernel radius as a function of time using pulsed laser shadowgraphy. The initial size of the spark ignited flame kernel was found to correlate reasonably well with breakdown energy as predicted by the Taylor spherical blast wave model. The subsequent growth rate of the flame kernel was found to increase with time from a value less than to a value greater than the adiabatic, unstretched laminar growth rate. This behavior was attributed to the combined effects of flame stretch and an apparent wrinkling of the flame surface due to the extremely rapid acceleration of the flame. The very large laminar flame speed of methane-oxygen mixtures appears to be the dominant factor affecting the growth rate of spark ignited flame kernels, with the mode of ignition having a small effect. The effect of incomplete fuel-oxidizer mixing was found to have a significant effect on the growth rate, one which was greater than could simply be accounted for by the effect of local variations in the equivalence ratio on the local flame speed.

The spatially varying influence of humans on fire probability in North America

Treesearch

Marc-Andre Parisien; Carol Miller; Sean A. Parks; Evan R. DeLancey; Francois-Nicolas Robinne; Mike D. Flannigan

2016-01-01

Humans affect fire regimes by providing ignition sources in some cases, suppressing wildfires in others, and altering natural vegetation in ways that may either promote or limit fire. InNorthAmerica, several studies have evaluated the effects of society on fire activity; however, most studies have been regional or subcontinental in scope and used different...

Exploring how alternative mapping approaches influence fireshed assessment and human community exposure to wildfire

Treesearch

Joe H. Scott; Matthew P. Thompson; Julie W. Gilbertson-Day

2015-01-01

Attaining fire-adapted human communities has become a key focus of collaborative planning on landscapes across the western United States and elsewhere. The coupling of fire simulation with GIS has expanded the analytical base to support such planning efforts, particularly through the "fireside" concept that identifies areas where wildfires could ignite and...

Compression-ignition Engine Performance at Altitudes and at Various Air Pressures and Temperatures

NASA Technical Reports Server (NTRS)

Moore, Charles S; Collins, John H

1937-01-01

Engine test results are presented for simulated altitude conditions. A displaced-piston combustion chamber on a 5- by 7-inch single cylinder compression-ignition engine operating at 2,000 r.p.m. was used. Inlet air temperature equivalent to standard altitudes up to 14,000 feet were obtained. Comparison between performance at altitude of the unsupercharged compression-ignition engine compared favorably with the carburetor engine. Analysis of the results for which the inlet air temperature, inlet air pressure, and inlet and exhaust pressure were varied indicates that engine performance cannot be reliably corrected on the basis of inlet air density or weight of air charge. Engine power increases with inlet air pressure and decreases with inlet air temperatures very nearly as straight line relations over a wide range of air-fuel ratios. Correction factors are given.

Microscopic modelling of ignition and burning for well-arranged energetic crystals in response to drop-weight impact

NASA Astrophysics Data System (ADS)

Wu, Yanqing; Huang, Fenglei; Zhou, Min

2014-05-01

To probe into impact sensitivity of energetic crystals, a theoretical approach was developed for modelling a single layer of energetic particles between upper striker and below base. Considering the particle plasticity, frictional heating, melting, fracture, and chemical reaction at particle level, effects of loading parameters and sample characteristics on time-to-ignition and burning rate were compared. Finite element numerical simulations were simultaneously performed to provide supporting evidence for thermo-mechanical interactions among energetic particles. Once hot- spots ignition occurred during impact, the macrokinetics of chemical reactions were formulated by hot-spots density, combustion wave velocity and geometric factor. The resulting reaction may or may not develop into a violent event, may be sustained or be extinguished, which can be revealed from the subsequent burn reaction rate.

Emission factors from different burning stages of agriculture wastes in Mexico.

PubMed

Santiago-De la Rosa, Naxieli; Mugica-Álvarez, Violeta; Cereceda-Balic, Francisco; Guerrero, Fabián; Yáñez, Karen; Lapuerta, Magin

2017-11-01

Open-air burning of agricultural wastes from crops like corn, rice, sorghum, sugar cane, and wheat is common practice in Mexico, which in spite limiting regulations, is the method to eliminate such wastes, to clear the land for further harvesting, to control grasses, weeds, insects, and pests, and to facilitate nutrient absorption. However, this practice generates air pollution and contributes to the greenhouse effect. Burning of straws derived from the said crops was emulated in a controlled combustion chamber, hence determining emission factors for particles, black carbon, carbon dioxide, carbon monoxide, and nitric oxide throughout the process, which comprised three apparent stages: pre-ignition, flaming, and smoldering. In all cases, maximum particle concentrations were observed during the flaming stage, although the maximum final contributions to the particle emission factors corresponded to the smoldering stage. The comparison between particle size distributions (from laser spectrometer) and black carbon (from an aethalometer) confirmed that finest particles were emitted mainly during the flaming stage. Carbon dioxide emissions were also highest during the flaming stage whereas those of carbon monoxide were highest during the smoldering stage. Comparing the emission factors for each straw type with their chemical analyses (elemental, proximate, and biochemical), some correlations were found between lignin content and particle emissions and either particle emissions or duration of the pre-ignition stage. High ash or lignin containing-straw slowed down the pre-ignition and flaming stages, thus favoring CO oxidation to CO 2 .

National direct-drive program on OMEGA and the National Ignition Facility

NASA Astrophysics Data System (ADS)

Goncharov, V. N.; Regan, S. P.; Campbell, E. M.; Sangster, T. C.; Radha, P. B.; Myatt, J. F.; Froula, D. H.; Betti, R.; Boehly, T. R.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Forrest, C. J.; Glebov, V. Yu; Harding, D. R.; Hu, S. X.; Igumenshchev, I. V.; Marshall, F. J.; McCrory, R. L.; Michel, D. T.; Seka, W.; Shvydky, A.; Stoeckl, C.; Theobald, W.; Gatu-Johnson, M.

2017-01-01

A major advantage of the laser direct-drive (DD) approach to ignition is the increased fraction of laser drive energy coupled to the hot spot and relaxed hot-spot requirements for the peak pressure and convergence ratios relative to the indirect-drive approach at equivalent laser energy. With the goal of a successful ignition demonstration using DD, the recently established national strategy has several elements and involves multiple national and international institutions. These elements include the experimental demonstration on OMEGA cryogenic implosions of hot-spot conditions relevant for ignition at MJ-scale energies available at the National Ignition Facility (NIF) and developing an understanding of laser-plasma interactions and laser coupling using DD experiments on the NIF. DD designs require reaching central stagnation pressures in excess of 100 Gbar. The current experiments on OMEGA have achieved inferred peak pressures of 56 Gbar (Regan et al 2016 Phys. Rev. Lett. 117 025001). Extensive analysis of the cryogenic target experiments and two- and three-dimensional simulations suggest that power balance, target offset, and target quality are the main limiting factors in target performance. In addition, cross-beam energy transfer (CBET) has been identified as the main mechanism reducing laser coupling. Reaching the goal of demonstrating hydrodynamic equivalence on OMEGA includes improving laser power balance, target position, and target quality at shot time. CBET must also be significantly reduced and several strategies have been identified to address this issue.

Progress towards ignition on the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edwards, M. J.; Patel, P. K.; Lindl, J. D.

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory includes a precision laser system now capable of delivering 1.8 MJ at 500 TW of 0.35-μm light to a target. NIF has been operational since March 2009. A variety of experiments have been completed in support of NIF's mission areas: national security, fundamental science, and inertial fusion energy. NIF capabilities and infrastructure are in place to support its missions with nearly 60 X-ray, optical, and nuclear diagnostic systems. A primary goal of the National Ignition Campaign (NIC) on the NIF was to implode a low-Z capsule filled with ∼0.2 mgmore » of deuterium-tritium (DT) fuel via laser indirect-drive inertial confinement fusion and demonstrate fusion ignition and propagating thermonuclear burn with a net energy gain of ∼5–10 (fusion yield/input laser energy). This requires assembling the DT fuel into a dense shell of ∼1000 g/cm{sup 3} with an areal density (ρR) of ∼1.5 g/cm{sup 2}, surrounding a lower density hot spot with a temperature of ∼10 keV and a ρR ∼0.3 g/cm{sup 2}, or approximately an α-particle range. Achieving these conditions demand precise control of laser and target parameters to allow a low adiabat, high convergence implosion with low ablator fuel mix. We have demonstrated implosion and compressed fuel conditions at ∼80–90% for most point design values independently, but not at the same time. The nuclear yield is a factor of ∼3–10× below the simulated values and a similar factor below the alpha dominated regime. This paper will discuss the experimental trends, the possible causes of the degraded performance (the off-set from the simulations), and the plan to understand and resolve the underlying physics issues.« less

A Survey of Studies on Ignition and Burn of Inertially Confined Fuels

NASA Astrophysics Data System (ADS)

Atzeni, Stefano

2016-10-01

A survey of studies on ignition and burn of inertial fusion fuels is presented. Potentials and issues of different approaches to ignition (central ignition, fast ignition, volume ignition) are addressed by means of simple models and numerical simulations. Both equimolar DT and T-lean mixtures are considered. Crucial issues concerning hot spot formation (implosion symmetry for central ignition; igniting pulse parameters for fast ignition) are briefly discussed. Recent results concerning the scaling of the ignition energy with the implosion velocity and constrained gain curves are also summarized.

Organic coal-water fuel: Problems and advances (Review)

NASA Astrophysics Data System (ADS)

Glushkov, D. O.; Strizhak, P. A.; Chernetskii, M. Yu.

2016-10-01

The study results of ignition of organic coal-water fuel (OCWF) compositions were considered. The main problems associated with investigation of these processes were identified. Historical perspectives of the development of coal-water composite fuel technologies in Russia and worldwide are presented. The advantages of the OCWF use as a power-plant fuel in comparison with the common coal-water fuels (CWF) were emphasized. The factors (component ratio, grinding degree of solid (coal) component, limiting temperature of oxidizer, properties of liquid and solid components, procedure and time of suspension preparation, etc.) affecting inertia and stability of the ignition processes of suspensions based on the products of coaland oil processing (coals of various types and metamorphism degree, filter cakes, waste motor, transformer, and turbine oils, water-oil emulsions, fuel-oil, etc.) were analyzed. The promising directions for the development of modern notions on the OCWF ignition processes were determined. The main reasons limiting active application of the OCWF in power generation were identified. Characteristics of ignition and combustion of coal-water and organic coal-water slurry fuels were compared. The effect of water in the composite coal fuels on the energy characteristics of their ignition and combustion, as well as ecological features of these processes, were elucidated. The current problems associated with pulverization of composite coal fuels in power plants, as well as the effect of characteristics of the pulverization process on the combustion parameters of fuel, were considered. The problems hindering the development of models of ignition and combustion of OCWF were analyzed. It was established that the main one was the lack of reliable experimental data on the processes of heating, evaporation, ignition, and combustion of OCWF droplets. It was concluded that the use of high-speed video recording systems and low-inertia sensors of temperature and gas concentration could help in providing the lacking experimental information.

14 CFR 27.1145 - Ignition switches.

Code of Federal Regulations, 2014 CFR

2014-01-01

... master ignition control. (b) Each group of ignition switches, except ignition switches for turbine engines for which continuous ignition is not required, and each master ignition control must have a means... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 27.1145 Ignition...

14 CFR 27.1145 - Ignition switches.

Code of Federal Regulations, 2012 CFR

2012-01-01

... master ignition control. (b) Each group of ignition switches, except ignition switches for turbine engines for which continuous ignition is not required, and each master ignition control must have a means... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 27.1145 Ignition...

14 CFR 27.1145 - Ignition switches.

Code of Federal Regulations, 2010 CFR

2010-01-01

... master ignition control. (b) Each group of ignition switches, except ignition switches for turbine engines for which continuous ignition is not required, and each master ignition control must have a means... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 27.1145 Ignition...

14 CFR 27.1145 - Ignition switches.

Code of Federal Regulations, 2011 CFR

2011-01-01

... master ignition control. (b) Each group of ignition switches, except ignition switches for turbine engines for which continuous ignition is not required, and each master ignition control must have a means... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 27.1145 Ignition...

14 CFR 27.1145 - Ignition switches.

Code of Federal Regulations, 2013 CFR

2013-01-01

... master ignition control. (b) Each group of ignition switches, except ignition switches for turbine engines for which continuous ignition is not required, and each master ignition control must have a means... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 27.1145 Ignition...

Signal Analysis of Automotive Engine Spark Ignition System using Case-Based Reasoning (CBR) and Case-based Maintenance (CBM)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, H.; Vong, C. M.; Wong, P. K.

2010-05-21

With the development of modern technology, modern vehicles adopt electronic control system for injection and ignition. In traditional way, whenever there is any malfunctioning in an automotive engine, an automotive mechanic usually performs a diagnosis in the ignition system of the engine to check any exceptional symptoms. In this paper, we present a case-based reasoning (CBR) approach to help solve human diagnosis problem. Nevertheless, one drawback of CBR system is that the case library will be expanded gradually after repeatedly running the system, which may cause inaccuracy and longer time for the CBR retrieval. To tackle this problem, case-based maintenancemore » (CBM) framework is employed so that the case library of the CBR system will be compressed by clustering to produce a set of representative cases. As a result, the performance (in retrieval accuracy and time) of the whole CBR system can be improved.« less

Sensitivity of combustion and ignition characteristics of the solid-fuel charge of the microelectromechanical system of a microthruster to macrokinetic and design parameters

NASA Astrophysics Data System (ADS)

Futko, S. I.; Ermolaeva, E. M.; Dobrego, K. V.; Bondarenko, V. P.; Dolgii, L. N.

2012-07-01

We have developed a sensitivity analysis permitting effective estimation of the change in the impulse responses of a microthrusters and in the ignition characteristics of the solid-fuel charge caused by the variation of the basic macrokinetic parameters of the mixed fuel and the design parameters of the microthruster's combustion chamber. On the basis of the proposed sensitivity analysis, we have estimated the spread of both the propulsive force and impulse and the induction period and self-ignition temperature depending on the macrokinetic parameters of combustion (pre-exponential factor, activation energy, density, and heat content) of the solid-fuel charge of the microthruster. The obtained results can be used for rapid and effective estimation of the spread of goal functions to provide stable physicochemical characteristics and impulse responses of solid-fuel mixtures in making and using microthrusters.

Measurements of Reduced Hydrodynamic Instability Growth in Adiabat Shaped Implosions at the NIF

NASA Astrophysics Data System (ADS)

Casey, Daniel; Macphee, Andrew; Milovich, Jose; Smalyuk, Vladimir; Clark, Dan; Robey, Harry; Peterson, Luc; Baker, Kevin; Weber, Chris

2015-11-01

Hydrodynamic instabilities can cause capsule defects and other perturbations to grow and degrade implosion performance in ignition experiments at the National Ignition Facility (NIF). Radiographic measurements of ablation front perturbation growth were performed using adiabat-shaped drives which are shown to have lower ablation front growth than the low foot drive. This is partly due to faster Richtmyer-Meshkov (RM) oscillations during the shock transit phase of the implosion moving the node in the growth factor spectrum to lower mode numbers reducing the peak growth amplitude. This is demonstrated experimentally by a reversal of the perturbation phase at higher mode numbers (120-160). These results show that the ablation front growth and fuel adiabat can be controlled somewhat-independently and are providing insight into new, more stable, ignition designs. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

OH PLIF measurement in a spark ignition engine with a tumble flow

NASA Astrophysics Data System (ADS)

Kumar, Siddhartha; Moronuki, Tatsuya; Shimura, Masayasu; Minamoto, Yuki; Yokomori, Takeshi; Tanahashi, Mamoru; Strategic Innovation Program (SIP) Team

2017-11-01

Under lean conditions, high compression ratio and strong tumble flow; cycle-to-cycle variations of combustion in spark ignition (SI) engines is prominent, therefore, relation between flame propagation characteristics and increase of pressure needs to be clarified. The present study is aimed at exploring the spatial and temporal development of the flame kernel using OH planar laser-induced fluorescence (OH PLIF) in an optical SI engine. Equivalence ratio is changed at a fixed indicated mean effective pressure of 400 kPa. From the measurements taken at different crank angle degrees (CAD) after ignition, characteristics of flame behavior were investigated considering temporal evolution of in-cylinder pressure, and factors causing cycle-to-cycle variations are discussed. In addition, the effects of tumble flow intensity on flame propagation behavior were also investigated. This work is supported by the Cross-ministerial Strategic Innovation Program (SIP), `Innovative Combustion Technology'.

Ignition characterization of LOX/hydrocarbon propellants

NASA Technical Reports Server (NTRS)

Lawver, B. R.; Rousar, D. C.; Wong, K. Y.

1985-01-01

The results of an evaluation of the ignition characteristics of the gaseous oxygen (Gox)/Ethanol propellant combination are presented. Ignition characterization was accomplished through the analysis, design, fabrication and testing of a spark initiated torch igniter and prototype 620 lbF thruster/igniter assembly. The igniter was tested over a chamber pressure range of 74 to 197 psia and mixture ratio range of 0.778 to 3.29. Cold (-92 to -165 F) and ambient (44 to 80 F) propellant temperatures were used. Spark igniter ignition limits and thruster steady state and pulse mode, performance, cooling and stability data are presented. Spark igniter ignition limits are presented in terms of cold flow pressure, ignition chamber diameter and mixture ratio. Thruster performance is presented in terms of vacuum specific impulse versus engine mixture ratio. Gox/Ethanol propellants were shown to be ignitable over a wide range of mixture ratios. Cold propellants were shown to have a minor effect on igniter ignition limits. Thruster pulse mode capability was demonstrated with multiple pulses of 0.08 sec duration and less.

Final Report - Low Temperature Combustion Chemistry And Fuel Component Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wooldridge, Margaret

Recent research into combustion chemistry has shown that reactions at “low temperatures” (700 – 1100 K) have a dramatic influence on ignition and combustion of fuels in virtually every practical combustion system. A powerful class of laboratory-scale experimental facilities that can focus on fuel chemistry in this temperature range is the rapid compression facility (RCF), which has proven to be a versatile tool to examine the details of fuel chemistry in this important regime. An RCF was used in this project to advance our understanding of low temperature chemistry of important fuel compounds. We show how factors including fuel molecularmore » structure, the presence of unsaturated C=C bonds, and the presence of alkyl ester groups influence fuel auto-ignition and produce variable amounts of negative temperature coefficient behavior of fuel ignition. We report new discoveries of synergistic ignition interactions between alkane and alcohol fuels, with both experimental and kinetic modeling studies of these complex interactions. The results of this project quantify the effects of molecular structure on combustion chemistry including carbon bond saturation, through low temperature experimental studies of esters, alkanes, alkenes, and alcohols.« less

Lots of lightning and plenty of people: An ecological history of fire in the upland southwest

USGS Publications Warehouse

Allen, Craig D.; Vale, Thomas R.

2002-01-01

Was the pre-European Southwest a region of wild landscapes, shaped primarily by natural processes like lightning-ignited fire, or did people substantially mold these lands into regional-scale artifacts through their use of fire and other means? Perspectives on this question have varied markedly through time and between scholars, as evident from the quotes interspersed through this chapter (see Box 5.1.). As the American frontier closed around the turn of the nineteenth century, lightning was rarely considered a primary cause of fire, with most fires in western forests assumed to be human-ignited. Native Americans were thought to have been the primary source of burning in the Southwest until EuroAmericans usurped that role after ca. 1850. Today, lightning-ignited fire is widely acknowledged to be an ancient and essential ecological process in the American Southwest (Pyne 1995a:282-283; Swetnam and Baisan 1996a; Bogan et al. 1998), for millennia structuring landscapes from low-elevation desert grasslands to montane forests. However, because the Southwest has been home to people for more than 12,000 years, with large human populations for over 1,000 years (Plog et al. 1988), some scholars continue to assert the dominance of aboriginal burning in the fire regimes of this region (Dobyns 1981; Pyne 1995a, 1996, 1997). This essay focuses on the roles of  

40 CFR 1045.245 - How do I determine deterioration factors from exhaust durability testing?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false How do I determine deterioration factors from exhaust durability testing? 1045.245 Section 1045.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.520 - What testing must I perform to establish deterioration factors?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false What testing must I perform to establish deterioration factors? 1045.520 Section 1045.520 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.520 - What testing must I perform to establish deterioration factors?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false What testing must I perform to establish deterioration factors? 1045.520 Section 1045.520 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.245 - How do I determine deterioration factors from exhaust durability testing?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 33 2011-07-01 2011-07-01 false How do I determine deterioration factors from exhaust durability testing? 1045.245 Section 1045.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.520 - What testing must I perform to establish deterioration factors?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false What testing must I perform to establish deterioration factors? 1045.520 Section 1045.520 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.520 - What testing must I perform to establish deterioration factors?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false What testing must I perform to establish deterioration factors? 1045.520 Section 1045.520 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.520 - What testing must I perform to establish deterioration factors?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 33 2011-07-01 2011-07-01 false What testing must I perform to establish deterioration factors? 1045.520 Section 1045.520 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.245 - How do I determine deterioration factors from exhaust durability testing?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false How do I determine deterioration factors from exhaust durability testing? 1045.245 Section 1045.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.245 - How do I determine deterioration factors from exhaust durability testing?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false How do I determine deterioration factors from exhaust durability testing? 1045.245 Section 1045.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.245 - How do I determine deterioration factors from exhaust durability testing?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false How do I determine deterioration factors from exhaust durability testing? 1045.245 Section 1045.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

Present Status and Prospects of FIREX Project

NASA Astrophysics Data System (ADS)

Mima, K.

2008-07-01

The goal of the first phase of Fast Ignition Realization EXperiment (FIREX) project (FIREX-I) is to demonstrate ignition temperature of 5-10 keV, followed by the second phase to demonstrate ignition and burn. Since starting FIREX-I project, plasma physics study in ILE has been devoted to increase the coupling efficiency and to improve compression performance. The heating efficiency can be increased by the following two ways. 1) A previous experiments indicate that the coupling of heating laser to imploded plasmas increases with coating a low-density. foam used in the experiment, low-Z plastic foam is desired for efficient electron transport. (Lei et al. 2006). 2) Electrons generated in the inner surface of the double cone will return by sheathe potential generated between two cones. A 2-D PIC simulation indicates that hot electron confinement is improved by a factor of 1.7 (Nakamura et al. 2007). Further optimization of cone geometry by 2-D simulation will be presented in the workshop. The implosion performance can be improved by three ways. 1) Low-Z plastic layer coating on the outer surface of the cone: The 2D hydro-simulation PINOCO predicts that the target areal density increases by a factor of 2. 2) Br doped plastic layer on a fuel pellet may significantly moderate the Rayleigh-Taylor instability (Fujioka et al. 2004), making implosion more stable. 3) Reducing vapor gas pressure in a pellet is necessary to suppress strength of a jet that will destroy the cone tip. (Stephens et al. 2005). As for the cryogenic target fabrication, R&D of fabricating foam cryogenic cine shell target are under development by the joint group between Osaka Univ. and NIFS. The amplifier system of the heating laser LFEX is completed in March 2008. The amplification test has demonstrated laser energy of 3 kJ/beam at 3nm bandwidth. The equivalent 12 kJ in 4 beams meets the specification of LFEX. The large tiled gratings for pulse compressor are completed and installed. The short pulse laser will be delivered on a target in September, 2008. The fully integrated fast ignition experiments is scheduled on February 2009 until the end of 2010. If subsequent FIREX-II will start as proposed, the ignition and burn will be demonstrated in parallel to that at NIF and LMJ, providing a scientific database of both central and fast ignition.

Laser ignition of an experimental combustion chamber with a multi-injector configuration at low pressure conditions

NASA Astrophysics Data System (ADS)

Börner, Michael; Manfletti, Chiara; Kroupa, Gerhard; Oschwald, Michael

2017-09-01

In search of reliable and light-weight ignition systems for re-ignitable upper stage engines, a laser ignition system was adapted and tested on an experimental combustion chamber for propellant injection into low combustion chamber pressures at 50-80 mbar. The injector head pattern consisted of five coaxial injector elements. Both, laser-ablation-driven ignition and laser-plasma-driven ignition were tested for the propellant combination liquid oxygen and gaseous hydrogen. The 122 test runs demonstrated the reliability of the ignition system for different ignition configurations and negligible degradation due to testing. For the laser-plasma-driven scheme, minimum laser pulse energies needed for 100% ignition probability were found to decrease when increasing the distance of the ignition location from the injector faceplate with a minimum of 2.6 mJ. For laser-ablation-driven ignition, the minimum pulse energy was found to be independent of the ablation material tested and was about 1.7 mJ. The ignition process was characterized using both high-speed Schlieren and OH* emission diagnostics. Based on these findings and on the increased fiber-based pulse transport capabilities recently published, new ignition system configurations for space propulsion systems relying on fiber-based pulse delivery are formulated. If the laser ignition system delivers enough pulse energy, the laser-plasma-driven configuration represents the more versatile configuration. If the laser ignition pulse power is limited, the application of laser-ablation-driven ignition is an option to realize ignition, but implies restrictions concerning the location of ignition.

Progress of studies on preparation of TiO2 photocatalysts with sol-gel auto igniting synthesis

NASA Astrophysics Data System (ADS)

Wu, Di; Shi, Zaifeng; Zhang, Xiaopeng; Xinghui, Wu

2017-11-01

In this article, influencing factors on the kinetics of the process of Sol-gel Auto igniting Synthesis (SAS) which is an advanced technology for preparing nanometer particles of inorganic materials were reviewed. The studies on preparing of nanometer TiO2 photocatalysts with SAS were focused. It was concluded that SAS will play an important role in practical preparing of high-pure nanometer TiO2 powder, and as a technical support, preparation of titania TiO2 from titanic iron ore with SAS is feasible and practicable.

Spacecraft Fire Safety: A Human Space Flight Program Perspective

NASA Technical Reports Server (NTRS)

Pedley, Michael D.

2003-01-01

This paper presents viewgraphs on the International Space Station's fire safety program from a human space flight perspective. The topics include: 1) Typical Manned Spacecraft Materials; 2) Typical Flammable Hardware Protection; 3) Materials Flammability; 4) Fire Retardants; 5) Nonflammable Foam Cushion Material; 6) Electrical Wire and Cable; 7) Russian Solid-Fuel Oxygen Generator (SFOG); 8) GOX Ignition Mechanisms; 9) Fire Detection; and 10) Fire Suppression.

14 CFR 23.1145 - Ignition switches.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1145 Ignition switches. (a) Ignition switches must control and shut off each ignition circuit... the grouping of switches or by a master ignition control. (c) Each group of ignition switches, except...

14 CFR 23.1145 - Ignition switches.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1145 Ignition switches. (a) Ignition switches must control and shut off each ignition circuit... the grouping of switches or by a master ignition control. (c) Each group of ignition switches, except...

14 CFR 23.1145 - Ignition switches.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1145 Ignition switches. (a) Ignition switches must control and shut off each ignition circuit... the grouping of switches or by a master ignition control. (c) Each group of ignition switches, except...

14 CFR 23.1145 - Ignition switches.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1145 Ignition switches. (a) Ignition switches must control and shut off each ignition circuit... the grouping of switches or by a master ignition control. (c) Each group of ignition switches, except...

14 CFR 23.1145 - Ignition switches.

Code of Federal Regulations, 2013 CFR

2013-01-01

... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 23.1145 Ignition switches. (a) Ignition switches must control and shut off each ignition circuit... the grouping of switches or by a master ignition control. (c) Each group of ignition switches, except...

Experimental Investigation of Piston Heat Transfer in a Light Duty Engine Under Conventional Diesel, Homogeneous Charge Compression Ignition, and Reactivity Controlled Compression Ignition Combustion Regimes

DTIC Science & Technology

2014-01-15

in a Light Duty Engine Under Conventional Diesel, Homogeneous Charge Compression Ignition , and Reactivity Controlled Compression Ignition ...Conventional Diesel (CDC), Homogeneous Charge Compression Ignition (HCCI), and Reactivity Controlled Compression Ignition (RCCI) combustion...LTC) regimes, including reactivity controlled compression ignition (RCCI), partially premixed combustion (PPC), and homogenous charge compression

Validating hydrodynamic growth in National Ignition Facility implosions

DOE PAGES

Peterson, J. L.; Casey, D. T.; Hurricane, O. A.; ...

2015-05-12

We present new hydrodynamic growth experiments at the National Ignition Facility, which extend previous measurements up to Legendre mode 160 and convergence ratio 4, continuing the growth factor dispersion curve comparison of the low foot and high foot pulses reported by Casey et al. [Phys. Rev. E 90, 011102(R) (2014)]. We show that the high foot pulse has lower growth factor and lower growth rate than the low foot pulse. Using novel on-capsule fiducial markers, we observe that mode 160 inverts sign (changes phase) for the high foot pulse, evidence of amplitude oscillations during the Richtmyer-Meshkov phase of a sphericallymore » convergent system. Post-shot simulations are consistent with the experimental measurements for all but the shortest wavelength perturbations, reinforcing the validity of radiation hydrodynamic simulations of ablation front growth in inertial confinement fusion capsules.« less

Differences in Human Versus Lightning Fires with Human Proximity at Two Spatial Scales in Interior Alaska

NASA Astrophysics Data System (ADS)

Calef, M. P.; Varvak, A.; McGuire, A. D.

2017-12-01

The boreal forest contains significant amounts of carbon in its biomass and soils and is currently responding to a rapidly changing climate. This is leading to warmer temperatures, drier conditions and larger and more frequent wildfires in western North America. However, the fire regime is also affected by direct human activities through suppression, ignition, and land use changes. Models are important predictive tools for understanding future conditions but they are based on regional generalizations of wildfire behavior and do not account for the complexity of human-fire interactions. In order to achieve a better understanding of the human influence on fires and how human fires differ from lightning fires, we analyzed both in regard to human proximity at two spatial scales (the Fairbanks subregion and Interior Alaska) using ArcGIS and quantitative analysis methods. We found that area burned is increasing across the region at 3% per year and is driven by increase in area burned by lightning while human-caused area burned has been decreasing recently especially in the WUI near Fairbanks. Human fires differed from lightning fires in several ways: they occurred significantly closer to settlements and highways, burned for a shorter duration, and were not as restricted to a brief seasonal window. The fire regime in the much more populated Fairbanks subregion has been altered by human activity: it experienced substantially more human fire ignitions along with a larger area burned though the human influence decreases with distance. This study provides important insights into spatial patterns of human influences on fires and provides useful information for fire modeling and fire management.

Molded composite pyrogen igniter for rocket motors. [solid propellant ignition

NASA Technical Reports Server (NTRS)

Heier, W. C.; Lucy, M. H. (Inventor)

1978-01-01

A lightweight pyrogen igniter assembly including an elongated molded plastic tube adapted to contain a pyrogen charge was designed for insertion into a rocket motor casing for ignition of the rocket motor charge. A molded plastic closure cap provided for the elongated tube includes an ignition charge for igniting the pyrogen charge and an electrically actuated ignition squib for igniting the ignition charge. The ignition charge is contained within a portion of the closure cap, and it is retained therein by a noncorrosive ignition pellet retainer or screen which is adapted to rest on a shoulder of the elongated tube when the closure cap and tube are assembled together. A circumferentially disposed metal ring is provided along the external circumference of the closure cap and is molded or captured within the plastic cap in the molding process to provide, along with O-ring seals, a leakproof rotary joint.

The effect of kerosene injection on ignition probability of local ignition in a scramjet combustor

NASA Astrophysics Data System (ADS)

Bao, Heng; Zhou, Jin; Pan, Yu

2017-03-01

The spark ignition of kerosene is investigated in a scramjet combustor with a flight condition of Ma 4, 17 km. Based plentiful of experimental data, the ignition probabilities of the local ignition have been acquired for different injection setups. The ignition probability distributions show that the injection pressure and injection location have a distinct effect on spark ignition. The injection pressure has both upper and lower limit for local ignition. Generally, the larger mass flow rate will reduce the ignition probability. The ignition position also affects the ignition near the lower pressure limit. The reason is supposed to be the cavity swallow effect on upstream jet spray near the leading edge, which will make the cavity fuel rich. The corner recirculation zone near the front wall of the cavity plays a significant role in the stabilization of local flame.

LOX/Methane Main Engine Igniter Tests and Modeling

NASA Technical Reports Server (NTRS)

Breisacher, Kevin J.; Ajmani, Kumund

2008-01-01

The LOX/methane propellant combination is being considered for the Lunar Surface Access Module ascent main engine propulsion system. The proposed switch from the hypergolic propellants used in the Apollo lunar ascent engine to LOX/methane propellants requires the development of igniters capable of highly reliable performance in a lunar surface environment. An ignition test program was conducted that used an in-house designed LOX/methane spark torch igniter. The testing occurred in Cell 21 of the Research Combustion Laboratory to utilize its altitude capability to simulate a space vacuum environment. Approximately 750 ignition test were performed to evaluate the effects of methane purity, igniter body temperature, spark energy level and frequency, mixture ratio, flowrate, and igniter geometry on the ability to obtain successful ignitions. Ignitions were obtained down to an igniter body temperature of approximately 260 R with a 10 torr back-pressure. The data obtained is also being used to anchor a CFD based igniter model.

14 CFR 25.1145 - Ignition switches.

Code of Federal Regulations, 2013 CFR

2013-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 25.1145 Ignition switches. (a) Ignition switches must control each engine ignition circuit on each engine. (b) There must be means to quickly shut off all ignition by the grouping of switches or by a master ignition control. (c...

14 CFR 29.1145 - Ignition switches.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 29.1145 Ignition switches. (a) Ignition switches must control each ignition circuit on each engine. (b) There must be means to quickly shut off all ignition by the grouping of switches or by a master ignition control. (c...

14 CFR 25.1145 - Ignition switches.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 25.1145 Ignition switches. (a) Ignition switches must control each engine ignition circuit on each engine. (b) There must be means to quickly shut off all ignition by the grouping of switches or by a master ignition control. (c...

14 CFR 23.1165 - Engine ignition systems.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Controls and Accessories § 23.1165 Engine ignition systems. (a) Each battery ignition system must be... ignition. (e) Each turbine engine ignition system must be independent of any electrical circuit that is not... commuter category airplanes, each turbine engine ignition system must be an essential electrical load. [Doc...

14 CFR 29.1145 - Ignition switches.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 29.1145 Ignition switches. (a) Ignition switches must control each ignition circuit on each engine. (b) There must be means to quickly shut off all ignition by the grouping of switches or by a master ignition control. (c...

14 CFR 25.1145 - Ignition switches.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 25.1145 Ignition switches. (a) Ignition switches must control each engine ignition circuit on each engine. (b) There must be means to quickly shut off all ignition by the grouping of switches or by a master ignition control. (c...

14 CFR 29.1145 - Ignition switches.

Code of Federal Regulations, 2013 CFR

2013-01-01

... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 29.1145 Ignition switches. (a) Ignition switches must control each ignition circuit on each engine. (b) There must be means to quickly shut off all ignition by the grouping of switches or by a master ignition control. (c...

14 CFR 25.1145 - Ignition switches.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 25.1145 Ignition switches. (a) Ignition switches must control each engine ignition circuit on each engine. (b) There must be means to quickly shut off all ignition by the grouping of switches or by a master ignition control. (c...

14 CFR 29.1145 - Ignition switches.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 29.1145 Ignition switches. (a) Ignition switches must control each ignition circuit on each engine. (b) There must be means to quickly shut off all ignition by the grouping of switches or by a master ignition control. (c...

14 CFR 25.1145 - Ignition switches.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 25.1145 Ignition switches. (a) Ignition switches must control each engine ignition circuit on each engine. (b) There must be means to quickly shut off all ignition by the grouping of switches or by a master ignition control. (c...

14 CFR 23.1165 - Engine ignition systems.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Controls and Accessories § 23.1165 Engine ignition systems. Link to an amendment published at 76 FR 75759... discharge of any battery used for engine ignition. (e) Each turbine engine ignition system must be... ignition systems. (f) In addition, for commuter category airplanes, each turbine engine ignition system...

14 CFR 29.1145 - Ignition switches.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Powerplant Controls and Accessories § 29.1145 Ignition switches. (a) Ignition switches must control each ignition circuit on each engine. (b) There must be means to quickly shut off all ignition by the grouping of switches or by a master ignition control. (c...

Spontaneous human combustion in the light of the 21st century.

PubMed

Koljonen, Virve; Kluger, Nicolas

2012-01-01

The term "spontaneous human combustion" refers to a situation when a human body is found with significant portions of the middle parts of the body reduced to ashes, much less damage to the head and extremities, and minimal damage to the direct surroundings of the body. Typically, no observable source of ignition is found in the vicinity of the victim and a bad smelling oily substance is noted. In the past, such a situation was erroneously attributed to supernatural powers, as such phenomenon occurs in the absence of any witness. The purpose of this review article was to analyze articles published from January 1, 2000, on this unique type of burn injury. Further aims were to gather and present data on the causes and events leading to this situation. The literature was reviewed with PubMed interface using the key words spontaneous human combustion and preternatural combustion. Specific inclusion criteria resulted in 12 patients. A unique sequence of events takes place for the human body to incinerate to ashes. The flame burn victim has to die for the body fat to start melting. A tear in the skin has to occur for the melted fat to impregnate the charred clothes, igniting a wick effect that produces localized heat for extended period. A phenomenon called spontaneous human combustion is reality. The term "spontaneous human combustion" has nuances which are not applicable to this situation or to these modern times, therefore we suggest a new term "fat wick burns."

40 CFR 265.17 - General requirements for ignitable, reactive, or incompatible wastes.

Code of Federal Regulations, 2011 CFR

2011-07-01

... to prevent accidental ignition or reaction of ignitable or reactive waste. This waste must be separated and protected from sources of ignition or reaction including but not limited to: Open flames...), spontaneous ignition (e.g., from heat-producing chemical reactions), and radiant heat. While ignitable or...

40 CFR 265.17 - General requirements for ignitable, reactive, or incompatible wastes.

Code of Federal Regulations, 2010 CFR

2010-07-01

... to prevent accidental ignition or reaction of ignitable or reactive waste. This waste must be separated and protected from sources of ignition or reaction including but not limited to: Open flames...), spontaneous ignition (e.g., from heat-producing chemical reactions), and radiant heat. While ignitable or...

Program design for incentivizing ignition interlock installation for alcohol-impaired drivers: The Ontario approach.

PubMed

Ma, Tracey; Byrne, Patrick A; Bhatti, Junaid A; Elzohairy, Yoassry

2016-10-01

Drinking and driving is a major risk factor for traffic injuries. Although ignition interlocks reduce drinking and driving while installed, several issues undermine their implementation including delayed eligibility for installation, low installation once eligible, and a return to previous risk levels after de-installation. The Canadian province of Ontario introduced a "Reduced Suspension with Ignition Interlock Conduct Review" Program, significantly changing pre-existing interlock policy. The Program incentivizes interlock installation and an "early" guilty plea. It also attempts to reduce long-term recidivism through behavioural feedback and compliance-based removal. This evaluation is the first in assessing Program impact. Ontario drivers with a first time alcohol-impaired driving conviction between July 1, 2005 and November 25, 2014 comprised the study cohort. Longitudinal analyses, using interrupted time series and Cox regression, were conducted in which exposure was the Program and the outcomes were ignition interlock installation (N=30,200), pre-trial elapsed time (N=30,200), and post-interlock recidivism (N=9326). After Program implementation, installation rates increased by 54% and pre-trial elapsed time decreased by 146 days. Results suggest no effect on post-interlock recidivism. Through an incentive-based design, this Program was effective at addressing two commonly cited barriers to interlock implementation- delayed eligibility for installation and low installation once eligible. Results reveal that installation rates are responsive not only to incentivization but also to other external factors, thus presenting an opportunity for policy makers to find unique ways to influence interlock uptake, and thereby, to extend their deterrent effects to a larger subset of the population. This study is one of the few that do not rely on proxy measures of installation rate. Copyright © 2016 Crown. Published by Elsevier Ltd.. All rights reserved.

Investigations of the small-scale thermal behavior of sol-gel thermites.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warren, Mial E.; Farrow, Matthew; Tappan, Alexander Smith

2009-02-01

Sol-gel thermites, formulated from nanoporous oxides and dispersed fuel particles, may provide materials useful for small-scale, intense thermal sources, but understanding the factors affecting performance is critical prior to use. Work was conducted on understanding the synthesis conditions, thermal treatments, and additives that lead to different performance characteristics in iron oxide sol-gel thermites. Additionally, the safety properties of sol-gel thermites were investigated, especially those related to air sensitivity. Sol-gel thermites were synthesized using a variety of different techniques and there appear to be many viable routes to relatively equivalent thermites. These thermites were subjected to several different thermal treatments undermore » argon in a differential scanning calorimeter, and it was shown that a 65 C hold for up to 200 minutes was effective for the removal of residual solvent, thus preventing boiling during the final thermal activation step. Vacuum-drying prior to this heating was shown to be even more effective at removing residual solvent. The addition of aluminum and molybdenum trioxide (MoO{sub 3}) reduced the total heat release per unit mass upon exposure to air, probably due to a decrease in the amount of reduced iron oxide species in the thermite. For the thermal activation step of heat treatment, three different temperatures were investigated. Thermal activation at 200 C resulted in increased ignition sensitivity over thermal activation at 232 C, and thermal activation at 300 C resulted in non-ignitable material. Non-sol-gel iron oxide did not exhibit any of the air-sensitivity observed in sol-gel iron oxide. In the DSC experiments, no bulk ignition of sol-gel thermites was observed upon exposure to air after thermal activation in argon; however ignition did occur when the material was heated in air after thermal treatment. In larger-scale experiments, up to a few hundred milligrams, no ignition was observed upon exposure to air after thermal activation in vacuum; however ignition by resistively-heated tungsten wire was possible. Thin films of thermite were fabricated using a dispersed mixture of aluminum and iron oxide particles, but ignition and propagation of these films was difficult. The only ignition and propagation observed was in a preheated sample.« less

Evidence of Ice Age humans in Beringia: new insights on the peopling of the Americas

NASA Astrophysics Data System (ADS)

Vachula, R. S.; Longo, W. M.; Daniels, W.; Dee, S.; Russell, J. M.; Huang, Y.

2017-12-01

The American continents were the final frontier of the global proliferation of Homo sapiens. The Bering Land Bridge that once connected Eurasia and North America, is widely accepted as the corridor for this human migration. However, the timeline, pathway, and environmental impact of human arrival to these previously unpeopled lands remain contentious in part due to a sparsity of physical archaeological or paleoenvironmental evidence. Recent conflicting genetic evidence suggests that humans lived in Beringia for an extended period of time (ca. 15,000 years) and did not diverge from Asian populations prior to 23,000 years before present (BP). The genetic evidence lacks supporting physical data, is prone to uncertainties inherent to molecular clocks, and thus further occludes our understanding of this segment of human history. Using a multi-disciplinary approach incorporating paleoecological and organic geochemical analyses of a lacustrine sediment record, and climate modelling methodologies, we present evidence of prolonged human-caused environmental disturbance in modern-day northern Alaska and show that humans were present in this area as early as 32,000 years ago. We measured fecal biomarkers preserved in the Lake E5 sediment archive to confirm prolonged human presence in the watershed, and find evidence of contemporaneous burning, as inferred from macroscopic charcoal and polycyclic aromatic hydrocarbons. Climate simulations show that natural lightning ignitions were suppressed during the period of greatest fire frequency, and so we infer that humans likely played an important role in fire ignitions. We thus present new physical evidence of sustained human presence in eastern Beringia throughout the last Glacial, which reorients our understanding of the human migration to the Americas. Furthermore, our research offers new insight into the ecology of the mammoth steppe and the role of humans in the extinction of the Pleistocene megafauna.

Ignitability test method and apparatus

NASA Technical Reports Server (NTRS)

Bement, Laurence J. (Inventor); Bailey, James W. (Inventor); Schimmel, Morry L. (Inventor)

1991-01-01

An apparatus for testing ignitability of an initiator includes a body having a central cavity, an initiator holder for holding the initiator over the central cavity of the body, an ignition material holder disposed in the central cavity of the body and having a cavity facing the initiator holder which receives a measured quantity of ignition material to be ignited by the initiator. It contains a chamber in communication with the cavity of the ignition material and the central cavity of the body, and a measuring system for analyzing pressure characteristics generated by ignition of the ignition material by the initiator. The measuring system includes at least one transducer coupled with an oscillograph for recording pressure traces generated by ignition.

An Exploratory Investigation of the Influence of Igniter Chemistry on Ignition in Porous Bed Gun Propellants

DTIC Science & Technology

1981-09-01

nitrocellulose igniter materials using the Ignition Energetics Characterization Device (IECD). The results presented herein represent Phase II eperimental ...auxiliary test cham- bcz is a combustion gas diagnostic section designed to permit determination of the composition and enthalpy level of the gases...removal/assembly and propellant loading. 2.2 Igniter Characteristics 2.2.1 Baseline Igniter The igniter system, Figure 2.3, is designed to provide overall

Simultaneous dual mode combustion engine operating on spark ignition and homogenous charge compression ignition

DOEpatents

Fiveland, Scott B.; Wiggers, Timothy E.

2004-06-22

An engine particularly suited to single speed operation environments, such as stationary power generators. The engine includes a plurality of combustion cylinders operable under homogenous charge compression ignition, and at least one combustion cylinder operable on spark ignition concepts. The cylinder operable on spark ignition concepts can be convertible to operate under homogenous charge compression ignition. The engine is started using the cylinders operable under spark ignition concepts.

Manufacturing of Igniters for NHB 8060.1 Testing

NASA Technical Reports Server (NTRS)

Williams, James

1996-01-01

The purpose of this WJI is to incorporate a standard procedure to prepare, certify, and ship standard NHB 8060.1B and NHB 8060.1C igniters for flammability testing and to update LJI-320-35-18. The operations are divided into five parts as follows: A. Preparing the igniter mix; B. Extruding the igniters; C. Curing, cutting, and weighing the igniters; D. Certifying the igniters and E. Packaging, storing, and shipping the igniters

Salmonella interactions with plants and their associated microbiota

USDA-ARS?s Scientific Manuscript database

The increase in the incidence of gastroenteritis outbreaks linked to the consumption of foods of plant origin has ignited public concern and scientific interest in understanding interactions of human enteric pathogens with plants. Enteric disease caused by non-typhoidal Salmonella is a major public ...

30 CFR 7.502 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... the combined effects of air movement, heat, and humidity on the human body. Breathable oxygen. Oxygen.... Noncombustible material. Material, such as concrete or steel, that will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat. Overpressure. The highest pressure over the...

30 CFR 7.502 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the combined effects of air movement, heat, and humidity on the human body. Breathable oxygen. Oxygen.... Noncombustible material. Material, such as concrete or steel, that will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat. Overpressure. The highest pressure over the...

30 CFR 7.502 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... the combined effects of air movement, heat, and humidity on the human body. Breathable oxygen. Oxygen.... Noncombustible material. Material, such as concrete or steel, that will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat. Overpressure. The highest pressure over the...

30 CFR 7.502 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the combined effects of air movement, heat, and humidity on the human body. Breathable oxygen. Oxygen.... Noncombustible material. Material, such as concrete or steel, that will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat. Overpressure. The highest pressure over the...

30 CFR 7.502 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the combined effects of air movement, heat, and humidity on the human body. Breathable oxygen. Oxygen.... Noncombustible material. Material, such as concrete or steel, that will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat. Overpressure. The highest pressure over the...

A sustained-arc ignition system for internal combustion engines

NASA Technical Reports Server (NTRS)

Birchenough, A. G.

1977-01-01

A sustained-arc ignition system was developed for internal combustion engines. It produces a very-long-duration ignition pulse with an energy in the order of 100 millijoules. The ignition pulse waveform can be controlled to predetermined actual ignition requirements. The design of the sustained-arc ignition system is presented in the report.

Ignition of a human body by a modest external source: a case report.

PubMed

Palmiere, Cristian; Staub, Christian; La Harpe, Romano; Mangin, Patrice

2009-07-01

A case of sustained combustion of a human body that occurred in 2006 in Geneva, Switzerland, is presented. The body of a man was discovered at home and found to have been almost completely incinerated between the knees and the mid-chest, with less damage to the head, arms, lower legs and feet. His dog was also found dead just behind the house door. The external source of ignition was most likely a cigarette or a cigar. The chair in which the man had been sitting was largely consumed while other objects in the room exhibited only a brown oily or greasy coating and were virtually undamaged. Toxicological analyses carried out on the blood from the lower legs showed low levels of desalkylflurazepam. Alcohol concentration was 1.10 per thousand, carboxyhaemoglobin levels were 12% and cyanide concentration was 0.05 mg/L. Toxicological analyses carried out on the dog's blood showed carboxyhaemoglobin levels at 65%.

Human versus lightning ignition of presettlement surface fires in costal pine forests of the upper Great Lakes

USGS Publications Warehouse

Loope, Walter L.; Anderton, John B.

1998-01-01

To recover direct evidence of surface fires before European settlement, we sectioned fire-scarred logging-era stumps and trees in 39 small, physically isolated sand patches along the Great Lakes coast of northern Michigan and northern Wisconsin. While much information was lost to postharvest fire and stump deterioration, 147 fire-free intervals revealed in cross-sections from 29 coastal sand patches document numerous close interval surface fires before 1910; only one post-1910 fire was documented. Cross-sections from the 10 sections with records spanning >150 yr suggest local fire occurrence rates before 1910 ca. 10 times the present rate of lightning-caused fire. Since fire spread between or into coastal sand patches is rare, and seasonal use of the patches by Native people before 1910 is well documented, both historically and ethnographically, ignition by humans probably accounts for more than half of the pre-1910 fires recorded in cross-sections.

Aerospace Laser Ignition/Ablation Variable High Precision Thruster

NASA Technical Reports Server (NTRS)

Campbell, Jonathan W. (Inventor); Edwards, David L. (Inventor); Campbell, Jason J. (Inventor)

2015-01-01

A laser ignition/ablation propulsion system that captures the advantages of both liquid and solid propulsion. A reel system is used to move a propellant tape containing a plurality of propellant material targets through an ignition chamber. When a propellant target is in the ignition chamber, a laser beam from a laser positioned above the ignition chamber strikes the propellant target, igniting the propellant material and resulting in a thrust impulse. The propellant tape is advanced, carrying another propellant target into the ignition chamber. The propellant tape and ignition chamber are designed to ensure that each ignition event is isolated from the remaining propellant targets. Thrust and specific impulse may by precisely controlled by varying the synchronized propellant tape/laser speed. The laser ignition/ablation propulsion system may be scaled for use in small and large applications.

Precision shock tuning on the national ignition facility.

PubMed

Robey, H F; Celliers, P M; Kline, J L; Mackinnon, A J; Boehly, T R; Landen, O L; Eggert, J H; Hicks, D; Le Pape, S; Farley, D R; Bowers, M W; Krauter, K G; Munro, D H; Jones, O S; Milovich, J L; Clark, D; Spears, B K; Town, R P J; Haan, S W; Dixit, S; Schneider, M B; Dewald, E L; Widmann, K; Moody, J D; Döppner, T D; Radousky, H B; Nikroo, A; Kroll, J J; Hamza, A V; Horner, J B; Bhandarkar, S D; Dzenitis, E; Alger, E; Giraldez, E; Castro, C; Moreno, K; Haynam, C; LaFortune, K N; Widmayer, C; Shaw, M; Jancaitis, K; Parham, T; Holunga, D M; Walters, C F; Haid, B; Malsbury, T; Trummer, D; Coffee, K R; Burr, B; Berzins, L V; Choate, C; Brereton, S J; Azevedo, S; Chandrasekaran, H; Glenzer, S; Caggiano, J A; Knauer, J P; Frenje, J A; Casey, D T; Johnson, M Gatu; Séguin, F H; Young, B K; Edwards, M J; Van Wonterghem, B M; Kilkenny, J; MacGowan, B J; Atherton, J; Lindl, J D; Meyerhofer, D D; Moses, E

2012-05-25

Ignition implosions on the National Ignition Facility [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)] are underway with the goal of compressing deuterium-tritium fuel to a sufficiently high areal density (ρR) to sustain a self-propagating burn wave required for fusion power gain greater than unity. These implosions are driven with a very carefully tailored sequence of four shock waves that must be timed to very high precision to keep the fuel entropy and adiabat low and ρR high. The first series of precision tuning experiments on the National Ignition Facility, which use optical diagnostics to directly measure the strength and timing of all four shocks inside a hohlraum-driven, cryogenic liquid-deuterium-filled capsule interior have now been performed. The results of these experiments are presented demonstrating a significant decrease in adiabat over previously untuned implosions. The impact of the improved shock timing is confirmed in related deuterium-tritium layered capsule implosions, which show the highest fuel compression (ρR~1.0 g/cm(2)) measured to date, exceeding the previous record [V. Goncharov et al., Phys. Rev. Lett. 104, 165001 (2010)] by more than a factor of 3. The experiments also clearly reveal an issue with the 4th shock velocity, which is observed to be 20% slower than predictions from numerical simulation.

The ignitability of petrol vapours and potential for vapour phase explosion by use of TASER® law enforcement electronic control device.

PubMed

Clarke, C; Andrews, S P

2014-12-01

An experimental study was made of the potential of the TASER-X26™ law enforcement electronic control device to ignite petrol vapours if used by an officer to incapacitate a person soaked in petrol, or within a flammable atmosphere containing petrol vapour. Bench scale tests have shown that a wooden mannequin with pig skin covering the chest was a suitable representation of a human target. Full scale tests using the mannequin have shown that the arc from a TASER-X26™ is capable of igniting petrol/air vapours on a petrol-soaked person. Further tests in a 1/5 scale and a full scale compartment have shown that if a TASER is used within a compartment, a petrol vapour explosion (deflagration) may be achieved. It is evident from this research that if used in a flammable vapour rich environment, the device could prove fatal not only to the target but the TASER® operator as well. Copyright © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

Ignition conditions relaxation for central hot-spot ignition with an ion-electron non-equilibrium model

NASA Astrophysics Data System (ADS)

Fan, Zhengfeng; Liu, Jie

2016-10-01

We present an ion-electron non-equilibrium model, in which the hot-spot ion temperature is higher than its electron temperature so that the hot-spot nuclear reactions are enhanced while energy leaks are considerably reduced. Theoretical analysis shows that the ignition region would be significantly enlarged in the hot-spot rhoR-T space as compared with the commonly used equilibrium model. Simulations show that shocks could be utilized to create and maintain non-equilibrium conditions within the hot spot, and the hot-spot rhoR requirement is remarkably reduced for achieving self-heating. In NIF high-foot implosions, it is observed that the x-ray enhancement factors are less than unity, which is not self-consistent and is caused by assuming Te =Ti. And from this non-consistency, we could infer that ion-electron non-equilibrium exists in the high-foot implosions and the ion temperature could be 9% larger than the equilibrium temperature.

Knock detection system to improve petrol engine performance, using microphone sensor

NASA Astrophysics Data System (ADS)

Sujono, Agus; Santoso, Budi; Juwana, Wibawa Endra

2017-01-01

An increase of power and efficiency of spark ignition engines (petrol engines) are always faced with the problem of knock. Even the characteristics of the engine itself are always determined from the occurrence of knock. Until today, this knocking problem has not been solved completely. Knock is caused by principal factors that are influenced by the engine rotation, the load or opening the throttle and spark advance (ignition timing). In this research, the engine is mounted on the engine test bed (ETB) which is equipped with the necessary sensors. Knock detection using a new method, which is based on pattern recognition, which through the knock sound detection by using a microphone sensor, active filter, the regression of the normalized envelope function, and the calculation of the Euclidean distance is used for identifying knock. This system is implemented with a microcontroller which uses fuzzy logic controller ignition (FLIC), which aims to set proper spark advance, in accordance with operating conditions. This system can improve the engine performance for approximately 15%.

Composite, all-ceramics, high-peak power Nd:YAG/Cr(4+):YAG monolithic micro-laser with multiple-beam output for engine ignition.

PubMed

Pavel, Nicolaie; Tsunekane, Masaki; Taira, Takunori

2011-05-09

A passively Q-switched Nd:YAG/Cr(4+):YAG micro-laser with three-beam output was realized. A single active laser source made of a composite, all-ceramics Nd:YAG/Cr(4+):YAG monolithic cavity was pumped by three independent lines. At 5 Hz repetition rate, each line delivered laser pulses with ~2.4 mJ energy and 2.8-MW peak power. The M(2) factor of a laser beam was 3.7, and stable air breakdowns were realized. The increase of pump repetition rate up to 100 Hz improved the laser pulse energy by 6% and required ~6% increase of the pump pulse energy. Pulse timing of the laser-array beams can by adjusted by less than 5% tuning of an individual line pump energy, and therefore simultaneous multi-point ignition is possible. This kind of laser can be used for multi-point ignition of an automobile engine. © 2011 Optical Society of America

Automated analysis of hot spot X-ray images at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Khan, S. F.; Izumi, N.; Glenn, S.; Tommasini, R.; Benedetti, L. R.; Ma, T.; Pak, A.; Kyrala, G. A.; Springer, P.; Bradley, D. K.; Town, R. P. J.

2016-11-01

At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. For implosions with temperatures above ˜4 keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.

Automated analysis of hot spot X-ray images at the National Ignition Facility

DOE PAGES

Khan, S. F.; Izumi, N.; Glenn, S.; ...

2016-09-02

At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. Here, for implosions with temperatures above ~4keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.

Automated analysis of hot spot X-ray images at the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, S. F., E-mail: khan9@llnl.gov; Izumi, N.; Glenn, S.

At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. For implosions with temperatures above ∼4 keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.

Automated analysis of hot spot X-ray images at the National Ignition Facility.

PubMed

Khan, S F; Izumi, N; Glenn, S; Tommasini, R; Benedetti, L R; Ma, T; Pak, A; Kyrala, G A; Springer, P; Bradley, D K; Town, R P J

2016-11-01

At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. For implosions with temperatures above ∼4 keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.

Combustion-wave ignition for rocket engines

NASA Technical Reports Server (NTRS)

Liou, Larry C.

1992-01-01

The combustion wave ignition concept was experimentally studied in order to verify its suitability for application in baffled sections of a large booster engine combustion chamber. Gaseous oxygen/gaseous methane (GOX/GH4) and gaseous oxygen/gaseous hydrogen (GOX/GH2) propellant combinations were evaluated in a subscale combustion wave ignition system. The system included four element tubes capable of carrying ignition energy simultaneously to four locations, simulating four baffled sections. Also, direct ignition of a simulated Main Combustion Chamber (MCC) was performed. Tests were conducted over a range of mixture ratios and tube geometries. Ignition was consistently attained over a wide range of mixture ratios. And at every ignition, the flame propagated through all four element tubes. For GOX/GH4, the ignition system ignited the MCC flow at mixture ratios from 2 to 10 and for GOX/GH2 the ratios is from 2 to 13. The ignition timing was found to be rapid and uniform. The total ignition delay when using the MCC was under 11 ms, with the tube-to-tube, as well as the run-to-run, variation under 1 ms. Tube geometries were found to have negligible effect on the ignition outcome and timing.

Ignition of Hydrogen-Oxygen Rocket Combustor with Chlorine Trifluoride and Triethylaluminum

NASA Technical Reports Server (NTRS)

Gregory, John W.; Straight, David M.

1961-01-01

Ignition of a nominal-125-pound-thrust cold (2000 R) gaseous-hydrogen - liquid-oxygen rocket combustor with chlorine trifluoride (hypergolic with hydrogen) and triethylaluminum (hypergolic with oxygen) resulted in consistently smooth starting transients for a wide range of combustor operating conditions. The combustor exhaust nozzle discharged into air at ambient conditions. Each starting transient consisted of the following sequence of events: injection of the lead main propellant, injection of the igniter chemical, ignition of these two chemicals, injection of the second main propellant, ignition of the two main propellants, increase in chamber pressure to its terminal value, and cutoff of igniter-chemical flow. Smooth ignition was obtained with an ignition delay of less than 100 milliseconds for the reaction of the lead propellant with the igniter chemical using approximately 0.5 cubic inch (0-038 lb) of chlorine trifluoride or 1.0 cubic inch (0-031 lb) of triethylaluminum. These quantities of igniter chemical were sufficient to ignite a 20-percent-fuel hydrogen-oxygen mixture with a delay time of less than 15 milliseconds. Test results indicated that a simple, light weight chemical ignition system for hydrogen-oxygen rocket engines may be possible.

Optimal timing of wildfire prevention education

Treesearch

D. T. Butry; J. P. Prestemon; K. L. Abt

2010-01-01

Public outreach and wildfire education activities have been shown to limit the number of unintentional human-caused ignitions (i.e., 'accidental' wildfires). Such activities include the airing of public service announcements, visiting with homeowners in at-risk areas, distributing informative brochures and flyers, hosting of public forums (with presentations...

Hyperbaric and hypobaric chamber fires: a 73-year analysis.

PubMed

Sheffield, P J; Desautels, D A

1997-09-01

Fire can be catastrophic in the confined space of a hyperbaric chamber. From 1923 to 1996, 77 human fatalities occurred in 35 hyperbaric chamber fires, three human fatalities in a pressurized Apollo Command Module, and two human fatalities in three hypobaric chamber fires reported in Asia, Europe, and North America. Two fires occurred in diving bells, eight occurred in recompression (or decompression) chambers, and 25 occurred in clinical hyperbaric chambers. No fire fatalities were reported in the clinical hyperbaric chambers of North America. Chamber fires before 1980 were principally caused by electrical ignition. Since 1980, chamber fires have been primarily caused by prohibited sources of ignition that an occupant carried inside the chamber. Each fatal chamber fire has occurred in an enriched oxygen atmosphere (> 28% oxygen) and in the presence of abundant burnable material. Chambers pressurized with air (< 23.5% oxygen) had the only survivors. Information in this report was obtained from the literature and from the Undersea and Hyperbaric Medical Society's Chamber Experience and Mishap Database. This epidemiologic review focuses on information learned from critical analyses of chamber fires and how it can be applied to safe operation of hypobaric and hyperbaric chambers.

Ignitability test method

NASA Technical Reports Server (NTRS)

Bement, Laurence J.; Schimmel, Morry L.

1989-01-01

To overcome serious weaknesses in determining the performance of initiating devices, a novel 'ignitability test method', representing actual design interfaces and ignition materials, has been developed. Ignition device output consists of heat, light, gas an burning particles. Past research methods have evaluated these parameters individually. This paper describes the development and demonstration of an ignitability test method combining all these parameters, and the quantitative assessment of the ignition performance of two widely used percussion primers, the M42C1-PA101 and the M42C2-793. The ignition materials used for this evaluation were several powder, granule and pellet sizes of black powder and boron-potassium nitrate. This test method should be useful for performance evaluation of all initiator types, quality assurance, evaluation of ignition interfaces, and service life studies of initiators and ignition materials.

76 FR 20501 - Airworthiness Directives; Fokker Services B.V. Model F.27 Mark 050 Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-13

... regulations revealed that, if chafing occurs between the Fuel Quantity Probe (FQP) and the probe wiring, with..., if chafing occurs between the Fuel Quantity Probe (FQP) and the probe wiring, with additional factors... Quantity Probe (FQP) and the probe wiring, with additional factors, this may result in an ignition source...

Experimental investigation on the impacts of ignition energy and position on ignition processes in supersonic flows by laser induced plasma

NASA Astrophysics Data System (ADS)

An, Bin; Wang, Zhenguo; Yang, Leichao; Li, Xipeng; Zhu, Jiajian

2017-08-01

Cavity ignition of a model scramjet combustor fueled by ethylene was achieved through laser induced plasma, with inflow conditions of Ma = 2.92, total temperature T0 = 1650 K and stagnation pressure P0 = 2.6 MPa. The overall equivalent ratio was kept at 0.152 for all the tests. The ignition processes at different ignition energies and various ignition positions were captured by CH∗ and OH∗ chemiluminescence imaging. The results reveal that the initial flame kernel is carried to the cavity leading edge by the recirculation flow, and resides there for ∼100 μs before spreading downstream. The ignition time can be reduced, and the possibility of successful ignition for single laser pulse can be promoted by enhancing ignition energy. The scale and strength of the initial flame kernel is influenced by both the ignition energy and position. In present study, the middle part of the cavity is the best position for ignition, as it keeps a good balance between the strength of initial flame kernel and the impacts of strain rate in recirculation flow.

Contactless electric igniter for vehicle to lower exhaust emission and fuel consumption.

PubMed

Shen, Chih-Lung; Su, Jye-Chau

2014-01-01

An electric igniter for engine/hybrid vehicles is presented. The igniter comprises a flyback converter, a voltage-stacked capacitor, a PIC-based controller, a differential voltage detector, and an ignition coil, of which structure is non-contact type. Since the electric igniter adopts a capacitor to accumulate energy for engine ignition instead of traditional contacttype approach, it enhances the igniting performance of a spark plug effectively. As a result, combustion efficiency is promoted, fuel consumption is saved, and exhaust emission is reduced. The igniter not only is good for fuel efficiency but also can reduce HC and CO emission significantly, which therefore is an environmentally friendly product. The control core of the igniter is implemented on a single chip, which lowers discrete component count, reduces system volume, and increases reliability. In addition, the ignition timing can be programmed so that a timing regulator can be removed from the proposed system, simplifying its structure. To verify the feasibility and functionality of the igniter, key waveforms are measured and real-car experiments are performed as well.

Ignition of expandable polystyrene foam by a hot particle: an experimental and numerical study.

PubMed

Wang, Supan; Chen, Haixiang; Liu, Naian

2015-01-01

Many serious fires have occurred in recent years due to the ignition of external building insulation materials by hot metallic particles. This work studied the ignition of expandable polystyrene foam by hot metallic particles experimentally and numerically. In each experiment, a spherical steel particle was heated to a high temperature (within 1173-1373K) and then dropped to the surface of an expandable polystyrene foam block. The particles used in experiments ranged from 3mm to 7 mm in radius. The observed results for ignition were categorized into two types: "flaming ignition" and "no ignition", and the flaming ignition limit was determined by statistical analysis. According to the experimental observations, a numerical model was proposed, taking into account the reactant consumption and volatiles convection of expandable polystyrene decomposition in air. Three regimes, no ignition, unstable ignition and stable ignition, were identified, and two critical particle temperatures for separating the three regimes were determined. Comparison with the experimental data shows that the model can predict the range of critical ignition temperatures reasonably well. Copyright © 2014 Elsevier B.V. All rights reserved.

Contactless Electric Igniter for Vehicle to Lower Exhaust Emission and Fuel Consumption

PubMed Central

Su, Jye-Chau

2014-01-01

An electric igniter for engine/hybrid vehicles is presented. The igniter comprises a flyback converter, a voltage-stacked capacitor, a PIC-based controller, a differential voltage detector, and an ignition coil, of which structure is non-contact type. Since the electric igniter adopts a capacitor to accumulate energy for engine ignition instead of traditional contacttype approach, it enhances the igniting performance of a spark plug effectively. As a result, combustion efficiency is promoted, fuel consumption is saved, and exhaust emission is reduced. The igniter not only is good for fuel efficiency but also can reduce HC and CO emission significantly, which therefore is an environmentally friendly product. The control core of the igniter is implemented on a single chip, which lowers discrete component count, reduces system volume, and increases reliability. In addition, the ignition timing can be programmed so that a timing regulator can be removed from the proposed system, simplifying its structure. To verify the feasibility and functionality of the igniter, key waveforms are measured and real-car experiments are performed as well. PMID:24672372

Experimental and Numerical Study on Effect of Sample Orientation on Auto-Ignition and Piloted Ignition of Poly(methyl methacrylate)

PubMed Central

Peng, Fei; Zhou, Xiao-Dong; Zhao, Kun; Wu, Zhi-Bo; Yang, Li-Zhong

2015-01-01

In this work, the effect of seven different sample orientations from 0° to 90° on pilot and non-pilot ignition of PMMA (poly(methyl methacrylate)) exposed to radiation has been studied with experimental and numerical methods. Some new and significant conclusions are drawn from the study, including a U-shape curve of ignition time and critical mass flux as sample angle increases for pilot ignition conditions. However, in auto-ignition, the ignition time and critical mass flux increases with sample angle α. Furthermore, a computational fluid dynamic model have been built based on the Fire Dynamics Simulator (FDS6) code to investigate the mechanisms controlling the dependence on sample orientation of the ignition of PMMA under external radiant heating. The results of theoretical analysis and modeling results indicate the decrease of total incident heat flux at sample surface plays the dominant role during the ignition processes of auto-ignition, but the volatiles gas flow has greater influence for piloted ignition conditions. PMID:28793421

Additively Manufactured Metals in Oxygen Systems Project

NASA Technical Reports Server (NTRS)

Tylka, Jonathan

2015-01-01

Metals produced by additive manufacturing methods, such as Powder Bed Fusion Technology, are now mature enough to be considered for qualification in human spaceflight oxygen systems. The mechanical properties of metals produced through AM processes are being systematically studied. However, it is unknown whether AM metals in oxygen applications may present an increased risk of flammability or ignition as compared to wrought metals of the same metallurgical composition due to increased porosity. Per NASA-STD-6001B materials to be used in oxygen system applications shall be based on flammability and combustion test data, followed by a flammability assessment. Without systematic flammability and ignition testing in oxygen there is no credible method for NASA to accurately evaluate the risk of using AM metals in oxygen systems.

Ignitability test method and apparatus

NASA Technical Reports Server (NTRS)

Bement, Laurence J. (Inventor); Bailey, James W. (Inventor); Schimmel, Morry L. (Inventor)

1989-01-01

An apparatus for testing ignitability of an initiator includes a body with a central cavity, initiator holder for holding the initiator over the central cavity of the body, an ignition material holder disposed in the central cavity of the body and a cavity facing the initiator holder which receives a measured quantity of ignition material to be ignited by the initiator and a chamber in communication with the cavity of the ignition material holder and the central cavity of the body. A measuring system for analyzing pressure characteristics is generated by ignition material by the initiator. The measuring system includes at least one transducer coupled to an oscillograph for recording pressure traces generated by ignition.

Analytical and experimental study of resonance ignition tubes

NASA Technical Reports Server (NTRS)

Stabinsky, L.

1973-01-01

The application of the gas-dynamic resonance concept was investigated in relation to ignition of rocket propulsion systems. Analytical studies were conducted to delineate the potential uses of resonance ignition in oxygen/hydrogen bipropellant and hydrazine monopropellant rocket engines. Experimental studies were made to: (1) optimize the resonance igniter configuration, and (2) evaluate the ignition characteristics when operating with low temperature oxygen and hydrogen at the inlet to the igniter.

A Comparative Study of Cycle Variability of Laser Plug Ignition vs Classical Spark Plug Ignition in Combustion Engines

NASA Astrophysics Data System (ADS)

Done, Bogdan

2017-10-01

Over the past 30 years numerous studies and laboratory experiments have researched the use of laser energy to ignite gas and fuel-air mixtures. The actual implementation of this laser application has still to be fully achieved in a commercial automotive application. Laser Plug Ignition as a replacement for Spark Plug Ignition in the internal combustion engines of automotive vehicles, offers several potential benefits such as extending lean burn capability, reducing the cyclic variability between combustion cycles and decreasing the total amount of ignition costs, and implicitly weight and energy requirements. The paper presents preliminary results of cycle variability study carried on a SI Engine equipped with laser Plug Ignition system. Versus classic ignition system, the use of the laser Plug Ignition system assures the reduction of the combustion process variability, reflected in the lower values of the coefficient of variability evaluated for indicated mean effective pressure, maximum pressure, maximum pressure angle and maximum pressure rise rate. The laser plug ignition system was mounted on an experimental spark ignition engine and tested at the regime of 90% load and 2800 rev/min, at dosage of λ=1.1. Compared to conventional spark plug, laser ignition assures the efficiency at lean dosage.

Effect of flow velocity and temperature on ignition characteristics in laser ignition of natural gas and air mixtures

NASA Astrophysics Data System (ADS)

Griffiths, J.; Riley, M. J. W.; Borman, A.; Dowding, C.; Kirk, A.; Bickerton, R.

2015-03-01

Laser induced spark ignition offers the potential for greater reliability and consistency in ignition of lean air/fuel mixtures. This increased reliability is essential for the application of gas turbines as primary or secondary reserve energy sources in smart grid systems, enabling the integration of renewable energy sources whose output is prone to fluctuation over time. This work details a study into the effect of flow velocity and temperature on minimum ignition energies in laser-induced spark ignition in an atmospheric combustion test rig, representative of a sub 15 MW industrial gas turbine (Siemens Industrial Turbomachinery Ltd., Lincoln, UK). Determination of minimum ignition energies required for a range of temperatures and flow velocities is essential for establishing an operating window in which laser-induced spark ignition can operate under realistic, engine-like start conditions. Ignition of a natural gas and air mixture at atmospheric pressure was conducted using a laser ignition system utilizing a Q-switched Nd:YAG laser source operating at 532 nm wavelength and 4 ns pulse length. Analysis of the influence of flow velocity and temperature on ignition characteristics is presented in terms of required photon flux density, a useful parameter to consider during the development laser ignition systems.

Ignition of Cellulosic Paper at Low Radiant Fluxes

NASA Technical Reports Server (NTRS)

White, K. Alan

1996-01-01

The ignition of cellulosic paper by low level thermal radiation is investigated. Past work on radiative ignition of paper is briefly reviewed. No experimental study has been reported for radiative ignition of paper at irradiances below 10 Watts/sq.cm. An experimental study of radiative ignition of paper at these low irradiances is reported. Experimental parameters investigated and discussed include radiant power levels incident on the sample, the method of applying the radiation (focussed vs. diffuse Gaussian source), the presence and relative position of a separate pilot ignition source, and the effects of natural convection (buoyancy) on the ignition process in a normal gravity environment. It is observed that the incident radiative flux (in W/sq.cm) has the greatest influence on ignition time. For a given flux level, a focussed Gaussian source is found to be advantageous to a more diffuse, lower amplitude, thermal source. The precise positioning of a pilot igniter relative to gravity and to the fuel sample affects the ignition process, but the precise effects are not fully understood. Ignition was more readily achieved and sustained with a horizontal fuel sample, indicating the buoyancy plays a role in the ignition process of cellulosic paper. Smoldering combustion of doped paper samples was briefly investigated, and results are discussed.

The Civil Rights Movement: A Humanities Rainbow

ERIC Educational Resources Information Center

Wheat, Brenda M.; Kapavik, Robin Robinson

2004-01-01

During recent renovation work at the Collin County Courthouse in a suburb of Dallas Texas, workers discovered "for colored" and "for white" signs underneath layers of plaster above the bathroom doors. The discovery has ignited controversy between citizens who are concerned with the eventual fate of the signs. Some residents of…

Impacts of a human disturbance on greater prairie chickens: Insights from a spatial IBM

EPA Science Inventory

The Flint Hills of Kansas are home to the largest remaining tallgrass prairie ecosystem in North America. The Flint Hills are currently managed under an early season burn-intensive stocking regime, whereby ranchers will ignite the majority of pasture land each year to increase r...

75 FR 47520 - Standards of Performance for Stationary Compression Ignition and Spark Ignition Internal...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-06

... Ignition Internal Combustion Engines AGENCY: Environmental Protection Agency (EPA). ACTION: Extension of... for stationary compression ignition and spark ignition internal combustion engines. In this [[Page... combustion engines. After publication of the proposed rule, EPA received requests from the American Petroleum...

Dual-Laser-Pulse Ignition

NASA Technical Reports Server (NTRS)

Trinh, Huu; Early, James W.; Thomas, Matthew E.; Bossard, John A.

2006-01-01

A dual-pulse laser (DPL) technique has been demonstrated for generating laser-induced sparks (LIS) to ignite fuels. The technique was originally intended to be applied to the ignition of rocket propellants, but may also be applicable to ignition in terrestrial settings in which electric igniters may not be suitable.

Human impacts on 20th century fire dynamics and implications for global carbon and water trajectories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Fang; Lawrence, David M.; Bond-Lamberty, Ben

Fire is a fundamental Earth system process and the primary ecosystem disturbance on the global scale. It affects carbon and water cycles through changing terrestrial ecosystems, and at the same time, is regulated by weather and climate, vegetation characteristics, and, importantly, human ignitions and suppression (i.e., the direct human effect on fire). Here, we utilize the Community Land Model version 4.5 (CLM4.5) to quantify the impacts of changes in human ignition and suppression on fire dynamics and associated carbon and water cycles. We find that the impact is to significantly reduce the 20th century global burned area by a centurymore » average of 38 Mha/yr and by 103 Mha/yr at the end of the century. Land carbon gain is weakened by 17% over the 20th century, mainly due to increased human deforestation fires and associated escape fires (i.e., degradation fires) in the tropical humid forests, even though the decrease in burned area in many other regions due to human fire suppression acts to increase land carbon gain. The direct human effect on fire weakens the upward trend in global runoff throughout the century by 6% and enhances the upward trend in global evapotranspiration since ~ 1945 by 7%. In addition, the above impacts in densely populated, highly developed (if population density > 0.1 person/km2), or moderately populated and developed regions are of opposite sign to those in other regions. Our study suggests that particular attention should be paid to human deforestation and degradation fires in the tropical humid forests when reconstructing and projecting fire carbon emissions and net atmosphere-land carbon exchange and estimating resultant impacts of direct human effect on fire.« less

Human impacts on 20th century fire dynamics and implications for global carbon and water trajectories

NASA Astrophysics Data System (ADS)

Li, Fang; Lawrence, David M.; Bond-Lamberty, Ben

2018-03-01

Fire is a fundamental Earth system process and the primary ecosystem disturbance on the global scale. It affects carbon and water cycles through changing terrestrial ecosystems, and at the same time, is regulated by weather and climate, vegetation characteristics, and, importantly, human ignitions and suppression (i.e., the direct human effect on fire). Here, we utilize the Community Land Model version 4.5 (CLM4.5) to quantify the impacts of changes in human ignition and suppression on fire dynamics and associated carbon and water cycles. We find that the impact is to significantly reduce the 20th century global burned area by a century average of 38 Mha/yr and by 103 Mha/yr at the end of the century. Land carbon gain is weakened by 17% over the 20th century, mainly due to increased human deforestation fires and associated escape fires (i.e., degradation fires) in the tropical humid forests, even though the decrease in burned area in many other regions due to human fire suppression acts to increase land carbon gain. The direct human effect on fire weakens the upward trend in global runoff throughout the century by 6% and enhances the upward trend in global evapotranspiration since 1945 by 7%. In addition, the above impacts in densely populated, highly developed (if population density > 0.1 person/km2), or moderately populated and developed regions are of opposite sign to those in other regions. Our study suggests that particular attention should be paid to human deforestation and degradation fires in the tropical humid forests when reconstructing and projecting fire carbon emissions and net atmosphere-land carbon exchange and estimating resultant impacts of direct human effect on fire.

14 CFR 33.37 - Ignition system.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Ignition system. 33.37 Section 33.37... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.37 Ignition system. Each spark ignition engine must have a dual ignition system with at least two spark plugs for each...

40 CFR 264.17 - General requirements for ignitable, reactive, or incompatible wastes.

Code of Federal Regulations, 2011 CFR

2011-07-01

... accidental ignition or reaction of ignitable or reactive waste. This waste must be separated and protected from sources of ignition or reaction including but not limited to: open flames, smoking, cutting and... (e.g., from heat-producing chemical reactions), and radiant heat. While ignitable or reactive waste...

40 CFR 264.17 - General requirements for ignitable, reactive, or incompatible wastes.

Code of Federal Regulations, 2010 CFR

2010-07-01

... accidental ignition or reaction of ignitable or reactive waste. This waste must be separated and protected from sources of ignition or reaction including but not limited to: open flames, smoking, cutting and... (e.g., from heat-producing chemical reactions), and radiant heat. While ignitable or reactive waste...

40 CFR 264.17 - General requirements for ignitable, reactive, or incompatible wastes.

Code of Federal Regulations, 2014 CFR

2014-07-01

... (e.g., from heat-producing chemical reactions), and radiant heat. While ignitable or reactive waste... accidental ignition or reaction of ignitable or reactive waste. This waste must be separated and protected from sources of ignition or reaction including but not limited to: open flames, smoking, cutting and...

40 CFR 264.17 - General requirements for ignitable, reactive, or incompatible wastes.

Code of Federal Regulations, 2012 CFR

2012-07-01

... (e.g., from heat-producing chemical reactions), and radiant heat. While ignitable or reactive waste... accidental ignition or reaction of ignitable or reactive waste. This waste must be separated and protected from sources of ignition or reaction including but not limited to: open flames, smoking, cutting and...

Fundamental ignition study for material fire safety improvement, part 1

NASA Technical Reports Server (NTRS)

Paciorek, K. L.; Zung, L. B.

1970-01-01

The investigation of preignition, ignition, and combustion characteristics of Delrin (acetate terminated polyformaldehyde) and Teflon (polytetrafluoroethylene) resins in air and oxygen are presented. The determination of ignition limits and their dependence on temperature and the oxidizing media, as well as the analyses of the volatiles produced, were studied. Tests were conducted in argon, an inert medium in which only purely pyrolytic reactions can take place, using the stagnation burner arrangement designed and constructed for this purpose. A theoretical treatment of the ignition and combination phenomena was devised. In the case of Delrin the ignition and ignition delays are apparently independent of the gas (air, oxygen) temperatures. The results indicate that hydrogen is the ignition triggering agent. Teflon ignition limits were established in oxygen only.

Ignition characterization of the GOX/ethanol propellant combination

NASA Technical Reports Server (NTRS)

Lawver, B. R.; Rousar, D. C.; Boyd, W. C.

1984-01-01

This paper describes the results of a study to define the ignition characteristics and thruster pulse mode capabilities of the GOX/ethanol propellant combination. Ignition limits were defined in terms of mixture ratio and cold flow pressure using a spark initiated torch igniter. Igniter tests were run over a wide range of cold flow pressure, propellant temperature and mixture ratio. The product of cold flow pressure and igniter chamber diameter was used to correlate mixture ratio regimes of ignition and nonignition. Engine ignition reliability and pulse mode capability were demonstrated using a 620 lbF thruster with an integrated torch igniter. The nominal chamber pressure and mixture ratio were 150 psia and 1.8, respectively, thruster tests were run over a wide range of chamber pressures and mixture ratios. The feasibility of thruster pulse mode operation with the non-hypergolic GOX/ethanol propellant combination was demonstrated.

On thermonuclear ignition criterion at the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Baolian; Kwan, Thomas J. T.; Wang, Yi-Ming

2014-10-15

Sustained thermonuclear fusion at the National Ignition Facility remains elusive. Although recent experiments approached or exceeded the anticipated ignition thresholds, the nuclear performance of the laser-driven capsules was well below predictions in terms of energy and neutron production. Such discrepancies between expectations and reality motivate a reassessment of the physics of ignition. We have developed a predictive analytical model from fundamental physics principles. Based on the model, we obtained a general thermonuclear ignition criterion in terms of the areal density and temperature of the hot fuel. This newly derived ignition threshold and its alternative forms explicitly show the minimum requirementsmore » of the hot fuel pressure, mass, areal density, and burn fraction for achieving ignition. Comparison of our criterion with existing theories, simulations, and the experimental data shows that our ignition threshold is more stringent than those in the existing literature and that our results are consistent with the experiments.« less

Catalytic ignition of hydrogen/oxygen

NASA Technical Reports Server (NTRS)

Green, James M.; Zurawski, Robert L.

1988-01-01

An experimental program was conducted to evaluate the catalytic ignition of gaseous hydrogen and oxygen. Shell 405 granular catalyst and a unique monolithic sponge catalyst were tested. Mixture ratio, mass flow rate, propellant inlet temperature, and back pressure were varied parametrically in testing to determine the operational limits of a catalytic igniter. The test results showed that the gaseous hydrogen/oxygen propellant combination can be ignited catalytically using Shell 405 catalyst over a wide range of mixture ratios, mass flow rates, and propellant injection temperatures. These operating conditions must be optimized to ensure reliable ignition for an extended period of time. The results of the experimental program and the established operational limits for a catalytic igniter using both the granular and monolithic catalysts are presented. The capabilities of a facility constructed to conduct the igniter testing and the advantages of a catalytic igniter over other ignition systems for gaseous hydrogen and oxygen are also discussed.

Investigation of Al/CuO multilayered thermite ignition

NASA Astrophysics Data System (ADS)

Nicollet, Andréa; Lahiner, Guillaume; Belisario, Andres; Souleille, Sandrine; Djafari-Rouhani, Mehdi; Estève, Alain; Rossi, Carole

2017-01-01

The ignition of the Al/CuO multilayered material is studied experimentally to explore the effects of the heating surface area, layering, and film thickness on the ignition characteristics and reaction performances. After the description of the micro-initiator devices and ignition conditions, we show that the heating surface area must be properly calibrated to optimize the nanothermite ignition performances. We demonstrated experimentally that a heating surface area of 0.25 mm2 is sufficient to ignite a multilayered thermite film of 1.6 mm wide by a few cm long, with a success rate of 100%. A new analytical and phenomenological ignition model based on atomic diffusion across layers and thermal exchange is also proposed. This model considers that CuO first decomposes into Cu2O, and then the oxygen diffuses across the Cu2O and Al2O3 layers before reaching the Al layer, where it reacts to form Al2O3. The theoretical results in terms of ignition response times confirm the experimental observation. The increase of the heating surface area leads to an increase of the ignition response time and ignition power threshold (go/no go condition). We also provide evidence that, for any heating surface area, the ignition time rapidly decreases when the electrical power density increases until an asymptotic value. This time point is referred to as the minimum response ignition time, which is a characteristic of the multilayered thermite itself. At the stoichiometric ratio (Al thickness is half of the CuO thickness), the minimum ignition response time can be easily tuned from 59 μs to 418 ms by tuning the heating surface area. The minimum ignition response time increases when the bilayer thickness increases. This work not only provides a set of micro-initiator design rules to obtain the best ignition conditions and reaction performances but also details a reliable and robust MicroElectroMechanical Systems process to fabricate igniters and brings new understanding of phenomena governing the ignition process of Al/CuO multilayers.

Experimental Investigation of Augmented Spark Ignition of a LO2/LCH4 Reaction Control Engine at Altitude Conditions

NASA Technical Reports Server (NTRS)

Kleinhenz, Julie; Sarmiento, Charles; Marshall, William

2012-01-01

The use of nontoxic propellants in future exploration vehicles would enable safer, more cost-effective mission scenarios. One promising green alternative to existing hypergols is liquid methane (LCH4) with liquid oxygen (LO2). A 100 lbf LO2/LCH4 engine was developed under the NASA Propulsion and Cryogenic Advanced Development project and tested at the NASA Glenn Research Center Altitude Combustion Stand in a low pressure environment. High ignition energy is a perceived drawback of this propellant combination; so this ignition margin test program examined ignition performance versus delivered spark energy. Sensitivity of ignition to spark timing and repetition rate was also explored. Three different exciter units were used with the engine s augmented (torch) igniter. Captured waveforms indicated spark behavior in hot fire conditions was inconsistent compared to the well-behaved dry sparks. This suggests that rising pressure and flow rate increase spark impedance and may at some point compromise an exciter s ability to complete each spark. The reduced spark energies of such quenched deliveries resulted in more erratic ignitions, decreasing ignition probability. The timing of the sparks relative to the pressure/flow conditions also impacted the probability of ignition. Sparks occurring early in the flow could trigger ignition with energies as low as 1 to 6 mJ, though multiple, similarly timed sparks of 55 to 75 mJ were required for reliable ignition. Delayed spark application and reduced spark repetition rate both correlated with late and occasional failed ignitions. An optimum time interval for spark application and ignition therefore coincides with propellant introduction to the igniter.

Spark Ignition Characteristics of a L02/LCH4 Engine at Altitude Conditions

NASA Technical Reports Server (NTRS)

Kleinhenz, Julie; Sarmiento, Charles; Marshall, William

2012-01-01

The use of non-toxic propellants in future exploration vehicles would enable safer, more cost effective mission scenarios. One promising "green" alternative to existing hypergols is liquid methane/liquid oxygen. To demonstrate performance and prove feasibility of this propellant combination, a 100lbf LO2/LCH4 engine was developed and tested under the NASA Propulsion and Cryogenic Advanced Development (PCAD) project. Since high ignition energy is a perceived drawback of this propellant combination, a test program was performed to explore ignition performance and reliability versus delivered spark energy. The sensitivity of ignition to spark timing and repetition rate was also examined. Three different exciter units were used with the engine s augmented (torch) igniter. Propellant temperature was also varied within the liquid range. Captured waveforms indicated spark behavior in hot fire conditions was inconsistent compared to the well-behaved dry sparks (in quiescent, room air). The escalating pressure and flow environment increases spark impedance and may at some point compromise an exciter s ability to deliver a spark. Reduced spark energies of these sparks result in more erratic ignitions and adversely affect ignition probability. The timing of the sparks relative to the pressure/flow conditions also impacted the probability of ignition. Sparks occurring early in the flow could trigger ignition with energies as low as 1-6mJ, though multiple, similarly timed sparks of 55-75mJ were required for reliable ignition. An optimum time interval for spark application and ignition coincided with propellant introduction to the igniter and engine. Shifts of ignition timing were manifested by changes in the characteristics of the resulting ignition.

Spark Ignition Characteristics of a LO2/LCH4 Engine at Altitude Conditions

NASA Technical Reports Server (NTRS)

Kleinhenz, Julie; Sarmiento, Charles; Marshall, William

2012-01-01

The use of non-toxic propellants in future exploration vehicles would enable safer, more cost effective mission scenarios. One promising "green" alternative to existing hypergols is liquid methane/liquid oxygen. To demonstrate performance and prove feasibility of this propellant combination, a 100lbf LO2/LCH4 engine was developed and tested under the NASA Propulsion and Cryogenic Advanced Development (PCAD) project. Since high ignition energy is a perceived drawback of this propellant combination, a test program was performed to explore ignition performance and reliability versus delivered spark energy. The sensitivity of ignition to spark timing and repetition rate was also examined. Three different exciter units were used with the engine's augmented (torch) igniter. Propellant temperature was also varied within the liquid range. Captured waveforms indicated spark behavior in hot fire conditions was inconsistent compared to the well-behaved dry sparks (in quiescent, room air). The escalating pressure and flow environment increases spark impedance and may at some point compromise an exciter.s ability to deliver a spark. Reduced spark energies of these sparks result in more erratic ignitions and adversely affect ignition probability. The timing of the sparks relative to the pressure/flow conditions also impacted the probability of ignition. Sparks occurring early in the flow could trigger ignition with energies as low as 1-6mJ, though multiple, similarly timed sparks of 55-75mJ were required for reliable ignition. An optimum time interval for spark application and ignition coincided with propellant introduction to the igniter and engine. Shifts of ignition timing were manifested by changes in the characteristics of the resulting ignition.

Nano-Ignition Torch Applied to Cryogenic H2/O2 Coaxial Jet

DTIC Science & Technology

2016-01-04

developed and ignition of liquid fuel sprays by the torch has been achieved. In this report, we will describe the experimental procedure for producing...ignition that is induced by a compact Xe-flash, including the results for photoignition of a simple fuel spray in air as well as ignition of a coaxial...window. Experimental Setup for Fuel Spray Ignition Three different setups were utilized for the fuel ignition experiments. The first one was used

40 CFR 267.17 - What are the requirements for managing ignitable, reactive, or incompatible wastes?

Code of Federal Regulations, 2010 CFR

2010-07-01

... accidental ignition or reaction of ignitable or reactive waste by following these requirements: (1) You must separate these wastes and protect them from sources of ignition or reaction such as: open flames, smoking...), spontaneous ignition (for example, from heat-producing chemical reactions), and radiant heat. (2) While...

40 CFR 267.17 - What are the requirements for managing ignitable, reactive, or incompatible wastes?

Code of Federal Regulations, 2011 CFR

2011-07-01

... accidental ignition or reaction of ignitable or reactive waste by following these requirements: (1) You must separate these wastes and protect them from sources of ignition or reaction such as: open flames, smoking...), spontaneous ignition (for example, from heat-producing chemical reactions), and radiant heat. (2) While...

Combined target factor analysis and Bayesian soft-classification of interference-contaminated samples: forensic fire debris analysis.

PubMed

Williams, Mary R; Sigman, Michael E; Lewis, Jennifer; Pitan, Kelly McHugh

2012-10-10

A bayesian soft classification method combined with target factor analysis (TFA) is described and tested for the analysis of fire debris data. The method relies on analysis of the average mass spectrum across the chromatographic profile (i.e., the total ion spectrum, TIS) from multiple samples taken from a single fire scene. A library of TIS from reference ignitable liquids with assigned ASTM classification is used as the target factors in TFA. The class-conditional distributions of correlations between the target and predicted factors for each ASTM class are represented by kernel functions and analyzed by bayesian decision theory. The soft classification approach assists in assessing the probability that ignitable liquid residue from a specific ASTM E1618 class, is present in a set of samples from a single fire scene, even in the presence of unspecified background contributions from pyrolysis products. The method is demonstrated with sample data sets and then tested on laboratory-scale burn data and large-scale field test burns. The overall performance achieved in laboratory and field test of the method is approximately 80% correct classification of fire debris samples. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

A New Test Method for Material Flammability Assessment in Microgravity and Extraterrestrial Environments

NASA Technical Reports Server (NTRS)

Olson, S. L.; Beeson, H. D.; Haas, J. P.; Baas, J. S.

2004-01-01

The standard oxygen consumption (cone) calorimeter (described in ASTM E 1354 and NASA STD 6001 Test 2) is modified to provide a bench-scale test environment that simulates the low velocity buoyant or ventilation flow generated by or around a burning surface in a spacecraft or extraterrestrial gravity level. The Equivalent Low Stretch Apparatus (ELSA) uses an inverted cone geometry with the sample burning in a ceiling fire (stagnation flow) configuration. For a fixed radiant flux, ignition delay times for characterization material PMMA are shown to decrease by a factor of three at low stretch, demonstrating that ignition delay times determined from normal cone tests significantly underestimate the risk in microgravity. The critical heat flux for ignition is found to be lowered at low stretch as the convective cooling is reduced. At the limit of no stretch, any heat flux that exceeds the surface radiative loss at the surface ignition temperature is sufficient for ignition. Regression rates for PMMA increase with heat flux and stretch rate, but regression rates are much more sensitive to heat flux at the low stretch rates, where a modest increase in heat flux of 25 kW/m2 increases the burning rates by an order of magnitude. The global equivalence ratio of these flames is very fuel rich, and the quantity of CO produced in this configuration is significantly higher than standard cone tests. These results [2] demonstrate the ELSA apparatus allows us to conduct normal gravity experiments that accurately and quantifiably evaluate a material s flammability characteristics in the real-use environment of spacecraft or extra-terrestrial gravitational acceleration. These results also demonstrate that current NASA STD 6001 Test 2 (standard cone) is not conservative since it evaluates materials flammability with a much higher inherent buoyant convective flow.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perry, William L; Gunderson, Jake A; Dickson, Peter M

There has been a long history of interest in the decomposition kinetics of HMX and HMX-based formulations due to the widespread use of this explosive in high performance systems. The kinetics allow us to predict, or attempt to predict, the behavior of the explosive when subjected to thermal hazard scenarios that lead to ignition via impact, spark, friction or external heat. The latter, commonly referred to as 'cook off', has been widely studied and contemporary kinetic and transport models accurately predict time and location of ignition for simple geometries. However, there has been relatively little attention given to the problemmore » of localized ignition that results from the first three ignition sources of impact, spark and friction. The use of a zero-order single-rate expression describing the exothermic decomposition of explosives dates to the early work of Frank-Kamanetskii in the late 1930s and continued through the 60's and 70's. This expression provides very general qualitative insight, but cannot provide accurate spatial or timing details of slow cook off ignition. In the 70s, Catalano, et al., noted that single step kinetics would not accurately predict time to ignition in the one-dimensional time to explosion apparatus (ODTX). In the early 80s, Tarver and McGuire published their well-known three step kinetic expression that included an endothermic decomposition step. This scheme significantly improved the accuracy of ignition time prediction for the ODTX. However, the Tarver/McGuire model could not produce the internal temperature profiles observed in the small-scale radial experiments nor could it accurately predict the location of ignition. Those factors are suspected to significantly affect the post-ignition behavior and better models were needed. Brill, et al. noted that the enthalpy change due to the beta-delta crystal phase transition was similar to the assumed endothermic decomposition step in the Tarver/McGuire model. Henson, et al., deduced the kinetics and thermodynamics of the phase transition, providing Dickson, et al. with the information necessary to develop a four-step model that included a two-step nucleation and growth mechanism for the {beta}-{delta} phase transition. Initially, an irreversible scheme was proposed. That model accurately predicted the spatial and temporal cook off behavior of the small-scale radial experiment under slow heating conditions, but did not accurately capture the endothermic phase transition at a faster heating rate. The current version of the four-step model includes reversibility and accurately describes the small-scale radial experiment over a wide range of heating rates. We have observed impact-induced friction ignition of PBX 9501 with grit embedded between the explosive and the lower anvil surface. Observation was done using an infrared camera looking through the sapphire bottom anvil. Time to ignition and temperature-time behavior were recorded. The time to ignition was approximately 500 microseconds and the temperature was approximately 1000 K. The four step reversible kinetic scheme was previously validated for slow cook off scenarios. Our intention was to test the validity for significantly faster hot-spot processes, such as the impact-induced grit friction process studied here. We found the model predicted the ignition time within experimental error. There are caveats to consider when evaluating the agreement. The primary input to the model was friction work over an area computed by a stress analysis. The work rate itself, and the relative velocity of the grit and substrate both have a strong dependence on the initial position of the grit. Any errors in the analysis or the initial grit position would affect the model results. At this time, we do not know the sensitivity to these issues. However, the good agreement does suggest the four step kinetic scheme may have universal applicability for HMX systems.« less

Relation between inflammables and ignition sources in aircraft environments

NASA Technical Reports Server (NTRS)

Scull, Wilfred E

1951-01-01

A literature survey was conducted to determine the relation between aircraft ignition sources and inflammables. Available literature applicable to the problem of aircraft fire hazards is analyzed and discussed. Data pertaining to the effect of many variables on ignition temperatures, minimum ignition pressures, minimum spark-ignition energies of inflammables, quenching distances of electrode configurations, and size of openings through which flame will not propagate are presented and discussed. Ignition temperatures and limits of inflammability of gasoline in air in different test environments, and the minimum ignition pressures and minimum size of opening for flame propagation in gasoline-air mixtures are included; inerting of gasoline-air mixtures is discussed.

Pre-Ionization Controlled Laser Plasma Formation for Ignition Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shneider, Mikhail

The presented research explored new physics and ignition schemes based on laser induced plasmas that are fundamentally distinct from past laser ignition research focused on single laser pulses. Specifically, we consider the use of multiple laser pulses where the first pulse provides pre-ionization allowing controlled absorption of the second pulse. In this way, we can form tailored laser plasmas in terms of their ionization fraction, gas temperature (e.g. to achieve elevated temperature of ~2000 K ideally suited for an ignition source), reduced energy loss to shock waves and radiation, and large kernel size (e.g. length ~1-10 cm). The proposed researchmore » included both experimental and modeling efforts, at Colorado State University, Princeton University and University of Tennessee, towards the basic science of the new laser plasma approach with emphasis on tailoring the plasmas to practical propulsion systems. Experimental results (CSU) show that the UV beam produces a pre-ionized volume which assists in breakdown of the NIR beam, leading to reduction in NIR breakdown threshold by factor of >2. Numerical modeling is performed to examine the ionization and breakdown of both beams. The main theoretical and computational parts of the work were done at Princeton University. The modeled breakdown threshold of the NIR, including assist by pre-ionization, is in reasonable agreement with the experimental results.« less

Enhancing the Ignition, Hardness and Compressive Response of Magnesium by Reinforcing with Hollow Glass Microballoons

PubMed Central

Gupta, Manoj

2017-01-01

Magnesium (Mg)/glass microballoons (GMB) metal matrix syntactic foams (1.47–1.67 g/cc) were synthesized using a disintegrated melt deposition (DMD) processing route. Such syntactic foams are of great interest to the scientific community as potential candidate materials for the ever-changing demands in automotive, aerospace, and marine sectors. The synthesized composites were evaluated for their microstructural, thermal, and compressive properties. Results showed that microhardness and the dimensional stability of pure Mg increased with increasing GMB content. The ignition response of these foams was enhanced by ~22 °C with a 25 wt % GMB addition to the Mg matrix. The authors of this work propose a new parameter, ignition factor, to quantify the superior ignition performance that the developed Mg foams exhibit. The room temperature compressive strengths of pure Mg increased with the addition of GMB particles, with Mg-25 wt % GMB exhibiting the maximum compressive yield strength (CYS) of 161 MPa and an ultimate compressive strength (UCS) of 232 MPa for a GMB addition of 5 wt % in Mg. A maximum failure strain of 37.7% was realized in Mg-25 wt % GMB foam. The addition of GMB particles significantly enhanced the energy absorption by ~200% prior to compressive failure for highest filler loading, as compared to pure Mg. Finally, microstructural changes in Mg owing to the presence of hollow GMB particles were elaborately discussed. PMID:28841189

Enhancing the Ignition, Hardness and Compressive Response of Magnesium by Reinforcing with Hollow Glass Microballoons.

PubMed

Manakari, Vyasaraj; Parande, Gururaj; Doddamani, Mrityunjay; Gupta, Manoj

2017-08-25

Magnesium (Mg)/glass microballoons (GMB) metal matrix syntactic foams (1.47-1.67 g/cc) were synthesized using a disintegrated melt deposition (DMD) processing route. Such syntactic foams are of great interest to the scientific community as potential candidate materials for the ever-changing demands in automotive, aerospace, and marine sectors. The synthesized composites were evaluated for their microstructural, thermal, and compressive properties. Results showed that microhardness and the dimensional stability of pure Mg increased with increasing GMB content. The ignition response of these foams was enhanced by ~22 °C with a 25 wt % GMB addition to the Mg matrix. The authors of this work propose a new parameter, ignition factor, to quantify the superior ignition performance that the developed Mg foams exhibit. The room temperature compressive strengths of pure Mg increased with the addition of GMB particles, with Mg-25 wt % GMB exhibiting the maximum compressive yield strength (CYS) of 161 MPa and an ultimate compressive strength (UCS) of 232 MPa for a GMB addition of 5 wt % in Mg. A maximum failure strain of 37.7% was realized in Mg-25 wt % GMB foam. The addition of GMB particles significantly enhanced the energy absorption by ~200% prior to compressive failure for highest filler loading, as compared to pure Mg. Finally, microstructural changes in Mg owing to the presence of hollow GMB particles were elaborately discussed.

Theoretical Prediction of Microgravity Ignition Delay of Polymeric Fuels in Low Velocity Flows

NASA Technical Reports Server (NTRS)

Fernandez-Pello, A. C.; Torero, J. L.; Zhou, Y. Y.; Walther, D.; Ross, H. D.

2001-01-01

A new flammability apparatus and protocol, FIST (Forced Flow Ignition and Flame Spread Test), is under development. Based on the LIFT (Lateral Ignition and Flame Spread Test) protocol, FIST better reflects the environments expected in spacebased facilities. The final objective of the FIST research is to provide NASA with a test methodology that complements the existing protocol and provides a more comprehensive assessment of material flammability of practical materials for space applications. Theoretical modeling, an extensive normal gravity data bank and a few validation space experiments will support the testing methodology. The objective of the work presented here is to predict the ignition delay and critical heat flux for ignition of solid fuels in microgravity at airflow velocities below those induced in normal gravity. This is achieved through the application of a numerical model previously developed of piloted ignition of solid polymeric materials exposed to an external radiant heat flux. The model predictions will provide quantitative results about ignition of practical materials in the limiting conditions expected in space facilities. Experimental data of surface temperature histories and ignition delay obtained in the KC-135 aircraft are used to determine the critical pyrolysate mass flux for ignition and this value is subsequently used to predict the ignition delay and the critical heat flux for ignition of the material. Surface temperature and piloted ignition delay calculations for Polymethylmethacrylate (PMMA) and a Polypropylene/Fiberglass (PP/GL) composite were conducted under both reduced and normal gravity conditions. It was found that ignition delay times are significantly shorter at velocities below those induced by natural convection.

Evaluating free vs bound oxygen on ignition of nano-aluminum based energetics leads to a critical reaction rate criterion

NASA Astrophysics Data System (ADS)

Zhou, Wenbo; DeLisio, Jeffery B.; Wang, Xizheng; Egan, Garth C.; Zachariah, Michael R.

2015-09-01

This study investigates the ignition of nano-aluminum (n-Al) and n-Al based energetic materials (nanothermites) at varying O2 pressures (1-18 atm), aiming to differentiate the effects of free and bound oxygen on ignition and to assess if it is possible to identify a critical reaction condition for ignition independent of oxygen source. Ignition experiments were conducted by rapidly heating the samples on a fine Pt wire at a heating rate of ˜105 °C s-1 to determine the ignition time and temperature. The ignition temperature of n-Al was found to reduce as the O2 pressure increased, whereas the ignition temperatures of nanothermites (n-Al/Fe2O3, n-Al/Bi2O3, n-Al/K2SO4, and n-Al/K2S2O8) had different sensitivities to O2 pressure depending on the formulations. A phenomenological kinetic/transport model was evaluated to correlate the concentrations of oxygen both in condensed and gaseous phases, with the initiation rate of Al-O at ignition temperature. We found that a constant critical reaction rate (5 × 10-2 mol m-2 s-1) for ignition exists which is independent to ignition temperature, heating rate, and free vs bound oxygen. Since for both the thermite and the free O2 reaction the critical reaction rate for ignition is the same, the various ignition temperatures are simply reflecting the conditions when the critical reaction rate for thermal runaway is achieved.

Experimental and modeling study on effects of N2 and CO2 on ignition characteristics of methane/air mixture

PubMed Central

Zeng, Wen; Ma, Hongan; Liang, Yuntao; Hu, Erjiang

2014-01-01

The ignition delay times of methane/air mixture diluted by N2 and CO2 were experimentally measured in a chemical shock tube. The experiments were performed over the temperature range of 1300–2100 K, pressure range of 0.1–1.0 MPa, equivalence ratio range of 0.5–2.0 and for the dilution coefficients of 0%, 20% and 50%. The results suggest that a linear relationship exists between the reciprocal of temperature and the logarithm of the ignition delay times. Meanwhile, with ignition temperature and pressure increasing, the measured ignition delay times of methane/air mixture are decreasing. Furthermore, an increase in the dilution coefficient of N2 or CO2 results in increasing ignition delays and the inhibition effect of CO2 on methane/air mixture ignition is stronger than that of N2. Simulated ignition delays of methane/air mixture using three kinetic models were compared to the experimental data. Results show that GRI_3.0 mechanism gives the best prediction on ignition delays of methane/air mixture and it was selected to identify the effects of N2 and CO2 on ignition delays and the key elementary reactions in the ignition chemistry of methane/air mixture. Comparisons of the calculated ignition delays with the experimental data of methane/air mixture diluted by N2 and CO2 show excellent agreement, and sensitivity coefficients of chain branching reactions which promote mixture ignition decrease with increasing dilution coefficient of N2 or CO2. PMID:25750753

Thermal ignition combustion system

DOEpatents

Kamo, R.; Kakwani, R.M.; Valdmanis, E.; Woods, M.E.

1988-04-19

The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m C and a specific heat greater than 480 J/kg C with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber. 8 figs.

Thermal ignition combustion system

DOEpatents

Kamo, Roy; Kakwani, Ramesh M.; Valdmanis, Edgars; Woods, Melvins E.

1988-01-01

The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m.degree. C. and a specific heat greater than 480 J/kg.degree. C. with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber.

Dual coil ignition system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huberts, Garlan J.; Qu, Qiuping; Czekala, Michael Damian

2017-03-28

A dual coil ignition system is provided. The dual coil ignition system includes a first inductive ignition coil including a first primary winding and a first secondary winding, and a second inductive ignition coil including a second primary winding and a second secondary winding, the second secondary winding connected in series to the first secondary winding. The dual coil ignition system further includes a diode network including a first diode and a second diode connected between the first secondary winding and the second secondary winding.

An ignition key for atomic-scale engines

NASA Astrophysics Data System (ADS)

Dundas, Daniel; Cunningham, Brian; Buchanan, Claire; Terasawa, Asako; Paxton, Anthony T.; Todorov, Tchavdar N.

2012-10-01

A current-carrying resonant nanoscale device, simulated by non-adiabatic molecular dynamics, exhibits sharp activation of non-conservative current-induced forces with bias. The result, above the critical bias, is generalized rotational atomic motion with a large gain in kinetic energy. The activation exploits sharp features in the electronic structure, and constitutes, in effect, an ignition key for atomic-scale motors. A controlling factor for the effect is the non-equilibrium dynamical response matrix for small-amplitude atomic motion under current. This matrix can be found from the steady-state electronic structure by a simpler static calculation, providing a way to detect the likely appearance, or otherwise, of non-conservative dynamics, in advance of real-time modelling.

Factor analysis of submicron particle size distributions near a major United States-Canada trade bridge.

PubMed

Ogulei, David; Hopke, Philip K; Ferro, Andrea R; Jaques, Peter A

2007-02-01

A factor analytic model has been applied to resolve and apportion particles based on submicron particle size distributions downwind of a United States-Canada bridge in Buffalo, NY. The sites chosen for this study were located at gradually increasing distances downwind of the bridge complex. Seven independent factors were resolved, including four factors that were common to all of the five sites considered. The common factors were generally characterized by the existence of two or more number and surface area modes. The seven factors resolved were identified as follows: fresh tail-pipe diesel exhaust, local/street diesel traffic, aged/evolved diesel particles, spark-ignition gasoline emissions, background urban emissions, heavy-duty diesel agglomerates, and secondary/transported material. Submicron (<0.5 microm) and ultrafine (<0.1 microm) particle emissions downwind of the bridge were dominated by commercial diesel truck emissions. Thus, this study obtained size distinction between fresh versus aged vehicle exhaust and spark-ignition versus diesel emissions based on the measured high time-resolution particle number concentrations. Because this study mainly used particles <300 nm in diameter, some sources that would usually exhibit number modes >100 nm were not resolved. Also, the resolved profiles suggested that the major number mode for fresh tailpipe diesel exhaust might exist below the detection limit of the spectrometer used. The average particle number contributions from the resolved factors were highest closest to the bridge.

Experimental investigations of the minimum ignition energy and the minimum ignition temperature of inert and combustible dust cloud mixtures.

PubMed

Addai, Emmanuel Kwasi; Gabel, Dieter; Krause, Ulrich

2016-04-15

The risks associated with dust explosions still exist in industries that either process or handle combustible dust. This explosion risk could be prevented or mitigated by applying the principle of inherent safety (moderation). This is achieved by adding an inert material to a highly combustible material in order to decrease the ignition sensitivity of the combustible dust. The presented paper deals with the experimental investigation of the influence of adding an inert dust on the minimum ignition energy and the minimum ignition temperature of the combustible/inert dust mixtures. The experimental investigation was done in two laboratory scale equipment: the Hartmann apparatus and the Godbert-Greenwald furnace for the minimum ignition energy and the minimum ignition temperature test respectively. This was achieved by mixing various amounts of three inert materials (magnesium oxide, ammonium sulphate and sand) and six combustible dusts (brown coal, lycopodium, toner, niacin, corn starch and high density polyethylene). Generally, increasing the inert materials concentration increases the minimum ignition energy as well as the minimum ignition temperatures until a threshold is reached where no ignition was obtained. The permissible range for the inert mixture to minimize the ignition risk lies between 60 to 80%. Copyright © 2016 Elsevier B.V. All rights reserved.

Experimental investigation on ignition schemes of partially covered cavities in a supersonic flow

NASA Astrophysics Data System (ADS)

Cai, Zun; Sun, Mingbo; Wang, Hongbo; Wang, Zhenguo

2016-04-01

In this study, ignition schemes of the partially covered cavity in a scramjet combustor were investigated under inflow conditions of Ma=2.1 with stagnation pressure P0=0.7 Mpa and stagnation temperature T0=947 K. It reveals that the ignition scheme of the partially covered cavity has a great impact on the ignition and flame stabilization process. There always exists an optimized global equivalence ratio of a fixed ignition scheme, and the optimized global equivalence ratio of ignition in the partially covered cavity is lower than that of the uncovered cavity. For tandem dual-cavities, ignition in the partially covered cavity could be enhanced with the optimization of global equivalence ratio. However, ignition in the partially covered cavity would be exacerbated with further increasing the global equivalence ratio. The global equivalence ratio and the jet penetration height have a strong coupling with the combustion flow-field. For multi-cavities, it is assured that fuel injection on the opposite side could hardly be ignited after ignition in the partially covered cavity even with the optimized global equivalence ratio. It is possible to realize ignition enhancement in the partially covered cavity with the optimization of global equivalence ratio, but it is not beneficial for thrust increment during the steady combustion process.

Avian influenza A (H5N1).

PubMed

de Jong, Menno D; Hien, Tran Tinh

2006-01-01

Since their reemergence in 2003, highly pathogenic avian influenza A (H5N1) viruses have reached endemic levels among poultry in several southeast Asian countries and have caused a still increasing number of more than 100 reported human infections with high mortality. These developments have ignited global fears of an imminent influenza pandemic. The current knowledge of the virology, clinical spectrum, diagnosis and treatment of human influenza H5N1 virus infections is reviewed herein.

Measurement of Ti-6Al-4V alloy ignition temperature by reflectivity detection

NASA Astrophysics Data System (ADS)

Wang, C.; Hu, J.; Wang, F.; Jiang, J.; Zhang, Z. Z.; Yang, Y.; Ding, J. X.; Jiang, H. C.; Wang, Y. M.; Wei, H. Y.

2018-04-01

Fires resulting from titanium combustion are complex and violent processes which can instantly burn a titanium alloy once ignited. The occurrence of titanium combustion is a disaster for aircraft. Accurate measurement of the ignition temperature of titanium alloys is of significance in preventing such fires and in investigating combustion-resistance properties. In this study, monochromatic temperature and emissivity measurement methods based on reflectivity detection were used to determine the ignition temperature of a titanium alloy. Experiments were carried out using a titanium burning apparatus. The temperatures of titanium in the oxidation stage before ignition and in the combustion stage during the ignition process were measured using wavelengths of 1050 nm and 940 nm, respectively. Experimental results showed that the ignition temperature of the titanium alloy could be measured by reflectivity detection and that measurement precision during thermal oxidation (500-900 °C) was ±1 °C. The temperature of the ignition process ranged between 1653 and 1857 °C, and the ignition temperature was around 1680 °C.

Measurement of Ti-6Al-4V alloy ignition temperature by reflectivity detection.

PubMed

Wang, C; Hu, J; Wang, F; Jiang, J; Zhang, Z Z; Yang, Y; Ding, J X; Jiang, H C; Wang, Y M; Wei, H Y

2018-04-01

Fires resulting from titanium combustion are complex and violent processes which can instantly burn a titanium alloy once ignited. The occurrence of titanium combustion is a disaster for aircraft. Accurate measurement of the ignition temperature of titanium alloys is of significance in preventing such fires and in investigating combustion-resistance properties. In this study, monochromatic temperature and emissivity measurement methods based on reflectivity detection were used to determine the ignition temperature of a titanium alloy. Experiments were carried out using a titanium burning apparatus. The temperatures of titanium in the oxidation stage before ignition and in the combustion stage during the ignition process were measured using wavelengths of 1050 nm and 940 nm, respectively. Experimental results showed that the ignition temperature of the titanium alloy could be measured by reflectivity detection and that measurement precision during thermal oxidation (500-900 °C) was ±1 °C. The temperature of the ignition process ranged between 1653 and 1857 °C, and the ignition temperature was around 1680 °C.

Ignition Delay Associated with a Strained Strip

NASA Technical Reports Server (NTRS)

Gerk, T. J.; Karagozian, A. R.

1996-01-01

Ignition processes associated with two adjacent fuel-oxidizer interferences bounding a strained fuel strip are explored here using single-step activation energy asymptotics. Calculations are made for constant as well as temporally decaying strain fields. There possible models of ignition are determined: one in which the two interfaces ignite independently as diffusion flames; one in which the two interfaces ignite dependently and in which ignition occurs to form a single , premixed flame at very high strain rates before ignition is completely prevented. In contrast to a single, isolated interface in which ignition can be prevented by overmatching heat production with heat convection due to strain, ignition of a strained fuel strip can also be prevented if the finite extend of fuel is diluted by oxidizer more quickly than heat production can cause a positive feedback thermal runaway. These behaviors are dependent on the relative sizes of timescales associated with species and heat diffusion, with convection due to strain, and with the chemical reaction. The result here indicate that adjacent, strained species interfaces may ignite quite differently in nature from ignition of a single, strained intrface and that their interdependence should be considered as the interfaces are brought closer together in complex strain fields. Critical strain rates leading to complete ignition delay are found to be considerably smaller for the fuel strip than those for single interfaces as the fuel strip is made thin in comparison to diffusion and chemical length scales.

Relation Between Inflammables and Ignition Sources in Aircraft Environments

NASA Technical Reports Server (NTRS)

Scull, Wilfred E

1950-01-01

A literature survey was conducted to determine the relation between aircraft ignition sources and inflammables. Available literature applicable to the problem of aircraft fire hazards is analyzed and, discussed herein. Data pertaining to the effect of many variables on ignition temperatures, minimum ignition pressures, and minimum spark-ignition energies of inflammables, quenching distances of electrode configurations, and size of openings incapable of flame propagation are presented and discussed. The ignition temperatures and the limits of inflammability of gasoline in air in different test environments, and the minimum ignition pressure and the minimum size of openings for flame propagation of gasoline - air mixtures are included. Inerting of gasoline - air mixtures is discussed.

Mencius' Educational Philosophy and Its Contemporary Relevance

ERIC Educational Resources Information Center

Huang, Chun-chieh

2014-01-01

This article argues that Mencius' education is "holistic education" that aims at igniting the "silent revolution" from within one's inner mind-heart to be unfolded in society, state, and the world. Mencius' educational philosophy is based on his theory of human nature and his theory of self-cultivation. Mencius…

Emissions from an automobile fire.

PubMed

Lönnermark, Anders; Blomqvist, Per

2006-02-01

The emissions from automobile fires have been investigated. The main gas phase components were analysed in small-scale tests with representative material from an automobile. A more detailed investigation of full-scale simulated automobile fires was also conducted, including the characterisation of gas phase components, particulates and run-off water from extinguishing activities. Three separate full scale fire tests have been characterised: a fire ignited and developed in the engine compartment; a fire ignited inside the coupé, that was extinguished in the early stages; and a similar fire ignited inside the coupé that was allowed to spread until the entire vehicle was involved in the fire. The quantitative analysis of the smoke gases from the full-scale fires showed that emissions with a potentially negative impact on the environment, or chronic toxic effect on humans, were produced in significant quantities. These emissions included HCl, SO2, VOCs (e.g. benzene), PAHs, and PCDDs/PCDFs. Analysis of run-off water indicated that it was severely contaminated, containing elevated levels of both organic compounds and metals. Comparison with data from other vehicle fires found in the literature shows that contamination by lead, copper, zinc, and antimony appears to be significant in water run-off from these types of fires.

Ignition patterns & prescribed fire behavior in southern pine stands

Treesearch

Ragnar W. Johansen

1987-01-01

As an aid to forest managers who use or contemplate using aerial ignition techniques in their prescribed burning programs, a study was designed to evaluate the magnitude of the differences that could occur depending on whether lines of fire were used (ignited by a helitorch) or a spot-fire technique was used (ignited by aerial ignition devices). Six experimental fires...

LOX/Methane Main Engine Glow Plug Igniter Tests and Modeling

NASA Technical Reports Server (NTRS)

Breisacher, Kevin; Ajmani, Kumud

2009-01-01

Ignition data for tests with a LOX/methane igniter that utilized a glow plug as the ignition source are presented. The tests were conducted in a vacuum can with thermally conditioned (cold) hardware. Data showing the effects of glow plug geometry, type, and igniter operating conditions are discussed. Comparisons between experimental results and multidimensional, transient computer models are also made.

Transition from Ignition to Flame Growth under External Radiation in Three Dimensions (TIGER-3D)

NASA Technical Reports Server (NTRS)

Kashiwagi, Takashi; Nakamura, Yuji; Olson, Sandra L.; Mell, William

2004-01-01

This study focuses on localized ignition by external radiant flux and subsequent flame growth over thin polymeric materials (plastic and paper) in microgravity. Two transition stages were observed. The first transition stage covers the period from the onset of ignition to the formation of stabilized flame near the ignited area. This is followed by the second transition of the flame growth stage from the initial stabilized flame to sustained fire growth away from the ignited area. For the first stage, ignition experiments of thin PMMA sheets were conducted using a CO2 laser as an external source in the 10 s drop tower. The results of front side surface ignition and of backside surface ignition were observed. The effects of imposed flow velocity, sample thickness, and ambient oxygen concentration on ignition are obtained. Numerical study was conducted to investigate to understand and predict ignition behavior observed in the experiments. For the second stage, numerical study is being conducted to describe the effects of gravity on heat release rate of a PMMA sheet. The gravity level was varied from zero to normal gravity. The preliminary results show that the maximum heat release occurs at around 0.02 g.

Transition from Ignition to Flame Growth under External Radiation in 3D

NASA Technical Reports Server (NTRS)

Kashiwagi, Takashi; Nakamura, Yuji; Mell, William E.; Olson, Sandra L.

2004-01-01

This study focuses on localized ignition by external radiant flux and subsequent flame growth over thin polymeric materials (plastic and paper) in microgravity. Two transition stages were observed. The first transition stage covers the period from the onset of ignition to the formation of stabilized flame near the ignited area. This is followed by the second transition of the flame growth stage from the initial stabilized flame to sustained fire growth away from the ignited area. For the first stage, ignition experiments of thin PMMA sheets were conducted using a CO2 laser as an external source in the 10 s drop tower. The results of front side surface ignition and of backside surface ignition were observed. The effects of imposed flow velocity, sample thickness, and ambient oxygen concentration on ignition are obtained. Numerical study was conducted to investigate to understand and predict ignition behavior observed in the experiments. For the second stage, numerical study is being conducted to describe the effects of gravity on heat release rate of a PMMA sheet. The gravity level was varied from zero to normal gravity. The preliminary results show that the maximum heat release occurs at around 0.02 g.

The Effect of Particle Properties on Hot Particle Spot Fire Ignition

NASA Astrophysics Data System (ADS)

Zak, Casey David

The ignition of natural combustible material by hot metal particles is an important fire ignition pathway by which wildland and wildland-urban-interface spot fires are started. There are numerous cases reported of wild fires started by clashing power-lines or from sparks generated by machines or engines. Similarly there are many cases reported of fires caused by grinding, welding and cutting sparks. Up to this point, research on hot particle spot fire ignition has largely focused on particle generation and transport. A small number of studies have examined what occurs after a hot particle contacts a natural fuel bed, but until recently the process remained poorly understood. This work describes an investigation of the effect of particle size, temperature and thermal properties on the ability of hot particles to cause flaming ignition of cellulosic fuel beds. Both experimental and theoretical approaches are used, with a focus on understanding the physics underlying the ignition process. For the experimental study, spheres of stainless steel, aluminum, brass and copper are heated in a tube furnace and dropped onto a powdered cellulose fuel bed; the occurrence of flaming ignition or lack thereof is visually observed and recorded. This procedure is repeated a large number of times for each metal type, varying particle diameter from 2 to 11 mm and particle temperature between 575 and 1100°C. The results of these experiments are statistically analyzed to find approximate ignition boundaries and identify boundary trends with respect to the particle parameters of interest. Schlieren images recorded during the ignition experiments are also used to more accurately describe the ignition process. Based on these images, a simple theoretical model of hot particle spot fire ignition is developed and used to explore the experimental trends further. The model under-predicts the minimum ignition temperatures required for small spheres, but agrees qualitatively with the experimental data. Model simulations identify the important physics controlling ignition for different sized particles and clarify many of the experimental trends. The results show a hyperbolic relationship between particle size and temperature, with the larger particles requiring lower temperatures to ignite the cellulose than the smaller particles. For very small spheres, the temperature required for ignition is very sensitive to particle size, while for very large spheres, ignition temperature shows only a weak dependence on that variable. Flaming ignition of powdered cellulose by particles ≤ 11 mm in size requires particle temperatures of at least 600°C. Ignition has not been observed for 2 mm particles at temperatures up to 1100°C, but the statistical analysis indicates that ignition by particles 2 mm and smaller may be possible at temperatures above 950°C. No clear trend is observed with particle metal type, but copper particles require slightly higher ignition temperatures and seem more sensitive to experimental variation, likely due to their relatively high thermal conductivity. High-speed Schlieren images taken during the ignition experiments show that once particles land, they volatilize the powdered cellulose and the fuel vapor diffuses out into the surrounding air. Ignition occurs in the mixing layer between the vapor and the air, either during the initial expansion of the pyrolyzate away from the particle, or after a stable plume of volatiles has formed. Modeling results indicate that in the large-particle, high-conductivity limit, the particle's surface temperature remains close to its impact temperature over the timescales of ignition. As a result, particle thermal properties are unimportant and ignition occurs when heat generation in the mixing layer overcomes losses to the surrounding air. When the large-particle limit does not apply, the particle cools upon impact with the fuel bed. In addition to the losses to the surrounding air, the reaction zone experiences losses to the cooling particle and must generate a larger amount of heat for ignition to occur. Because cooling is so important, the initial bulk energy is more useful than impact temperature for predicting ignition by smaller particles. Along those lines, the additional heat of melting available to molten particles helps to resist particle cooling; as such, molten aluminum particles 3.5 -- 7 mm in diameter can ignite at lower temperatures than solid particles of the same size with similar thermal properties. Decreasing volumetric heat capacity does increase minimum ignition temperature somewhat, but this effect is reduced for larger particles. Emissivity does not appear to have a significant effect on ignition propensity, suggesting that, over the timescales of ignition, radiation heat transfer is small relative to other modes of particle heat loss.

Effect of oxygen on the ignition of liquid fuels

NASA Technical Reports Server (NTRS)

Pahl, H

1929-01-01

The ignition temperature, ignition lag, and ignition strength of simple and homogeneous fuels in combustion air of small oxygen content differ from what they are in air of greater oxygen content. In the case of small oxygen content, these fuels behave as if mixed unevenly. In the case of air with a definite oxygen content, the simple fuels have two ignition points, between which ignition takes place within a certain temperature range. The phenomena are explained by pyrogenous decomposition, comparison of the individual heat quantities, and the effect of the walls.

Laser ignition application in a space experiment

NASA Technical Reports Server (NTRS)

Liou, Larry C.; Culley, Dennis E.

1993-01-01

A laser ignition system is proposed for the Combustion Experiment Module on an orbiting spacecraft. The results of a design study are given using the scheduled 'Flame Ball Experiment' as the design guidelines. Three laser ignition mechanisms and wavelengths are evaluated. A prototype laser is chosen and its specifications are given, followed by consideration of the beam optical arrangement, the ignition power requirement, the laser ignition system weight, size, reliability, and laser cooling and power consumption. Electromagnetic interference to the onboard electronics caused by the laser ignition process is discussed. Finally, ground tests are suggested.

The influence of lightning activity and anthropogenic factors on large-scale characteristics of natural fires

NASA Astrophysics Data System (ADS)

Eliseev, A. V.; Mokhov, I. I.; Chernokulsky, A. V.

2017-01-01

A module for simulating of natural fires (NFs) in the climate model of the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM), is extended with respect to the influence of lightning activity and population density on the ignition frequency and fire suppression. The IAP RAS CM is used to perform numerical experiments in accordance with the conditions of the project that intercompares climate models, CMIP5 (Coupled Models Intercomparison Project, phase 5). The frequency of lightning flashes was assigned in accordance with the LIS/OTD satellite data. In the calculations performed, anthropogenic ignitions play an important role in NF occurrences, except for regions at subpolar latitudes and, to a lesser degree, tropical and subtropical regions. Taking into account the dependence of fire frequency on lightning activity and population density intensifies the influence of characteristics of natural fires on the climate changes in tropics and subtropics as compared to the version of the IAP RAS CM that does not take the influence of ignition sources on the large-scale characteristics of NFs into consideration.

Breakdown characteristics of atmospheric dielectric barrier discharge in gas flow condition

NASA Astrophysics Data System (ADS)

Fan, Zhihui; Yan, Huijie; Wang, Yuying; Liu, Yidi; Guo, Hongfei; Ren, Chunsheng

2018-05-01

Experimental investigations of the breakdown characteristics of plate-to-plate dielectric barrier discharge excited by an AC source at different gas flow conditions are carried out. The ignition voltage for the appearance of the very first discharge filament and the breakdown voltage in each discharge half cycle in continuous operation are examined. As revealed by the results of the indoor air experiment, the ignition voltage manifests a monotonous increase with the increase in the gas flow rate, while the breakdown voltage has a marked decline at the low gas flow rate and increases slightly as the gas flow rate is higher than 10 m/s. As regards the obvious decreases in the ignition voltage and breakdown voltage, the decrease in the humidity with the increase in the gas flow rate plays a dominant role. As regards the increase in breakdown voltage, the memory effect from the preceding discharge is considered. The losses of metastable particles, together with particles having high translational energy in the gas flow, are considered to be the most critical factors.

Asphalt binder grade selection and ignition oven calibration factors for HMAC with recycled asphalt products.

DOT National Transportation Integrated Search

2013-02-01

This study investigated several characteristics of laboratory-fabricated and plant-produced hot-mix asphalt mixtures containing : various proportions of RAP and RAS with the principal objectives of developing a procedure for selecting the virgin bind...

Experimental study on the minimum ignition temperature of coal dust clouds in oxy-fuel combustion atmospheres.

PubMed

Wu, Dejian; Norman, Frederik; Verplaetsen, Filip; Van den Bulck, Eric

2016-04-15

BAM furnace apparatus tests were conducted to investigate the minimum ignition temperature of coal dusts (MITC) in O2/CO2 atmospheres with an O2 mole fraction from 20 to 50%. Three coal dusts: Indonesian Sebuku coal, Pittsburgh No.8 coal and South African coal were tested. Experimental results showed that the dust explosion risk increases significantly with increasing O2 mole fraction by reducing the minimum ignition temperature for the three tested coal dust clouds dramatically (even by 100°C). Compared with conventional combustion, the inhibiting effect of CO2 was found to be comparatively large in dust clouds, particularly for the coal dusts with high volatile content. The retardation effect of the moisture content on the ignition of dust clouds was also found to be pronounced. In addition, a modified steady-state mathematical model based on heterogeneous reaction was proposed to interpret the observed experimental phenomena and to estimate the ignition mechanism of coal dust clouds under minimum ignition temperature conditions. The analysis revealed that heterogeneous ignition dominates the ignition mechanism for sub-/bituminous coal dusts under minimum ignition temperature conditions, but the decrease of coal maturity facilitates homogeneous ignition. These results improve our understanding of the ignition behaviour and the explosion risk of coal dust clouds in oxy-fuel combustion atmospheres. Copyright © 2015 Elsevier B.V. All rights reserved.

Ignition study of a petrol/CNG single cylinder engine

NASA Astrophysics Data System (ADS)

Khan, N.; Saleem, Z.; Mirza, A. A.

2005-11-01

Benefits of laser ignition over the electrical ignition system for Compressed Natural Gas (CNG) engines have fuelled automobile industry and led to an extensive research on basic characteristics to switch over to the emerging technologies. This study was undertaken to determine the electrical and physical characteristics of the electric spark ignition of single cylinder petrol/CNG engine to determine minimum ignition requirements and timeline of ignition events to use in subsequent laser ignition study. This communication briefly reviews the ongoing research activities and reports the results of this experimental study. The premixed petrol and CNG mixtures were tested for variation of current and voltage characteristics of the spark with speed of engine. The current magnitude of discharge circuit was found to vary linearly over a wide range of speed but the stroke to stroke fire time was found to vary nonlinearly. The DC voltage profiles were observed to fluctuate randomly during ignition process and staying constant in rest of the combustion cycle. Fire to fire peaks of current amplitudes fluctuated up to 10% of the peak values at constant speed but increased almost linearly with increase in speed. Technical barriers of laser ignition related to threshold minimum ignition energy, inter-pulse durations and firing sequence are discussed. Present findings provide a basic initiative and background information for designing suitable timeline algorithms for laser ignited leaner direct injected CNG engines.

Ignition Characterization Test Results for the LO2/Ethanol Propellant Combination

NASA Technical Reports Server (NTRS)

Robinson, Philip J.; Popp, Christopher G.; veith, Eric M.

2007-01-01

A series of contracts were issued by the Marshall Space Flight Center (MSFC) of the National Aeronautics and Space Administration (NASA) un der the auspices of the Exploration Systems Mission Directorate to de velop and expand the maturity of candidate technologies considered to be important for future space exploration. One such technology was to determine the viability of incorporating non-toxic propellants for R eaction Control Subsystems (RCS). Contract NAS8-01109 was issued to A erojet to develop a dual thrust Reaction Control Engine (RCE) that ut ilized liquid oxygen and ethanol as the propellants. The dual thrust RCE incorporated a primary thrust level of 870 lbf, and a vernier thru st level of 10 - 30 lbf. The preferred RCS approach for the dual thru st RCE was to utilize pressure-fed liquid oxygen (LOX) and ethanol pr opellants; however, previous dual thrust feasibility testing incorporated GOX/Ethanol igniters as opposed to LOX/Ethanol igniters in the de sign. GOX/Ethanol was easier to ignite, but this combination had syst em design implications of providing GOX for the igniters. A LOX/Ethan ol igniter was desired; however, extensive LOX/Ethanol ignition data over the anticipated operating range for the dual thrust RCE did not e xist. Therefore, Aerojet designed and tested a workhorse LOX igniter to determine LOX/Ethanol ignition characteristics as part of a risk m itigation effort for the dual thrust RCE design. The objective of the ignition testing was to demonstrate successful ignition from GOX to LOX, encompassing potential two-phase flow conditions anticipated being present in real mission applications. A workhorse igniter was desig ned to accommodate the full LOX design flowrate, as well as a reduced GOX flowrate. It was reasoned that the initial LOX flow through the igniter would flash to GOX due to the latent heat stored in the hardwa re, causing a reduced oxygen flowrate because of a choked, or sonic, flow condition through the injection elements. As LOX flow continued, the hardware would chill-in, with the injected oxygen flow transitioning from cold GOX through two'phase flow to subcooled LOX. The Workh orse igniter was well instrumented: Pressure and temperature instrumentation permitted oxygen state points to be determined in the igniter oxidizer manifold, and gas-side igniter chamber thermocouples provide d chamber thermal profile characteristics. The cold flow chamber pres sure (Pc) for each test was determined and coupled with the igniter chamber diameter (De) to calculate the characteristic quench parameter (Pc x Dc), which was plotted as a function of core mixture ratio, MRc . Ignition limits were determined over a broad range of valve inlet conditions, and ignition was demonstrated with oxygen inlet conditions that ranged from subcooled 210 deg R LOX to 486 deg R GOX. Once ign ited at cold GOX conditions, combustion was continuous as the hardwar e chilled in and the core mixture ratio transitioned from values near 1.0 to over 12.5. Pulsing is required in typical RCS engines; therefore, the workhorse igniter was pulse tested to verify the ability to pr ovide the required ignition for a pulsing RCE. The minimum electrical pulse width (EPW) of the dual thrust RCE was 0.080 seconds. Igniter pulse tests were performed at three conditions: (1) an EPW of 0.080 se conds at 25% duty cycle for 400 pulses; (2) an EPW of 0.160 seconds a nd a 5% duty cycle for 124 pulses; (3) an EPW of 0.160 seconds and a 50% duty cycle for 380 pulses. Successful ignition of LOX/Ethanol was demonstrated over a broad range of valve inlet conditions, with the empirically determined LOX/Ethanol ignition limits extending the previous database established for GOX/Ethanol ignition limits. Although th e observed chill-in characteristics of the hardware varied significan tly with flowrate, ignition was readily achieved. Combustion was marg inal at extremely fuel-rich conditions, and it fluctuated as the oxygen passed rough the twophase flow regime during the period of hardware chill-in. Pulse testing showed good repeatability with 100 percent r e-ignition for all pulses. Certain pulse-to-pulse repeatability requirements for actual RCS operation may necessitate establishment of mini mum oxygen flow rates and engine thrust levels for satisfactory engin e performance.

Ignition improvement by injector arrangement in a multi-fuel combustor for micro gas turbine

NASA Astrophysics Data System (ADS)

Antoshkiv, O.; Poojitganont, T.; Jeansirisomboon, S.; Berg, H. P.

2018-01-01

The novel combustor design also has an impact on the ignitor arrangement. The conventional ignitor system cannot guarantee optimal ignition performance in the usual radial position. The difficult ignitability of gaseous fuels was the main challenge for the ignitor system improvement. One way to improve the ignition performance significantly is a torch ignitor system in which the gaseous fuel is directly mixed with a large amount of the combustor air. To reach this goal, the ignition process was investigated in detail. The micro gas turbine (MGT) ignition was optimised considering three main procedures: torch ignitor operation, burner ignition and flame propagation between the neighbour injectors. A successful final result of the chain of ignition procedures depends on multiple aspects of the combustor design. Performed development work shows an important step towards designing modern high-efficiency low-emission combustors.

Temperature analysis of laser ignited metalized material using spectroscopic technique

NASA Astrophysics Data System (ADS)

Bassi, Ishaan; Sharma, Pallavi; Daipuriya, Ritu; Singh, Manpreet

2018-05-01

The temperature measurement of the laser ignited aluminized Nano energetic mixture using spectroscopy has a great scope in in analysing the material characteristic and combustion analysis. The spectroscopic analysis helps to do in depth study of combustion of materials which is difficult to do using standard pyrometric methods. Laser ignition was used because it consumes less energy as compared to electric ignition but ignited material dissipate the same energy as dissipated by electric ignition and also with the same impact. Here, the presented research is primarily focused on the temperature analysis of energetic material which comprises of explosive material mixed with nano-material and is ignited with the help of laser. Spectroscopy technique is used here to estimate the temperature during the ignition process. The Nano energetic mixture used in the research does not comprise of any material that is sensitive to high impact.

Numerical Analysis of the Interaction between Thermo-Fluid Dynamics and Auto-Ignition Reaction in Spark Ignition Engines

NASA Astrophysics Data System (ADS)

Saijyo, Katsuya; Nishiwaki, Kazuie; Yoshihara, Yoshinobu

The CFD simulations were performed integrating the low-temperature oxidation reaction. Analyses were made with respect to the first auto-ignition location in the case of a premixed-charge compression auto-ignition in a laminar flow field and in the case of the auto-ignition in an end gas during an S. I. Engine combustion process. In the latter simulation, the spatially-filtered transport equations were solved to express fluctuating temperatures in a turbulent flow in consideration of strong non-linearity to temperature in the reaction equations. It is suggested that the first auto-ignition location does not always occur at higher-temperature locations and that the difference in the locations of the first auto-ignition depends on the time period during which the local end gas temperature passes through the region of shorter ignition delay, including the NTC region.

Generalized Lawson Criteria for Inertial Confinement Fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tipton, Robert E.

2015-08-27

The Lawson Criterion was proposed by John D. Lawson in 1955 as a general measure of the conditions necessary for a magnetic fusion device to reach thermonuclear ignition. Over the years, similar ignition criteria have been proposed which would be suitable for Inertial Confinement Fusion (ICF) designs. This paper will compare and contrast several ICF ignition criteria based on Lawson’s original ideas. Both analytical and numerical results will be presented which will demonstrate that although the various criteria differ in some details, they are closely related and perform similarly as ignition criteria. A simple approximation will also be presented whichmore » allows the inference of each ignition parameter directly from the measured data taken on most shots fired at the National Ignition Facility (NIF) with a minimum reliance on computer simulations. Evidence will be presented which indicates that the experimentally inferred ignition parameters on the best NIF shots are very close to the ignition threshold.« less

Research on the Electro-explosive Behaviors and the Ignition Performances of Energetic Igniters

NASA Astrophysics Data System (ADS)

Li, Yong; Jia, Xin; Wang, Liu; Zhou, Bin; Shen, Ruiqi

2018-01-01

This article describes the electro-explosive behaviors and the ignition performances of energetic igniters based on the combination of polysilicon film with Al/CuO nanoenergetic multilayer films (nEMFs).The ultra-high-speed framing camera images show that melting first occurs at the V-type angles and then expands to the entire bridge. The Al/CuO nEMF is heated and fired from below, forced to form lots of flyers with different sizes, ejected with the expansion of polysilicon plasma, and reacts exothermically to release a large quantity of energy. Furthermore, temperature diagnosis results demonstrate higher temperature products of energetic igniters. Ignition experiment at a standoff of 1.5 mm results show that the average firing voltage and the variance of energetic igniters are 28.50 V and 0.96, whereas those of polysilicon igniters are 32.05 V and 1.94.

Convective Ignition of Propellant Cylinders in a Developing Cross-Flow Field.

DTIC Science & Technology

1980-09-01

Ignition. .. ...... ..... 69 (ii) Polymer Ignition .. ....... ....... 72 F . Flame Spreading and Blow -off Phenomena .. ...... 72 G. Ignition and Flame...polymeric fuel binder for mechanical integrity. It also includes solid additives (like aluminum) and various catalysts and plasticizing agents . Ballistic...placed on distinguishing the ignition sites and the flame spreading (and blow off) tendencies as functions of the external flow velocity pressure and

Surface breakdown igniter for mercury arc devices

DOEpatents

Bayless, John R.

1977-01-01

Surface breakdown igniter comprises a semiconductor of medium resistivity which has the arc device cathode as one electrode and has an igniter anode electrode so that when voltage is applied between the electrodes a spark is generated when electrical breakdown occurs over the surface of the semiconductor. The geometry of the igniter anode and cathode electrodes causes the igniter discharge to be forced away from the semiconductor surface.

Seasonality of Fire Weather Strongly Influences Fire Regimes in South Florida Savanna-Grassland Landscapes

PubMed Central

Platt, William J.; Orzell, Steve L.; Slocum, Matthew G.

2015-01-01

Fire seasonality, an important characteristic of fire regimes, commonly is delineated using seasons based on single weather variables (rainfall or temperature). We used nonparametric cluster analyses of a 17-year (1993–2009) data set of weather variables that influence likelihoods and spread of fires (relative humidity, air temperature, solar radiation, wind speed, soil moisture) to explore seasonality of fire in pine savanna-grassland landscapes at the Avon Park Air Force Range in southern Florida. A four-variable, three-season model explained more variation within fire weather variables than models with more seasons. The three-season model also delineated intra-annual timing of fire more accurately than a conventional rainfall-based two-season model. Two seasons coincided roughly with dry and wet seasons based on rainfall. The third season, which we labeled the fire season, occurred between dry and wet seasons and was characterized by fire-promoting conditions present annually: drought, intense solar radiation, low humidity, and warm air temperatures. Fine fuels consisting of variable combinations of pyrogenic pine needles, abundant C4 grasses, and flammable shrubs, coupled with low soil moisture, and lightning ignitions early in the fire season facilitate natural landscape-scale wildfires that burn uplands and across wetlands. We related our three season model to fires with different ignition sources (lightning, military missions, and prescribed fires) over a 13-year period with fire records (1997–2009). Largest wildfires originate from lightning and military ignitions that occur within the early fire season substantially prior to the peak of lightning strikes in the wet season. Prescribed ignitions, in contrast, largely occur outside the fire season. Our delineation of a pronounced fire season provides insight into the extent to which different human-derived fire regimes mimic lightning fire regimes. Delineation of a fire season associated with timing of natural lightning ignitions should be useful as a basis for ecological fire management of humid savanna-grassland landscapes worldwide. PMID:25574667

Seasonality of fire weather strongly influences fire regimes in South Florida savanna-grassland landscapes.

PubMed

Platt, William J; Orzell, Steve L; Slocum, Matthew G

2015-01-01

Fire seasonality, an important characteristic of fire regimes, commonly is delineated using seasons based on single weather variables (rainfall or temperature). We used nonparametric cluster analyses of a 17-year (1993-2009) data set of weather variables that influence likelihoods and spread of fires (relative humidity, air temperature, solar radiation, wind speed, soil moisture) to explore seasonality of fire in pine savanna-grassland landscapes at the Avon Park Air Force Range in southern Florida. A four-variable, three-season model explained more variation within fire weather variables than models with more seasons. The three-season model also delineated intra-annual timing of fire more accurately than a conventional rainfall-based two-season model. Two seasons coincided roughly with dry and wet seasons based on rainfall. The third season, which we labeled the fire season, occurred between dry and wet seasons and was characterized by fire-promoting conditions present annually: drought, intense solar radiation, low humidity, and warm air temperatures. Fine fuels consisting of variable combinations of pyrogenic pine needles, abundant C4 grasses, and flammable shrubs, coupled with low soil moisture, and lightning ignitions early in the fire season facilitate natural landscape-scale wildfires that burn uplands and across wetlands. We related our three season model to fires with different ignition sources (lightning, military missions, and prescribed fires) over a 13-year period with fire records (1997-2009). Largest wildfires originate from lightning and military ignitions that occur within the early fire season substantially prior to the peak of lightning strikes in the wet season. Prescribed ignitions, in contrast, largely occur outside the fire season. Our delineation of a pronounced fire season provides insight into the extent to which different human-derived fire regimes mimic lightning fire regimes. Delineation of a fire season associated with timing of natural lightning ignitions should be useful as a basis for ecological fire management of humid savanna-grassland landscapes worldwide.

Transformation of logwood combustion emissions in a smog chamber: formation of secondary organic aerosol and changes in the primary organic aerosol upon daytime and nighttime aging

NASA Astrophysics Data System (ADS)

Tiitta, Petri; Leskinen, Ari; Hao, Liqing; Yli-Pirilä, Pasi; Kortelainen, Miika; Grigonyte, Julija; Tissari, Jarkko; Lamberg, Heikki; Hartikainen, Anni; Kuuspalo, Kari; Kortelainen, Aki-Matti; Virtanen, Annele; Lehtinen, Kari E. J.; Komppula, Mika; Pieber, Simone; Prévôt, André S. H.; Onasch, Timothy B.; Worsnop, Douglas R.; Czech, Hendryk; Zimmermann, Ralf; Jokiniemi, Jorma; Sippula, Olli

2016-10-01

Organic aerosols (OA) derived from small-scale wood combustion emissions are not well represented by current emissions inventories and models, although they contribute substantially to the atmospheric particulate matter (PM) levels. In this work, a 29 m3 smog chamber in the ILMARI facility of the University of Eastern Finland was utilized to investigate the formation of secondary organic aerosol (SOA) from a small-scale modern masonry heater commonly used in northern Europe. Emissions were oxidatively aged in the smog chamber for a variety of dark (i.e., O3 and NO3) and UV (i.e., OH) conditions, with OH concentration levels of (0.5-5) × 106 molecules cm-3, achieving equivalent atmospheric aging of up to 18 h. An aerosol mass spectrometer characterized the direct OA emissions and the SOA formed from the combustion of three wood species (birch, beech and spruce) using two ignition processes (fast ignition with a VOC-to-NOx ratio of 3 and slow ignition with a ratio of 5).Dark and UV aging increased the SOA mass fraction with average SOA productions 2.0 times the initial OA mass loadings. SOA enhancement was found to be higher for the slow ignition compared with fast ignition conditions. Positive matrix factorization (PMF) was used to separate SOA, primary organic aerosol (POA) and their subgroups from the total OA mass spectra. PMF analysis identified two POA and three SOA factors that correlated with the three major oxidizers: ozone, the nitrate radical and the OH radical. Organonitrates (ONs) were observed to be emitted directly from the wood combustion and additionally formed during oxidation via NO3 radicals (dark aging), suggesting small-scale wood combustion may be a significant ON source. POA was oxidized after the ozone addition, forming aged POA, and after 7 h of aging more than 75 % of the original POA was transformed. This process may involve evaporation and homogeneous gas-phase oxidation as well as heterogeneous oxidation of particulate organic matter. The results generally prove that logwood burning emissions are the subject of intensive chemical processing in the atmosphere, and the timescale for these transformations is relatively short, i.e., hours.

Ignition and Inertial Confinement Fusion at The National Ignition Facility

NASA Astrophysics Data System (ADS)

Moses, Edward I.

2016-10-01

The National Ignition Facility (NIF), the world's largest and most powerful laser system for inertial confinement fusion (ICF) and for studying high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). The NIF is now conducting experiments to commission the laser drive, the hohlraum and the capsule and to develop the infrastructure needed to begin the first ignition experiments in FY 2010. Demonstration of ignition and thermonuclear bum in the laboratory is a major NIF goal. NIF will achieve this by concentrating the energy from the 192 beams into a mm3-sized target and igniting a deuterium-tritium mix, liberating more energy than is required to initiate the fusion reaction. NIP's ignition program is a national effort managed via the National Ignition Campaign (NIC). The NIC has two major goals: execution of DT ignition experiments starting in FY20l0 with the goal of demonstrating ignition and a reliable, repeatable ignition platform by the conclusion of the NIC at the end of FY2012. The NIC will also develop the infrastructure and the processes required to operate NIF as a national user facility. The achievement of ignition at NIF will demonstrate the scientific feasibility of ICF and focus worldwide attention on laser fusion as a viable energy option. A laser fusion-based energy concept that builds on NIF, known as LIFE (Laser Inertial Fusion Energy), is currently under development. LIFE is inherently safe and can provide a global carbon-free energy generation solution in the 21st century. This paper describes recent progress on NIF, NIC, and the LIFE concept.

Integrating micro-ignitors with Al/Bi2O3/graphene oxide composite energetic films to realize tunable ignition performance

NASA Astrophysics Data System (ADS)

Ma, Xiaoxia; Cheng, Shengxian; Hu, Yan; Ye, Yinghua; Shen, Ruiqi

2018-03-01

The integration of composite energetic films (CEFs) with various types of initiators can effectively adjust their performance and represents potential applications in microscale energy-demanding systems. In this study, the Al/Bi2O3/graphene oxide (GO) CEFs were successfully integrated into copper micro-ignitors by electrophoretic deposition, a low-cost and time-saving method. The effects of the Al/Bi2O3/GO CEFs with different GO contents on exothermic performance and ignition properties of micro-ignitors were then systematically investigated in terms of heat release, activation energy, ignition duration, the maximum height of the ignition product, and ignition delay time. The results showed that the addition of GO promoted more heat releases and higher activation energies of Al/Bi2O3/GO CEFs. The addition of ≤3.5 wt. % GO prolonged the ignition duration from 450 μs to 950 μs and increased the maximum height of the ignition product from about 40 mm to 60 mm. However, the micro-ignitors with more than 3.5 wt. % GO cannot be ignited, which suggested that GO played a contradictory role in the ignition properties of micro-ignitors and the controlled GO content was a prerequisite for improved ignition performance. The ignition delay time gradually extended from 10.7 μs to 27.6 μs with increases in the GO contents of Al/Bi2O3 CEFs, revealing that an increase in the weight ratio of GO leads to lower ignition sensitivity of micro-ignitors.

Scale-dependent controls on the area burned in the boreal forest of Canada, 1980-2005

Treesearch

Marc-Andre Parisien; Sean A. Parks; Meg A. Krawchuck; Mike D. Flannigan; Lynn M. Bowman; Max A. Moritz

2011-01-01

In the boreal forest of North America, as in any fire-prone biome, three environmental factors must coincide for a wildfire to occur: an ignition source, flammable vegetation, and weather that is conducive to fire. Despite recent advances, the relative importance of these factors remains the subject of some debate. The aim of this study was to develop models that...

33 CFR 183.440 - Secondary circuits of ignition systems.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Requirements § 183.440 Secondary circuits of ignition systems. (a) Each conductor in a secondary circuit of an ignition system must meet SAE Standard J557. (b) The connection of each ignition conductor to a spark plug...

33 CFR 183.440 - Secondary circuits of ignition systems.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Requirements § 183.440 Secondary circuits of ignition systems. (a) Each conductor in a secondary circuit of an ignition system must meet SAE Standard J557. (b) The connection of each ignition conductor to a spark plug...

Spark ignition of flowing gases I : energies to ignite propane-air mixtures in pressure range of 2 to 4 inches mercury absolute

NASA Technical Reports Server (NTRS)

Swett, Clyde C , Jr

1949-01-01

Ignition studies of flowing gases were made to obtain information applicable to ignition problems in gas-turbine and ram-jet aircraft propulsion systems operating at altitude conditions.Spark energies required for ignition of a flowing propane-air mixture were determined for pressure of 2 to 4 inches mercury absolute, gas velocities of 5.0 to 54.2 feet per second, fuel-air ratios of 0.0607 to 0.1245, and spark durations of 1.5 to 24,400 microseconds. The results showed that at a pressure of 3 inches mercury absolute the minimum energy required for ignition occurred at fuel-air ratios of 0.08 to 0.095. The energy required for ignition increased almost linearly with increasing gas velocity. Shortening the spark duration from approximately 25,000 to 125 microseconds decreased the amount of energy required for ignition. A spark produced by the discharge of a condenser directly into the spark gap and having a duration of 1.5 microseconds required ignition energies larger than most of the long-duration sparks.

Managing the human component of fire regimes: lessons from Africa.

PubMed

Archibald, Sally

2016-06-05

Human impacts on fire regimes accumulated slowly with the evolution of modern humans able to ignite fires and manipulate landscapes. Today, myriad voices aim to influence fire in grassy ecosystems to different ends, and this is complicated by a colonial past focused on suppressing fire and preventing human ignitions. Here, I review available evidence on the impacts of people on various fire characteristics such as the number and size of fires, fire intensity, fire frequency and seasonality of fire in African grassy ecosystems, with the intention of focusing the debate and identifying areas of uncertainty. Humans alter seasonal patterns of fire in grassy systems but tend to decrease total fire emissions: livestock have replaced fire as the dominant consumer in many parts of Africa, and fragmented landscapes reduce area burned. Humans alter the season and time of day when fires occur, with important implications for fire intensity, tree-grass dynamics and greenhouse gas (GHG) emissions. Late season fires are more common when fire is banned or illegal: these later fires are far more intense but emit fewer GHGs. The types of fires which preserve human livelihoods and biodiversity are not always aligned with the goal of reducing GHG concentrations. Current fire management challenges therefore involve balancing the needs of a large rural population against national and global perspectives on the desirability of different types of fire, but this cannot happen unless the interests of all parties are equally represented. In the future, Africa is expected to urbanize and land use to intensify, which will imply different trajectories for the continent's fire regimes.This article is part of the themed issue 'The interaction of fire and mankind. © 2016 The Author(s).

Managing the human component of fire regimes: lessons from Africa

PubMed Central

Archibald, Sally

2016-01-01

Human impacts on fire regimes accumulated slowly with the evolution of modern humans able to ignite fires and manipulate landscapes. Today, myriad voices aim to influence fire in grassy ecosystems to different ends, and this is complicated by a colonial past focused on suppressing fire and preventing human ignitions. Here, I review available evidence on the impacts of people on various fire characteristics such as the number and size of fires, fire intensity, fire frequency and seasonality of fire in African grassy ecosystems, with the intention of focusing the debate and identifying areas of uncertainty. Humans alter seasonal patterns of fire in grassy systems but tend to decrease total fire emissions: livestock have replaced fire as the dominant consumer in many parts of Africa, and fragmented landscapes reduce area burned. Humans alter the season and time of day when fires occur, with important implications for fire intensity, tree–grass dynamics and greenhouse gas (GHG) emissions. Late season fires are more common when fire is banned or illegal: these later fires are far more intense but emit fewer GHGs. The types of fires which preserve human livelihoods and biodiversity are not always aligned with the goal of reducing GHG concentrations. Current fire management challenges therefore involve balancing the needs of a large rural population against national and global perspectives on the desirability of different types of fire, but this cannot happen unless the interests of all parties are equally represented. In the future, Africa is expected to urbanize and land use to intensify, which will imply different trajectories for the continent's fire regimes. This article is part of the themed issue ‘The interaction of fire and mankind. PMID:27216516

Effects of season on ignition of live wildland fuels using the forced ignition and flame spread test apparatus

Treesearch

S. McAllister; D. R. Weise

2017-01-01

An understanding of what variables affect the ignition of live wildland fuels is crucial to predicting crown fire spread, the most poorly understood type of wildland fire. Ignition tests were performed over the course of an entire year for ten species (three species in year one, seven in year two) to evaluate seasonal changes in flammability. Ignition delay and mass...

Remote fire stack igniter. [with solenoid-controlled valve

NASA Technical Reports Server (NTRS)

Ray, W. L. (Inventor)

1974-01-01

An igniter is described mounted on a vent stack with an upper, flame cage near the top of the stack to ignite emissions from the stack. The igniter is a tube with a lower, open, flared end having a spark plug near the lower end and a solenoid-controlled valve which supplies propane fuel from a supply tank. Propane from the tank is supplied at the top under control of a second, solenoid-controlled valve. The valve controlling the lower supply is closed after ignition at the flame cage. The igniter is economical, practical, and highly reliable.

Space-time modelling of lightning-caused ignitions in the Blue Mountains, Oregon

USGS Publications Warehouse

Diaz-Avalos, Carlos; Peterson, D.L.; Alvarado, Ernesto; Ferguson, Sue A.; Besag, Julian E.

2001-01-01

Generalized linear mixed models (GLMM) were used to study the effect of vegetation cover, elevation, slope, and precipitation on the probability of ignition in the Blue Mountains, Oregon, and to estimate the probability of ignition occurrence at different locations in space and in time. Data on starting location of lightning-caused ignitions in the Blue Mountains between April 1986 and September 1993 constituted the base for the analysis. The study area was divided into a pixela??time array. For each pixela??time location we associated a value of 1 if at least one ignition occurred and 0 otherwise. Covariate information for each pixel was obtained using a geographic information system. The GLMMs were fitted in a Bayesian framework. Higher ignition probabilities were associated with the following cover types: subalpine herbaceous, alpine tundra, lodgepole pine (Pinus contorta Dougl. ex Loud.), whitebark pine (Pinus albicaulis Engelm.), Engelmann spruce (Picea engelmannii Parry ex Engelm.), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), and grand fir (Abies grandis (Dougl.) Lindl.). Within each vegetation type, higher ignition probabilities occurred at lower elevations. Additionally, ignition probabilities are lower in the northern and southern extremes of the Blue Mountains. The GLMM procedure used here is suitable for analysing ignition occurrence in other forested regions where probabilities of ignition are highly variable because of a spatially complex biophysical environment.

Forest fires and lightning activity during the outstanding 2003 and 2005 fire seasons

NASA Astrophysics Data System (ADS)

Russo, Ana; Ramos, Alexandre; Trigo, Ricardo

2013-04-01

Wildfires in southern Europe cause frequent extensive economical and ecological losses and, even human casualties. Comparatively to other Mediterranean countries, Portugal is the country with more burnt area and fires per unit area in the last decade, mainly during the summer season (Pereira et al., 2011). According to the fire records available, between 1980 and 2009, wildfires have affected over 3 million hectares in Portugal (JRC, 2011), which corresponds to approximately a third of the Portuguese Continental territory. The main factors that influence fire ignition and propagation are: (1) the presence of fuel (i.e. vegetation); (2) climate and weather; (3) socioeconomic conditions that affect land use/land cover patterns, fire-prevention and fire-fighting capacity and (4) topography. Specifically, weather (e.g. wind, temperature, precipitation, humidity, and lightning occurrence) plays an important role in fire behavior, affecting both ignition and spread of wildfires. Some countries have a relatively large fraction of fires caused by lightning, e.g. northwestern USA, Canada, Russia (). In contrast, Portugal has only a small percentage of fire records caused by lightning. Although significant doubts remain for the majority of fires in the catalog since they were cataloged without a likely cause. The recent years of 2003 and 2005 were particularly outstanding for fire activity in Portugal, registering, respectively, total burned areas of 425 726 ha and 338 262 ha. However, while the 2003 was triggered by an exceptional heatwave that struck the entire western Europe, the 2005 fire season registered was coincident with one of the most severe droughts of the 20th century. In this work we have used mainly two different databases: 1) the Portuguese Rural Fire Database (PRFD) which is representative of rural fires that have occurred in Continental Portugal, 2001-2011, with the original data provided by the Autoridade Florestal Nacional (AFN, 2011); 2) lightning discharges location which were extracted from the Portuguese Lightning Location System that has been in service since June of 2002 and is operated by the national weather service - Instituto de Meteorologia (IM). The main objective of this work is to analyze for possible relations between the PRFD and the Portuguese lightning database for the 2003 and 2005 extreme fire seasons. In particularly we were able to verify the forest fires labeled as "ignited by lightning" by comparing its location to the lightning discharges location database. Furthermore we have also investigated possible fire ignition by lightning discharges that have not yet been labeled in the PRFD by comparing daily data from both datasets.

One pediatric burn unit's experience with sleepwear related injuries

PubMed Central

McLoughlin, E.; Clarke, N.; Stahl, K.; Crawford, J.

1998-01-01

Review of the records of 678 children with acute injuries referred during an eight year period to this burn unit indicated that flame burns from a single ignition source (50%) outranked scalds (27%) or house fires (12%) as causes of injury. There was no temporal trend in the rank pattern. The majority of these single-source flame injuries were severe and involved ignition of the child's clothing. From 1969 through 1973, sleepwear was the clothing involved in 32% of the instances. Since that time and coincident with promulgation of strict federal and state standards for flammability of children's night clothing, a dramatic decline in the number of children referred with injuries of this type has taken place. It is probable that the single factor most important to the decline, in our experience with these injuries, is lower fabric flammability but, because our data may not be representative, corroboration is needed before one can exclude factors such as altered garment design, fire safety related practices at home, or changing patterns of hospital referral. PMID:9887427

Analyzing seasonal patterns of wildfire exposure factors in Sardinia, Italy.

PubMed

Salis, Michele; Ager, Alan A; Alcasena, Fermin J; Arca, Bachisio; Finney, Mark A; Pellizzaro, Grazia; Spano, Donatella

2015-01-01

In this paper, we applied landscape scale wildfire simulation modeling to explore the spatiotemporal patterns of wildfire likelihood and intensity in the island of Sardinia (Italy). We also performed wildfire exposure analysis for selected highly valued resources on the island to identify areas characterized by high risk. We observed substantial variation in burn probability, fire size, and flame length among time periods within the fire season, which starts in early June and ends in late September. Peak burn probability and flame length were observed in late July. We found that patterns of wildfire likelihood and intensity were mainly related to spatiotemporal variation in ignition locations, fuel moisture, and wind vectors. Our modeling approach allowed consideration of historical patterns of winds, ignition locations, and live and dead fuel moisture on fire exposure factors. The methodology proposed can be useful for analyzing potential wildfire risk and effects at landscape scale, evaluating historical changes and future trends in wildfire exposure, as well as for addressing and informing fuel management and risk mitigation issues.

Ignition of Combustible Dust Clouds by Strong Capacitive Electric Sparks of Short Discharge Times

NASA Astrophysics Data System (ADS)

Eckhoff, Rolf K.

2017-10-01

It has been known for more than half a century that the discharge times of capacitive electric sparks can influence the minimum ignition energies of dust clouds substantially. Experiments by various workers have shown that net electric-spark energies for igniting explosive dust clouds in air were reduced by a factor of the order of 100 when spark discharge times were increased from a few μs to 0.1-1 ms. Experiments have also shown that the disturbance of the dust cloud by the shock/blast wave emitted by "short" spark discharges is a likely reason for this. The disturbance increases with increasing spark energy. In this paper a hitherto unpublished comprehensive study of this problem is presented. The work was performed about 50 years ago, using sparks of comparatively high energies (strong sparks). Lycopodium was used as test dust. The experiments were conducted in a brass vessel of 1 L volume. A transient dust cloud was generated in the vessel by a blast of compressed air. Synchronization of appearance of dust cloud and spark discharge was obtained by breaking the spark gap down by the dust cloud itself. This may in fact also be one possible synchronization mechanism in accidental industrial dust explosions initiated by electrostatic sparks. The experimental results for various spark energies were expressed as the probability of ignition, based on 100 replicate experiments, as a function of the nominal dust concentration. All probabilities obtained were 0%

Capsule Performance Optimization in the National Ignition Campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landen, O L; MacGowan, B J; Haan, S W

2009-10-13

A capsule performance optimization campaign will be conducted at the National Ignition Facility to substantially increase the probability of ignition. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting themore » key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.« less

Capsule performance optimization in the national ignition campaign

NASA Astrophysics Data System (ADS)

Landen, O. L.; MacGowan, B. J.; Haan, S. W.; Edwards, J.

2010-08-01

A capsule performance optimization campaign will be conducted at the National Ignition Facility [1] to substantially increase the probability of ignition. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

Laser ignition of a multi-injector LOX/methane combustor

NASA Astrophysics Data System (ADS)

Börner, Michael; Manfletti, Chiara; Hardi, Justin; Suslov, Dmitry; Kroupa, Gerhard; Oschwald, Michael

2018-06-01

This paper reports the results of a test campaign of a laser-ignited combustion chamber with 15 shear coaxial injectors for the propellant combination LOX/methane. 259 ignition tests were performed for sea-level conditions. The igniter based on a monolithic ceramic laser system was directly attached to the combustion chamber and delivered 20 pulses with individual pulse energies of {33.2 ± 0.8 mJ } at 1064 nm wavelength and 2.3 ns FWHM pulse length. The applicability, reliability, and reusability of this ignition technology are demonstrated and the associated challenges during the start-up process induced by the oxygen two-phase flow are formulated. The ignition quality and pressure dynamics are evaluated using 14 dynamic pressure sensors distributed both azimuthally and axially along the combustion chamber wall. The influence of test sequencing on the ignition process is briefly discussed and the relevance of the injection timing of the propellants for the ignition process is described. The flame anchoring and stabilization process, as monitored using an optical probe system close to the injector faceplate connected to photomultiplier elements, is presented. For some of the ignition tests, non-uniform anchoring was detected with no influence onto the anchoring at steady-state conditions. The non-uniform anchoring can be explained by the inhomogeneous, transient injection of the two-phase flow of oxygen across the faceplate. This characteristic is verified by liquid nitrogen cold flow tests that were recorded by high-speed imaging. We conclude that by adapting the ignition sequence, laser ignition by optical breakdown of the propellants within the shear layer of a coaxial shear injector is a reliable ignition technology for LOX/methane combustors without significant over-pressure levels.

Laser ignition of a multi-injector LOX/methane combustor

NASA Astrophysics Data System (ADS)

Börner, Michael; Manfletti, Chiara; Hardi, Justin; Suslov, Dmitry; Kroupa, Gerhard; Oschwald, Michael

2018-02-01

This paper reports the results of a test campaign of a laser-ignited combustion chamber with 15 shear coaxial injectors for the propellant combination LOX/methane. 259 ignition tests were performed for sea-level conditions. The igniter based on a monolithic ceramic laser system was directly attached to the combustion chamber and delivered 20 pulses with individual pulse energies of {33.2 ± 0.8 mJ } at 1064 nm wavelength and 2.3 ns FWHM pulse length. The applicability, reliability, and reusability of this ignition technology are demonstrated and the associated challenges during the start-up process induced by the oxygen two-phase flow are formulated. The ignition quality and pressure dynamics are evaluated using 14 dynamic pressure sensors distributed both azimuthally and axially along the combustion chamber wall. The influence of test sequencing on the ignition process is briefly discussed and the relevance of the injection timing of the propellants for the ignition process is described. The flame anchoring and stabilization process, as monitored using an optical probe system close to the injector faceplate connected to photomultiplier elements, is presented. For some of the ignition tests, non-uniform anchoring was detected with no influence onto the anchoring at steady-state conditions. The non-uniform anchoring can be explained by the inhomogeneous, transient injection of the two-phase flow of oxygen across the faceplate. This characteristic is verified by liquid nitrogen cold flow tests that were recorded by high-speed imaging. We conclude that by adapting the ignition sequence, laser ignition by optical breakdown of the propellants within the shear layer of a coaxial shear injector is a reliable ignition technology for LOX/methane combustors without significant over-pressure levels.

Theoretical and Experimental Investigations of Ignition, Combustion and Expansion Processes of Hypergolic Liquid Fuel Combinations at Gas Temperatures up to 3000 K. Thesis - Rhein-Westfalia Technical Coll., 1967

NASA Technical Reports Server (NTRS)

Schulz, Harry

1987-01-01

The ignition, combustion, and expansion characteristics of hypergolic liquid propellant mixtures in small rocket engines are studied theoretically and experimentally. It is shown by using the Bray approximation procedure that the reaction H + OH + M = H2O + M (where M is the molecular mass of the gas mixture) has a strong effect on the combustion efficiency. Increases in recombination energies ranging from 30 to 65% were obtained when the rate of this reaction was increased by a factor of 10 in gas mixtures containing 90% oxygen. The effect of aluminum additions and various injection techniques on the combustion process is investigated.

First Iron Opacity Experiments on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Perry, Theodore; Dodd, Evan; Cardenas, Tana; Devolder, Barbara; Flippo, Kirk; Johns, Heather; Kline, John; Sherrill, Manolo; Urbatsch, Todd; Heeter, Robert; Ahmed, Maryum; Emig, James; Iglesias, Carlos; Liedahl, Duane; London, Richard; Martin, Madison; Schneider, Marilyn; Thompson, Nathaniel; Wilson, Brian; Opachich, Yekaterina; King, James; Huffman, Eric; Knight, Russel; Bailey, James; Rochau, Gregory

2017-10-01

Iron opacity experiments on the Sandia National Laboratories Z machine have shown up to factors of two discrepancies between theory and experiment. To help resolve these discrepancies an experimental platform for doing comparable opacity experiments is being developed on the National Ignition Facility (NIF). Initial iron data has been taken at a temperature of 150 eV and an electron density of 6x1021/cm3, but higher temperatures and densities will be required to address the discrepancies that have been observed in the Z experiments. The plans to go to higher temperatures and densities and how to deal with current issues with instrumental backgrounds will be discussed. Performed under the auspices of USDOE LANL Contract DE-AC52-06NA25396.

Self-ignition of S.I. engine model fuels: A shock tube investigation at high pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fieweger, K.; Blumenthal, R.; Adomeit, G.

1997-06-01

The self-ignition of several spark-ignition (SI) engine fuels (iso-octane, methanol, methyl tert-butyl ether and three different mixtures of iso-octane and n-heptane), mixed with air, was investigated experimentally under relevant engine conditions by the shock tube technique. Typical modes of the self-ignition process were registered cinematographically. For temperatures relevant to piston engine combustion, the self-ignition process always starts as an inhomogeneous, deflagrative mild ignition. This instant is defined by the ignition delay time, {tau}{sub defl}. The deflagration process in most cases is followed by a secondary explosion (DDT). This transition defines a second ignition delay time, {tau}{sub DDT}, which is amore » suitable approximation for the chemical ignition delay time, if the change of the thermodynamic conditions of the unburned test gas due to deflagration is taken into account. For iso-octane at p = 40 bar, a NTC (negative temperature coefficient), behavior connected with a two step (cool flame) self-ignition at low temperatures was observed. This process was very pronounced for rich and less pronounced for stoichiometric mixtures. The results of the {tau}{sub DDT} delays of the stoichiometric mixtures were shortened by the primary deflagration process in the temperature range between 800 and 1,000 K. Various mixtures of iso-octane and n-heptane were investigated. The results show a strong influence of the n-heptane fraction in the mixture, both on the ignition delay time and on the mode of self-ignition. The self-ignition of methanol and MTBE (methyl tert-butyl ether) is characterized by a very pronounced initial deflagration. For temperatures below 900 K (methanol: 800 K), no secondary explosion occurs. Taking into account the pressure increase due to deflagration, the measured delays {tau}{sub DDT} of the secondary explosion are shortened by up to one order of magnitude.« less

National Ignition Facility under fire over ignition failure

NASA Astrophysics Data System (ADS)

Allen, Michael

2016-08-01

The 3.5bn National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in California is no nearer to igniting a sustainable nuclear fusion burn - four years after its initial target date - according to a report by the US National Nuclear Security Administration (NNSA).

A Comparison of Several Methods of Measuring Ignition Lag in a Compression-ignition Engine

NASA Technical Reports Server (NTRS)

Spanogle, J A

1934-01-01

The ignition lag of a fuel oil in the combustion chamber of a high speed compression-ignition engine was measured by three different methods. The start of injection of the fuel as observed with a Stoborama was taken as the start of the period of ignition lag in all cases. The end of the period of ignition lag was determined by observation of the appearance of incandescence in the combustion chamber, by inspection of a pressure-time card for evidence of pressure rise, and by analysis of the indicator card for evidence of the combustion of a small but definite quantity of fuel. A comparison of the values for ignition lags obtained by these three methods indicates that the appearance of incandescence is later than other evidences of the start of combustion, that visual inspection of a pressure-time diagram gives consistent and usable values with a minimum requirement of time and/or apparatus, and that analysis of the indicator card is not worth while for ignition lag alone.

Irradiated ignition of solid materials in reduced pressure atmosphere with various oxygen concentrations for fire safety in space habitats

NASA Astrophysics Data System (ADS)

Nakamura, Y.; Aoki, A.

Effects of sub-atmospheric ambient pressure and oxygen content on irradiated ignition characteristics of solid combustibles were examined experimentally in order to elucidate the flammability and chance of fire in depressurized systems and give ideas for the fire safety and fire fighting strategies for such environments. Thin cellulosic paper was used as the solid combustible since cellulose is one of major organic compounds and flammables in the nature. Applied atmospheres consisted of inert gases (either CO 2 or N 2) and oxygen at various mixture ratios. Total ambient pressure ( P) was varied from 101 kPa (standard atmospheric pressure, P0) to 20 kPa. Ignition was initiated by external thermal radiation with CO 2 laser (10 W total; 21.3 W/cm 2 of the corresponding peak flux) onto the solid surface. Thermal degradation of the solid produced combustible gaseous products (e.g. CO, H 2, or other low weight of HCs) and these products mixed with ambient oxygen to form the combustible mixture over the solid. Heat transfer from the irradiated surface into the mixture accelerated the exothermic reaction in the gas phase and finally thermal runaway (ignition) was achieved. A digital video camera was used to analyze the ignition characteristics. Flammability maps in partial pressure of oxygen (ppO 2) and normalized ambient pressure ( P/ P0) plane were made to reveal the fire hazard in depressurized environments. Results showed that a wider flammable range was obtained in sub-atmospherics conditions. In middle pressure range (101-40 kPa), the required ppO 2 for ignition decreased almost linearly as the total pressure decreased, indicating that higher fire risk is expected. In lower pressure range (<40 kPa), the required partial pressure of oxygen increased dramatically, then ignition was eventually not achieved at pressures less than 20 kPa under the conditions studied here. The findings suggest that it might be difficult to satisfy safety in space agriculture since it has been reported that higher oxygen concentrations are preferable for plant growth in depressurized environments. Our results imply that there is an optimum pressure level to achieve less fire chance with acceptable plant growth. An increase of the flammable range in middle pressure level might be explained by following two effects: one is a physical effect, such as a weak convective thermal removal from ignitable domain (near the hot surface) to the ambient of atmosphere, and the other is chemical effect which causes so-called "explosion peninsula" as a result of depleting radical consumption due to third-body recombination reaction. Further studies are necessary to determine the controlling factor on the observed flammable trend in depressurized conditions.

The Spiritual Dimension of Leadership: How Leaders Ignite the Spirit of the Community College

ERIC Educational Resources Information Center

Myran, Gunder; Myran, Steven; Galant, Richard

2004-01-01

Community college leaders commonly think of community college leadership in terms of rationality, expertise, power, negotiations, and legalisms rather than the more human, loving, symbolic, and transcendent dimensions of their work. Yet the giving of oneself to a common cause, to a higher calling, is the most important role community college…

We still need Smokey Bear!

USGS Publications Warehouse

Keeley, Jon E.

2001-01-01

It was gratifying to see articles in recent issues of Fire Management Today clarifying the role of Smokey Bear in wildland fire management strategies (Baily 1999; Brown 1999). These articles clearly spelled out Smokey’s importance in reducing unplanned human-ignited wildland fires and rightly criticized attempts to detract from Smokey’s campaign (Williams 1995; see also Vogl 1973).

Re-examining the effect of low and intermediate mode number perturbations on Ignition Metrics Scaling Laws

NASA Astrophysics Data System (ADS)

Malka, Elad; Shvarts, Dov

2017-10-01

We re-examine the way 2/3D effects on scaling laws for ignition metrics, such as the generalized Lawson Criterion (GLC) and the Ignition Threshold Factor (ITF). These scaling laws were derived for 1D symmetrical case and 2/3D perturbations [Hann et al. PoP 2010; Lindl et al., PoP 2014; Betti et al., PoP 2010]. The main cause for the difference between the 1D and the 2/3D scaling laws in those works, is heat conduction losses from the hot-spot bubbles to the cold shell [Kishony and Shvarts, PoP 2001]. This ``dry out'' of the bubbles is the dominant mechanism for intermediate mode number perturbations (6

Impacts of Implosion Asymmetry And Hot Spot Shape On Ignition Capsules

NASA Astrophysics Data System (ADS)

Cheng, Baolian; Kwan, Thomas J. T.; Wang, Yi-Ming; Yi, S. Austin; Batha, Steve

2017-10-01

Implosion symmetry plays a critical role in achieving high areal density and internal energy at stagnation during hot spot formation in ICF capsules. Asymmetry causes hot spot irregularity and stagnation de-synchronization that results in lower temperatures and areal densities of the hot fuel. These degradations significantly affect the alpha heating process in the DT fuel as well as on the thermonuclear performance of the capsules. In this work, we explore the physical factors determining the shape of the hot spot late in the implosion and the effects of shape on Î+/-particle transport. We extend our ignition theory [1-4] to include the hot spot shape and quantify the effects of the implosion asymmetry on both the ignition criterion and capsule performance. We validate our theory with the NIF existing experimental data Our theory shows that the ignition criterion becomes more restrictive with the deformation of the hot spot. Through comparison with the NIF data, we demonstrate that the shape effects on the capsules' performance become more explicit as the self-heating and yield of the capsules increases. The degradation of the thermonuclear burn by the hot spot shape for high yield shots to date can be as high as 20%. Our theory is in good agreement with the NIF data. This work was performed under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under Contract No. W-7405-ENG-36.

Combustion characteristics and influential factors of isooctane active-thermal atmosphere combustion assisted by two-stage reaction of n-heptane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Xingcai; Ji, Libin; Ma, Junjun

2011-02-15

This paper presents an experimental study on the isooctane active-thermal atmosphere combustion (ATAC) which is assisted by two-stage reaction of n-heptane. The active-thermal atmosphere is created by low- and high-temperature reactions of n-heptane which is injected at intake port, and isooctane is directly injected into combustion chamber near the top dead center. The effects of isooctane injection timing, active-thermal atmosphere intensity, overall equivalence ratio, and premixed ratio on combustion characteristics and emissions are investigated. The experimental results reveal that, the isooctane ignition and combustion can be classified to thermal atmosphere combustion, active atmosphere combustion, and active-thermal atmosphere combustion respectively accordingmore » to the extent of n-heptane oxidation as well as effects of isooctane quenching and charge cooling. n-Heptane equivalence ratio, isooctane equivalence ratio and isooctane delivery advance angle are major control parameters. In one combustion cycle, the isooctane ignited and burned after those of n-heptane, and then this combustion phenomenon can also be named as dual-fuel sequential combustion (DFSC). The ignition timing of the overall combustion event is mainly determined by n-heptane equivalence ratio and can be controlled in flexibility by simultaneously adjusting isooctane equivalence ratio. The isooctane ignition regime, overall thermal efficiency, and NO{sub x} emissions show strong sensitivity to the fuel delivery advance angle between 20 CA BTDC and 25 CA BTDC. (author)« less

Ignition and Performance Tests of Rocket-Based Combined Cycle Propulsion System

NASA Technical Reports Server (NTRS)

Anderson, William E.

2005-01-01

The ground testing of a Rocket Based Combined Cycle engine implementing the Simultaneous Mixing and Combustion scheme was performed at the direct-connect facility of Purdue University's High Pressure Laboratory. The fuel-rich exhaust of a JP-8/H2O2 thruster was mixed with compressed, metered air in a constant area, axisymmetric duct. The thruster was similar in design and function to that which will be used in the flight test series of Dryden's Ducted-Rocket Experiment. The determination of duct ignition limits was made based on the variation of secondary air flow rates and primary thruster equivalence ratios. Thrust augmentation and improvements in specific impulse were studied along with the pressure and temperature profiles of the duct to study mixing lengths and thermal choking. The occurrence of ignition was favored by lower rocket equivalence ratios. However, among ignition cases, better thrust and specific impulse performance were seen with higher equivalence ratios owing to the increased fuel available for combustion. Thrust and specific impulse improvements by factors of 1.2 to 1.7 were seen. The static pressure and temperature profiles allowed regions of mixing and heat addition to be identified. The mixing lengths were found to be shorter at lower rocket equivalence ratios. Total pressure measurements allowed plume-based calculation of thrust, which agreed with load-cell measured values to within 6.5-8.0%. The corresponding Mach Number profile indicated the flow was not thermally choked for the highest duct static pressure case.

Two-Dimensional Simulations of Electron Shock Ignition at the Megajoule Scale

NASA Astrophysics Data System (ADS)

Shang, W.; Betti, R.

2016-10-01

Shock ignition uses a late strong shock to ignite the hot spot of an inertial confinement fusion capsule. In the standard shock-ignition scheme, an ignitor shock is launched by the ablation pressure from a spike in laser intensity. Recent experiments on OMEGA have shown that focused beams with intensity up to 6 ×1015 W /cm2 can produce copious amounts of hot electrons. The hot electrons are produced by laser-plasma instabilities (LPI's) and can carry up to 15 % of the instantaneous laser power. Megajoule-scale targets will likely produce even more hot electrons because of the large plasma scale length. We show that it is possible to design ignition targets with low implosion velocities that can be shock ignited using LPI-generated hot electrons to obtain high energy gains. These designs are robust to low-mode asymmetries and they ignite even for highly distorted implosions. Electron shock ignition requires tens of kilojoules of hot electrons, which can only be produced on a large laser facility like the National Ignition Facility. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

The impact of physicochemical property interactions of iso -octane/ethanol blends on ignition timescales

DOE PAGES

Barraza-Botet, Cesar L.; Luecke, Jon; Zigler, Bradley T.; ...

2018-03-20

This work presents new measurements of liquid fuel ignition delay times of iso-octane and ethanol fuel blends obtained from an ignition quality tester at the National Renewable Energy Laboratory (NREL IQT), which are compared to previous ignition delay data from the University of Michigan rapid compression facility (UM RCF), at the same experimental conditions. Pressure-time histories were used to determine liquid fuel ignition delays at global stoichiometric non-premixed conditions for iso-octane, ethanol and iso-octane/ethanol blends of 25, 50, 75% by volume in mixtures of 10% oxygen diluted in nitrogen. Temperatures ranging from 880 to 970 K were studied at amore » pressure of 10 atm. By comparing total ignition delay times from the NREL IQT with chemical ignition delay times from the UM RCF, the contributions of physical phenomena were quantified as representative time scales for spray injection, breakup and evaporation processes, and for gas-phase turbulent mixing. Regression analyses were developed for ignition time scales as function of blend level and charge temperature. Non-dimensional analyses were also carried out to determine the relative effects of physical time scales with respect to chemical ignition delay times.« less

Simulations of electron transport and ignition for direct-drive fast-ignition targets

NASA Astrophysics Data System (ADS)

Solodov, A. A.; Anderson, K. S.; Betti, R.; Gotcheva, V.; Myatt, J.; Delettrez, J. A.; Skupsky, S.; Theobald, W.; Stoeckl, C.

2008-11-01

The performance of high-gain, fast-ignition fusion targets is investigated using one-dimensional hydrodynamic simulations of implosion and two-dimensional (2D) hybrid fluid-particle simulations of hot-electron transport, ignition, and burn. The 2D/3D hybrid-particle-in-cell code LSP [D. R. Welch et al., Nucl. Instrum. Methods Phys. Res. A 464, 134 (2001)] and the 2D fluid code DRACO [P. B. Radha et al., Phys. Plasmas 12, 056307 (2005)] are integrated to simulate the hot-electron transport and heating for direct-drive fast-ignition targets. LSP simulates the transport of hot electrons from the place where they are generated to the dense fuel core where their energy is absorbed. DRACO includes the physics required to simulate compression, ignition, and burn of fast-ignition targets. The self-generated resistive magnetic field is found to collimate the hot-electron beam, increase the coupling efficiency of hot electrons with the target, and reduce the minimum energy required for ignition. Resistive filamentation of the hot-electron beam is also observed. The minimum energy required for ignition is found for hot electrons with realistic angular spread and Maxwellian energy-distribution function.

The impact of physicochemical property interactions of iso -octane/ethanol blends on ignition timescales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barraza-Botet, Cesar L.; Luecke, Jon; Zigler, Bradley T.

This work presents new measurements of liquid fuel ignition delay times of iso-octane and ethanol fuel blends obtained from an ignition quality tester at the National Renewable Energy Laboratory (NREL IQT), which are compared to previous ignition delay data from the University of Michigan rapid compression facility (UM RCF), at the same experimental conditions. Pressure-time histories were used to determine liquid fuel ignition delays at global stoichiometric non-premixed conditions for iso-octane, ethanol and iso-octane/ethanol blends of 25, 50, 75% by volume in mixtures of 10% oxygen diluted in nitrogen. Temperatures ranging from 880 to 970 K were studied at amore » pressure of 10 atm. By comparing total ignition delay times from the NREL IQT with chemical ignition delay times from the UM RCF, the contributions of physical phenomena were quantified as representative time scales for spray injection, breakup and evaporation processes, and for gas-phase turbulent mixing. Regression analyses were developed for ignition time scales as function of blend level and charge temperature. Non-dimensional analyses were also carried out to determine the relative effects of physical time scales with respect to chemical ignition delay times.« less

Plasma Igniter for Reliable Ignition of Combustion in Rocket Engines

NASA Technical Reports Server (NTRS)

Martin, Adam; Eskridge, Richard

2011-01-01

A plasma igniter has been developed for initiating combustion in liquid-propellant rocket engines. The device propels a hot, dense plasma jet, consisting of elemental fluorine and fluorine compounds, into the combustion chamber to ignite the cold propellant mixture. The igniter consists of two coaxial, cylindrical electrodes with a cylindrical bar of solid Teflon plastic in the region between them. The outer electrode is a metal (stainless steel) tube; the inner electrode is a metal pin (mild steel, stainless steel, tungsten, or thoriated-tungsten). The Teflon bar fits snugly between the two electrodes and provides electrical insulation between them. The Teflon bar may have either a flat surface, or a concave, conical surface at the open, down-stream end of the igniter (the igniter face). The igniter would be mounted on the combustion chamber of the rocket engine, either on the injector-plate at the upstream side of the engine, or on the sidewalls of the chamber. It also might sit behind a valve that would be opened just prior to ignition, and closed just after, in order to prevent the Teflon from melting due to heating from the combustion chamber.

Physical characteristics of welding arc ignition process

NASA Astrophysics Data System (ADS)

Shi, Linan; Song, Yonglun; Xiao, Tianjiao; Ran, Guowei

2012-07-01

The existing research of welding arc mainly focuses on the stable combustion state and the research on the mechanism of welding arc ignition process is quite lack. The tungsten inert gas(TIG) touch arc ignition process is observed via a high speed camera and the high time resolution spectral diagnosis system. The changing phenomenon of main ionized element provided the electrons in the arc ignition is found. The metallic element is the main contributor to provide the electrons at the beginning of the discharging, and then the excitated shielding gas element replaces the function of the metallic element. The electron density during the period of the arc ignition is calculated by the Stark-broadened lines of Hα. Through the discussion with the repeatability in relaxation phenomenon, the statistical regularity in the arc ignition process is analyzed. The similar rules as above are observed through the comparison with the laser-assisted arc ignition experiments and the metal inert gas(MIG) arc ignition experiments. This research is helpful to further understanding on the generation mechanism of welding arc ignition and also has a certain academic and practical significance on enriching the welding physical theoretical foundation and improving the precise monitoring on automatic arc welding process.

Evaluation and Characterization Study of Dual Pulse Laser-Induced Spark (DPLIS) for Rocket Engine Ignition System Application

NASA Technical Reports Server (NTRS)

Osborne, Robin; Wehrmeyer, Joseph; Trinh, Huu; Early, James

2003-01-01

This paper addresses the progress of technology development of a laser ignition system at NASA Marshall Space Flight Center (MSFC). Laser ignition has been used at MSFC in recent test series to successfully ignite RP1/GOX propellants in a subscale rocket chamber, and other past studies by NASA GRC have demonstrated the use of laser ignition for rocket engines. Despite the progress made in the study of this ignition method, the logistics of depositing laser sparks inside a rocket chamber have prohibited its use. However, recent advances in laser designs, the use of fiber optics, and studies of multi-pulse laser formats3 have renewed the interest of rocket designers in this state-of the-art technology which offers the potential elimination of torch igniter systems and their associated mechanical parts, as well as toxic hypergolic ignition systems. In support of this interest to develop an alternative ignition system that meets the risk-reduction demands of Next Generation Launch Technology (NGLT), characterization studies of a dual pulse laser format for laser-induced spark ignition are underway at MSFC. Results obtained at MSFC indicate that a dual pulse format can produce plasmas that absorb the laser energy as efficiently as a single pulse format, yet provide a longer plasma lifetime. In an experiments with lean H2/air propellants, the dual pulse laser format, containing the same total energy of a single laser pulse, produced a spark that was superior in its ability to provide sustained ignition of fuel-lean H2/air propellants. The results from these experiments are being used to optimize a dual pulse laser format for future subscale rocket chamber tests. Besides the ignition enhancement, the dual pulse technique provides a practical way to distribute and deliver laser light to the combustion chamber, an important consideration given the limitation of peak power that can be delivered through optical fibers. With this knowledge, scientists and engineers at Los Alamos National Laboratory and CFD Research Corporation have designed and fabricated a miniaturized, first-generation optical prototype of a laser ignition system that could be the basis for a laser ignition system for rocket applications. This prototype will be tested at MSFC in future subscale rocket ignition tests.

Laser Ignition Technology for Bi-Propellant Rocket Engine Applications

NASA Technical Reports Server (NTRS)

Thomas, Matt; Bossard, John; Early, Jim; Trinh, Huu; Dennis, Jay; Turner, James (Technical Monitor)

2001-01-01

This viewgraph presentation gives an overview of laser ignition technology for bipropellant rocket engines applications. The objectives of this project include: (1) the selection test chambers and flows; (2) definition of the laser ignition setup; (3) pulse format optimization; (4) fiber optic coupled laser ignition system analysis; and (5) chamber integration issues definition. The testing concludes that rocket combustion chamber laser ignition is imminent. Support technologies (multiplexing, window durability/cleaning, and fiber optic durability) are feasible.

A Home Ignition Assessment Model Applied to Structures in the Wildland-Urban Interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biswas, Kaushik; Werth, David; Gupta, Narendra

2013-01-01

The issue of exterior fire threat to buildings, from either wildfires in the wildland-urban interface or neighboring structure fires, is critically important. To address this, theWildfire Ignition Resistant Home Design (WIRHD) program was initiated. The WIRHD program developed a tool, theWildFIREWizard, that will allow homeowners to estimate the external fire threat to their homes based on specific features and characteristics of the homes and yards. The software then makes recommendations to reduce the threat. The inputs include the structural and material features of the home and information about any ignition sources or flammable objects in its immediate vicinity, known asmore » the home ignition zone. The tool comprises an ignition assessment model that performs explicit calculations of the radiant and convective heating of the building envelope from the potential ignition sources. This article describes a series of material ignition and flammability tests that were performed to calibrate and/or validate the ignition assessment model. The tests involved exposing test walls with different external siding types to radiant heating and/or direct flame contact.The responses of the test walls were used to determine the conditions leading to melting, ignition, or any other mode of failure of the walls. Temperature data were used to verify the model predictions of temperature rises and ignition times of the test walls.« less

Laser Ignition Microthruster Experiments on KKS-1

NASA Astrophysics Data System (ADS)

Nakano, Masakatsu; Koizumi, Hiroyuki; Watanabe, Masashi; Arakawa, Yoshihiro

A laser ignition microthruster has been developed for microsatellites. Thruster performances such as impulse and ignition probability were measured, using boron potassium nitrate (B/KNO3) solid propellant ignited by a 1 W CW laser diode. The measured impulses were 60 mNs ± 15 mNs with almost 100 % ignition probability. The effect of the mixture ratios of B/KNO3 on thruster performance was also investigated, and it was shown that mixture ratios between B/KNO3/binder = 28/70/2 and 38/60/2 exhibited both high ignition probability and high impulse. Laser ignition thrusters designed and fabricated based on these data became the first non-conventional microthrusters on the Kouku Kousen Satellite No. 1 (KKS-1) microsatellite that was launched by a H2A rocket as one of six piggyback satellites in January 2009.

Gain curves and hydrodynamic modeling for shock ignition

NASA Astrophysics Data System (ADS)

Lafon, M.; Ribeyre, X.; Schurtz, G.

2010-05-01

Ignition of a precompressed thermonuclear fuel by means of a converging shock is now considered as a credible scheme to obtain high gains for inertial fusion energy. This work aims at modeling the successive stages of the fuel time history, from compression to final thermonuclear combustion, in order to provide the gain curves of shock ignition (SI). The leading physical mechanism at work in SI is pressure amplification, at first by spherical convergence, and by collision with the shock reflected at center during the stagnation process. These two effects are analyzed, and ignition conditions are provided as functions of the shock pressure and implosion velocity. Ignition conditions are obtained from a non-isobaric fuel assembly, for which we present a gain model. The corresponding gain curves exhibit a significantly lower ignition threshold and higher target gains than conventional central ignition.

Ignitor with stable low-energy thermite igniting system

DOEpatents

Kelly, Michael D.; Munger, Alan C.

1991-02-05

A stable compact low-energy igniting system in an ignitor utilizes two components, an initiating charge and an output charge. The initiating charge is a thermite in ultra-fine powder form compacted to 50-70% of theoretical maximum density and disposed in a cavity of a header of the ignitor adjacent to an electrical ignition device, or bridgewire, mounted in the header cavity. The initiating charge is ignitable by operation of the ignition device in a hot-wire mode. The output charge is a thermite in high-density consoladated form compacted to 90-99% of theoretical maximum density and disposed adjacent to the initiating charge on an opposite end thereof from the electrical ignition device and ignitable by the initiating charge. A sleeve is provided for mounting the output charge to the ignitor header with the initiating charge confined therebetween in the cavity.

Hydrogen-oxygen catalytic ignition and thruster investigation. Volume 1: Catalytic ignition and low pressure thruster evaluations

NASA Technical Reports Server (NTRS)

Johnson, R. J.

1972-01-01

An experimental and analytical program was conducted to evaluate catalytic igniter operational limits, igniter scaling criteria, and delivered performance of cooled, flightweight gaseous hydrogen-oxygen reaction control thrusters. Specific goals were to: (1) establish operating life and environmental effects for both Shell 405-ABSG and Engelhard MFSA catalysts, (2) provide generalized igniter design guidelines for high response without flashback, and (3) to determine overall performance of thrusters at chamber pressures of 15 and 300 psia (103 and 2068 kN/sq m) and thrust levels of 30 and 1500 lbf, respectively. The experimental results have demonstrated the feasibility of reliable, high response catalytic ignition and the effectiveness of ducted chamber cooling for a high performance flightweight thruster. This volume presents the results of the catalytic igniter and low pressure thruster evaluations are presented.

X-33 Combustion-Wave Ignition System Tested

NASA Technical Reports Server (NTRS)

Liou, Larry C.

1999-01-01

The NASA Lewis Research Center, in cooperation with Rocketdyne, the Boeing Company, tested a novel rocket engine ignition system, called the combustion-wave ignition system, in its Research Combustion Laboratory. This ignition system greatly simplifies ignition in rocket engines that have a large number of combustors. The particular system tested was designed and fabricated by Rocketdyne for the national experimental spacecraft, X-33, which uses Rocketdyne s aerospike rocket engines. The goal of the tests was to verify the system design and define its operational characteristics. Results will contribute to the eventual successful flight of X-33. Furthermore, the combustion-wave ignition system, after it is better understood and refined on the basis of the test results and, later, flight-proven onboard X-33, could become an important candidate engine ignition system for our Nation s next-generation reusable launch vehicle.

Catalytic ignition of hydrogen and oxygen propellants

NASA Technical Reports Server (NTRS)

Zurawski, Robert L.; Green, James M.

1988-01-01

An experimental program was conducted to evaluate the catalytic ignition of gaseous hydrogen and oxygen propellants. Shell 405 granular catalyst and a monolithic sponge catalyst were tested. Mixture ratio, mass flow rate, propellant temperature, and back pressure were varied parametrically in testing to determine the operational limits of the catalytic igniter. The test results show that the gaseous hydrogen and oxygen propellant combination can be ignited catalytically using Shell 405 catalyst over a wide range of mixture ratios, mass flow rates, and propellant injection temperatures. These operating conditions must be optimized to ensure reliable ignition for an extended period of time. A cyclic life of nearly 2000, 2 sec pulses at nominal operating conditions was demonstrated with the catalytic igniter. The results of the experimental program and the established operational limits for a catalytic igniter using the Shell 405 catalysts are presented.

Catalytic ignition of hydrogen and oxygen propellants

NASA Technical Reports Server (NTRS)

Zurawski, Robert L.; Green, James M.

1988-01-01

An experimental program was conducted to evaluate the catalytic ignition of gaseous hydrogen and oxygen propellants. Shell 405 granular catalyst and a monolithic sponge catalyst were tested. Mixture ratio, mass flow rate, propellant temperature, and back pressure were varied parametrically in testing to determine the operational limits of the catalytic igniter. The test results show that the gaseous hydrogen and oxygen propellant combination can be ignited catalytically using Shell 405 catalyst over a wide range of mixture ratios, mass flow rates, and propellant injection temperatures. These operating conditions must be optimized to ensure reliable ignition for an extended period of time. A cyclic life of nearly 2000, 2 sec pulses at nominal operating conditions was demonstrated with the catalytic igniter. The results of the experimental program and the established operational limits for a catalytic igniter using the Shell 405 catalyst are presented.

Cross section measurements in the 12C+12C system

NASA Astrophysics Data System (ADS)

Courtin, S.; Jiang, C. L.; Fruet, G.; Heine, M.; Jenkins, D. G.; Adsley, P.; Morris, L. G.; Regan, P. H.; Rudigier, M.; Montanari, D.; Della Negra, S.; de Séréville, N.; Haas, F.; Hammache, F.; Kirsebom, O. S.; Lesrel, J.; Meyer, A.; Montanari, D.; Auranen, K.; Avila, M. L.; Ayangeakaa, A. D.; Back, B. B.; Bottoni, S.; Carpenter, M.; Dickerson, C.; DiGiovine, B.; Greene, J. P.; Henderson, D. J.; Hoffman, C. R.; Janssens, R. V. F.; Kay, B. P.; Kuvin, S. A.; Lauritsen, T.; Pardo, R. C.; Rehm, K. E.; Santiago-Gonzalez, D.; Sethi, J.; Seweryniak, D.; Talwar, R.; Ugalde, C.; Zhu, S.; Deibel, C. M.; Marley, S. T.; Bourgin, D.; Stodel, C.; Lefebvre-Schuhl, A.; Almaraz-Calderon, S.; Fang, X.; Tang, X. D.; Alcorta, M.; Bucher, B.; Albers, M.; Bertone, P.

2018-01-01

The 12C+12C fusion reaction is one of the most important for nuclear astrophysics since it determines the carbon ignition in stellar environments. Two experiments which make use of the gamma-particle coincidence technique to measure the 12C+12C S-factors at deep sub barrier energies are discussed. Results are presented showing a decrease of the S-factor below Ec.m. = 3 MeV.

Ignition Characterization Test Results for the LO2/Ethanol Propellant Combination

NASA Technical Reports Server (NTRS)

Popp, Christopher G.; Robinson, Phillip J.; Veith, Eric M.

2006-01-01

A series of contracts were issued by the Marshall Space Flight Center (MSFC) of the National Aeronautics and Space Administration (NASA) under the auspices of the Exploration Systems Mission Directorate to develop and expand the maturity of candidate technologies considered to be important for future space exploration. One such technology was to determine the viability of incorporating non-toxic propellants for Reaction Control Subsystems (RCS). Contract NAS8-01109 was issued to Aerojet to develop a dual thrust Reaction Control Engine (RCE) that utilized liquid oxygen and ethanol as the propellants. The dual thrust RCE incorporated a primary thrust level of 870 lbf, and a vernier thrust level of 10 - 30 lbf. The preferred RCS approach for the dual thrust RCE was to utilize pressure-fed liquid oxygen (LOX) and ethanol propellants; however, previous dual thrust feasibility testing incorporated GOX/Ethanol igniters as opposed to LOX/Ethanol igniters in the design. GOX/Ethanol was easier to ignite, but this combination had system design implications of providing GOX for the igniters. A LOX/Ethanol igniter was desired; however, extensive LOX/Ethanol ignition data over the anticipated operating range for the dual thrust RCE did not exist. Therefore, Aerojet designed and tested a workhorse LOX igniter to determine LOX/Ethanol ignition characteristics as part of a risk mitigation effort for the dual thrust RCE design. LOX, encompassing potential two-phase flow conditions anticipated being present in real mission applications. A workhorse igniter was designed to accommodate the hll LOX design flowrate, as well as a reduced GOX flowrate. It was reasoned that the initial LOX flow through the igniter would flash to GOX due to the latent heat stored in the hardware, causing a reduced oxygen flowrate because of a choked, or sonic, flow condition through the injection elements. As LOX flow continued, the hardware would chill-in, with the injected oxygen flow transitioning from cold GOX through two-phase flow to subcooled LOX. permitted oxygen state points to be determined in the igniter oxidizer manifold, and gas-side igniter chamber thermocouples provided chamber thermal profile characteristics. The cold flow chamber pressure (P(sub c)) for each test was determined and coupled with the igniter chamber diameter (D(sub c)) to calculate the characteristic quench parameter (P(sub c) x D(sub c)), which was plotted as a function of core mixture ratio, m. Ignition limits were determined over a broad range of valve inlet conditions, and ignition was demonstrated with oxygen inlet conditions that ranged from subcooled 210 R LOX to 486 R GOX. Once ignited at cold GOX conditions, combustion was continuous as the hardware chilled in and the core mixture ratio transitioned from values near 1.0 to over 12.5. Pulsing is required in typical RCS engines; therefore, the workhorse igniter was pulse tested to verify the ability to provide the required ignition for a pulsing RCE. The minimum electrical pulse width (EPW) of the dual thrust RCE was 0.080 seconds.

14 CFR 33.69 - Ignitions system.

Code of Federal Regulations, 2013 CFR

2013-01-01

... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.69 Ignitions system. Each..., except that only one igniter is required for fuel burning augmentation systems. [Amdt. 33-6, 39 FR 35466... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Ignitions system. 33.69 Section 33.69...

14 CFR 33.69 - Ignitions system.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.69 Ignitions system. Each..., except that only one igniter is required for fuel burning augmentation systems. [Amdt. 33-6, 39 FR 35466... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Ignitions system. 33.69 Section 33.69...

14 CFR 33.69 - Ignitions system.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.69 Ignitions system. Each..., except that only one igniter is required for fuel burning augmentation systems. [Amdt. 33-6, 39 FR 35466... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Ignitions system. 33.69 Section 33.69...

Integral low-energy thermite igniter

DOEpatents

Gibson, A.; Haws, L.D.; Mohler, J.H.

1983-05-13

In a thermite igniter/heat source comprising a container holding an internal igniter load, there is provided the improvement wherein the container consists essentially of consumable consolidated thermite having a low gas output upon combustion, whereby upon ignition, substantially all of the container and said load is consumed with low gas production.

14 CFR 23.1165 - Engine ignition systems.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine ignition systems. 23.1165 Section 23... Controls and Accessories § 23.1165 Engine ignition systems. (a) Each battery ignition system must be... allow continued engine operation if any battery becomes depleted. (b) The capacity of batteries and...

14 CFR 29.1165 - Engine ignition systems.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine ignition systems. 29.1165 Section 29... Engine ignition systems. (a) Each battery ignition system must be supplemented with a generator that is automatically available as an alternate source of electrical energy to allow continued engine operation if any...

Integral low-energy thermite igniter

DOEpatents

Gibson, Albert; Haws, Lowell D.; Mohler, Jonathan H.

1984-08-14

In a thermite igniter/heat source comprising a container holding an internal igniter load, there is provided the improvement wherein the container consists essentially of consumable consolidated thermite having a low gas output upon combustion, whereby upon ignition, substantially all of the container and said load is consumed with low gas production.

14 CFR 23.1165 - Engine ignition systems.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine ignition systems. 23.1165 Section 23... Controls and Accessories § 23.1165 Engine ignition systems. (a) Each battery ignition system must be... allow continued engine operation if any battery becomes depleted. (b) The capacity of batteries and...

14 CFR 29.1165 - Engine ignition systems.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine ignition systems. 29.1165 Section 29... Engine ignition systems. (a) Each battery ignition system must be supplemented with a generator that is automatically available as an alternate source of electrical energy to allow continued engine operation if any...

14 CFR 23.1165 - Engine ignition systems.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine ignition systems. 23.1165 Section 23... Controls and Accessories § 23.1165 Engine ignition systems. (a) Each battery ignition system must be... allow continued engine operation if any battery becomes depleted. (b) The capacity of batteries and...

14 CFR 29.1165 - Engine ignition systems.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine ignition systems. 29.1165 Section 29... Engine ignition systems. (a) Each battery ignition system must be supplemented with a generator that is automatically available as an alternate source of electrical energy to allow continued engine operation if any...

14 CFR 25.1165 - Engine ignition systems.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine ignition systems. 25.1165 Section 25... Engine ignition systems. (a) Each battery ignition system must be supplemented by a generator that is automatically available as an alternate source of electrical energy to allow continued engine operation if any...

Compression Ratio and Catalyst Aging Effects on Aqueous Ethanol Ignition (Year 2): Part 1. Compression Ratio Effects on Aqueous Ethanol Ignition

DOT National Transportation Integrated Search

2009-09-01

The lean burning of water ethanol blends has the potential to reduce NOx, CO, and HC emissions while reducing the ethanol fermentation production cost of distillation and dehydration. The torch style ignition produced by the catalytic igniter allows ...

14 CFR 33.37 - Ignition system.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ignition system. 33.37 Section 33.37 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.37 Ignition system. Each spark ignition engine must have a...

Ignition and Flame Development in the Case of Diesel Fuel Injection

NASA Technical Reports Server (NTRS)

Holfelder, Otto

1936-01-01

To investigate the process of ignition and combustion in the case of spray injection into heated air, a new form of apparatus is developed and the tests carried out with it described. Photographs of the spray before and after ignition are obtained at frequencies of 500 pictures per second. Pressures and temperatures are simultaneously recorded on oscillograms. Information on the initial conditions, ignition time lag, period of complete combustion, place where ignition starts, and general course of the combustion is obtained.

Ignition of Fuel Vapors Beneath Titanium Aircraft Skins Exposed to Lightning

NASA Technical Reports Server (NTRS)

Kosvic, T. C.; Helgeson, N. L.; Gerstein, M.

1971-01-01

Hot-spot and puncture ignition of fuel vapors by simulated lightning discharges was studied experimentally. The influences of skin coating, skin structure, discharge polarity, skin thickness, discharge current level, and current duration were measured and interpreted. Ignition thresholds are reported for titanium alloy constructed as sheets, sheets coated with sealants, and sandwich skins. Results indicated that the ignition threshold charge transfer for coated sheets, honeycomb, and truss skins is respectively about 200%, 400%, 800% that of bare alloy sheet of .102 cm (.040 in.)-thickness. It was found that hot-spot ignition can occur well after termination of the arc, and that sandwich materials allow ignition only if punctured.

Ignition process in Diesel engines

NASA Technical Reports Server (NTRS)

Wentzel, W

1936-01-01

This report analyzes the heating and vaporization process of fuel droplets in a compression-ignition engine on the basis of the theory of similitude - according to which, the period for heating and complete vaporization of the average size fuel drop is only a fraction of the actually observed ignition lag. The result is that ignition takes place in the fuel vapor air mixture rather than on the surface of the drop. The theoretical result is in accord with the experimental observations by Rothrock and Waldron. The combustion shock occurring at lower terminal compression temperature, especially in the combustion of coal-tar oil, is attributable to a simultaneous igniting of a larger fuel-vapor volume formed prior to ignition.

Influence of coal particles on ignition delay times of methane-air mixture

NASA Astrophysics Data System (ADS)

Fedorov, A. V.; Tropin, D. A.

2018-03-01

The results of numerical investigation of the ignition of a stoichiometric methane-air mixture in the presence of carbon particles with diameters of 20-52 μm in the temperature range 950-1150 K and pressures of 1.5-2.0 MPa are presented. The calculated data of the ignition delay times of coal particles in the coal particles/air mixture and of the ignition delay times of methane and coal particles in the methane/coal particles /air mixture are compared with the experimental ones. A satisfactory agreement of the data on the coal particles ignition delay times and methane ignition delay times in all the mixtures considered is shown.

Influence of radiative processes on the ignition of deuterium–tritium plasma containing inactive impurities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gus’kov, S. Yu., E-mail: guskov@sci.lebedev.ru; Sherman, V. E.

2016-08-15

The degree of influence of radiative processes on the ignition of deuterium–tritium (DT) plasma has been theoretically studied as dependent on the content of inactive impurities in plasma. The analytic criterion of plasma ignition in inertial confinement fusion (ICF) targets is modified taking into account the absorption of intrinsic radiation from plasma in the ignition region. The influence of radiative processes on the DT plasma ignition has been analytically and numerically studied for plasma that contains a significant fraction of inactive impurities either as a result of DT fuel mixing with ICF target ablator material or as a result ofmore » using light metal DT-hydrides as solid noncryogenic fuel. It has been shown that the effect of the absorption of intrinsic radiation leads to lower impurity-induced increase in the ignition energy as compared to that calculated in the approximation of optically transparent ignition region.« less

Determination of parameters used to prevent ignition of stored materials and to protect against explosions in food industries.

PubMed

Ramírez, Alvaro; García-Torrent, Javier; Aguado, Pedro J

2009-08-30

There are always risks associated with silos when the stored material has been characterized as prone to self-ignition or explosion. Further research focused on the characterization of agricultural materials stored in silos is needed due to the lack of data found in the literature. The aim of this study was to determine the ignitability and explosive parameters of several agricultural products commonly stored in silos in order to assess the risk of ignition and dust explosion. Minimum Ignition Temperature, with dust forming a cloud and deposited in a layer, Lower Explosive Limit, Minimum Ignition Energy, Maximum Explosion Pressure and Maximum Explosion Pressure Rise were determined for seven agricultural materials: icing sugar, maize, wheat and barley grain dust, alfalfa, bread-making wheat and soybean dust. Following characterization, these were found to be prone to producing self-ignition when stored in silos under certain conditions.

Capsule performance optimization in the National Ignition Campaigna)

NASA Astrophysics Data System (ADS)

Landen, O. L.; Boehly, T. R.; Bradley, D. K.; Braun, D. G.; Callahan, D. A.; Celliers, P. M.; Collins, G. W.; Dewald, E. L.; Divol, L.; Glenzer, S. H.; Hamza, A.; Hicks, D. G.; Hoffman, N.; Izumi, N.; Jones, O. S.; Kirkwood, R. K.; Kyrala, G. A.; Michel, P.; Milovich, J.; Munro, D. H.; Nikroo, A.; Olson, R. E.; Robey, H. F.; Spears, B. K.; Thomas, C. A.; Weber, S. V.; Wilson, D. C.; Marinak, M. M.; Suter, L. J.; Hammel, B. A.; Meyerhofer, D. D.; Atherton, J.; Edwards, J.; Haan, S. W.; Lindl, J. D.; MacGowan, B. J.; Moses, E. I.

2010-05-01

A capsule performance optimization campaign will be conducted at the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, 228 (2004)] to substantially increase the probability of ignition by laser-driven hohlraums [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)]. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the OMEGA facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

Capsule performance optimization in the National Ignition Campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landen, O. L.; Bradley, D. K.; Braun, D. G.

2010-05-15

A capsule performance optimization campaign will be conducted at the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, 228 (2004)] to substantially increase the probability of ignition by laser-driven hohlraums [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)]. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the OMEGA facility under scaled hohlraum and capsule conditions relevant to the ignition designmore » and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.« less

46 CFR 160.037-3 - Materials, workmanship, construction, and performance requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... on its top with a friction striking material which shall, by a pull of the tear strip, be entirely exposed for striking the friction igniter button. The igniter button shall be non-water soluble or be... manner as to provide positive ignition by the friction striker. The igniter button shall be firmly...

46 CFR 160.037-3 - Materials, workmanship, construction, and performance requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... on its top with a friction striking material which shall, by a pull of the tear strip, be entirely exposed for striking the friction igniter button. The igniter button shall be non-water soluble or be... manner as to provide positive ignition by the friction striker. The igniter button shall be firmly...

46 CFR 160.037-3 - Materials, workmanship, construction, and performance requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... on its top with a friction striking material which shall, by a pull of the tear strip, be entirely exposed for striking the friction igniter button. The igniter button shall be non-water soluble or be... manner as to provide positive ignition by the friction striker. The igniter button shall be firmly...

46 CFR 160.037-3 - Materials, workmanship, construction, and performance requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... on its top with a friction striking material which shall, by a pull of the tear strip, be entirely exposed for striking the friction igniter button. The igniter button shall be non-water soluble or be... manner as to provide positive ignition by the friction striker. The igniter button shall be firmly...

Ignition and combustion phenomena in Diesel engines

NASA Technical Reports Server (NTRS)

Sass, F

1928-01-01

Evidences were found that neither gasification nor vaporization of the injected fuel occurs before ignition; also that the hydrogen coefficient has no significance. However the knowledge of the ignition point and of the "time lag" is important. After ignition, the combustion proceeds in a series of reactions, the last of which at least are now known.

Final Rule for Gasoline Spark-Ignition Marine Engines; Exemptions for New Nonroad Compression-Ignition Engines at or Above 37 Kilowatts and New Nonroad Spark-Ignition Engines at or Below 19 Kilowatts

EPA Pesticide Factsheets

These standards apply for outboard engines, personal watercraft engines, and jet boat engines. This rule also adds a national security exemption for Nonroad Compression-Ignition (CI) and Small SI sectors.

Structure ignition assessment model (SIAM)\\t

Treesearch

Jack D. Cohen

1995-01-01

Major wildland/urban interface fire losses, principally residences, continue to occur. Although the problem is not new, the specific mechanisms are not well known on how structures ignite in association with wildland fires. In response to the need for a better understanding of wildland/urban interface ignition mechanisms and a method of assessing the ignition risk,...

Moisture Content Influences Ignitability of Slash Pine Litter

Treesearch

Winfred H. Blackmarr

1972-01-01

The influence of moisture content on the ignitability of slash pine litter was measured by dropping lighted matches onto fuel beds conditioned to different levels of moisture content.The percentage of matches igniting the fuel bed was used to indicate ignition probability at each moisture content. The "critical range" of fuel moisture contents within which...

46 CFR 147A.43 - Other sources of ignition; flammable fumigants.

Code of Federal Regulations, 2010 CFR

2010-10-01

... sources of ignition; flammable fumigants. While the space that is fumigated is being sealed or during fumigation, no person may use matches, smoking materials, fires, open flames, or any other source of ignition... 46 Shipping 5 2010-10-01 2010-10-01 false Other sources of ignition; flammable fumigants. 147A.43...

Determining Acceptable Limits of Fast-Electron Preheat in Polar-Drive-Ignition Designs

NASA Astrophysics Data System (ADS)

Delettrez, J. A.; Collins, T. J. B.; Ye, C.

2014-10-01

In direct-drive-ignition designs, preheat by fast electrons created by the two-plasmon-decay instability at the quarter-critical density surface can increase the adiabat in the fuel layer and prevent ignition. Since eliminating the preheat entirely is not possible, it is necessary to understand the levels of preheat our targets can withstand before ignition is precluded. The current polar-drive point design is used as the basis for examining the effects of increasing the levels of fast electrons using the one-dimensional, radiation-hydrodynamics code LILAC. Once ignition failure is obtained, the design is then reoptimized using Telios, a downhill simplex method program, to recover ignition. This cycle is repeated until the design can no longer be reoptimized to produce ignition. Mappings of these final results provide insight into ignition failure caused by preheat and what specific target parameters serve to best stave off the effects of the preheat. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Development and Testing of a Green Monopropellant Ignition System

NASA Technical Reports Server (NTRS)

Whitmore, Stephen A.; Merkley, Daniel P.; Eilers, Shannon D.; Judson, Michael I.; Taylor, Terry L.

2013-01-01

This paper will detail the development and testing of a "green" monopropellant booster ignition system. The proposed booster ignition technology eliminates the need for a pre-heated catalyst bed, a high wattage power source, toxic pyrophoric ignition fluids, or a bi-propellant spark ignitor. The design offers the simplicity of a monopropellant feed system features non-hazardous gaseous oxygen (GOX) as the working fluid. The approach is fundamentally different from all other "green propellant" solutions in the aerospace in the industry. Although the proposed system is more correctly a "hybrid" rocket technology, since only a single propellant feed path is required, it retains all the simple features of a monopropellant system. The technology is based on the principle of seeding an oxidizing flow with a small amount of hydrocarbon.1 The ignition is initiated electrostatically with a low-wattage inductive spark. Combustion gas byproducts from the hydrocarbon-seeding ignition process can exceed 2400 C and the high exhaust temperature ensures reliable main propellant ignition. The system design is described in detail in the Hydrocarbon-Seeded Ignition System Design subsection.

Technology Development of a Fiber Optic-Coupled Laser Ignition System for Multi-Combustor Rocket Engines

NASA Technical Reports Server (NTRS)

Trinh, Huu P.; Early, Jim; Osborne, Robin; Thomas, Matthew E.; Bossard, John A.

2002-01-01

This paper addresses the progress of technology development of a laser ignition system at NASA Marshall Space Flight Center (MSFC). The first two years of the project focus on comprehensive assessments and evaluations of a novel dual-pulse laser concept, flight- qualified laser system, and the technology required to integrate the laser ignition system to a rocket chamber. With collaborations of the Department of Energy/Los Alamos National Laboratory (LANL) and CFD Research Corporation (CFDRC), MSFC has conducted 26 hot fire ignition tests with lab-scale laser systems. These tests demonstrate the concept feasibility of dual-pulse laser ignition to initiate gaseous oxygen (GOX)/liquid kerosene (RP-1) combustion in a rocket chamber. Presently, a fiber optic- coupled miniaturized laser ignition prototype is being implemented at the rocket chamber test rig for future testing. Future work is guided by a technology road map that outlines the work required for maturing a laser ignition system. This road map defines activities for the next six years, with the goal of developing a flight-ready laser ignition system.

Space Shuttle SRM Ignition System. [Solid Rocket Motor

NASA Technical Reports Server (NTRS)

Bolieau, C. W.; Baker, J. S.; Folkman, S. L.

1978-01-01

This paper presents the Space Shuttle SRM Ignition System, which consists of a large solid propellant main igniter, a small solid propellant initiating igniter and an electromechanical safety and arming device containing two NASA Standard Initiators and a B-KNO3 pyrotechnic booster charge. In development motors, the igniter also has a valve through which CO2 is injected for post-firing quench of the SRM. The igniter has redundant, testable seals at all pressurized joints and three major reusable components; the case, the adapter, and the S&A device. Two development problem areas are discussed. One problem area was transverse mode combustion instability in the main igniter with maximum amplitude of 340 psi peak-to-peak at a frequency of 1500 Hz, which was reduced by a propellant grain configuration change and a change from a 2% aluminum content propellant to a formulation containing 10% aluminum. The other problem area was an excessively rapid rise of thrust in the SRM, which was reduced by reducing the igniter mass flow rate. This mass flow rate reduction was accomplished by removing portions of the grain starpoints in the head end.

Ignition in an Atomistic Model of Hydrogen Oxidation.

PubMed

Alaghemandi, Mohammad; Newcomb, Lucas B; Green, Jason R

2017-03-02

Hydrogen is a potential substitute for fossil fuels that would reduce the combustive emission of carbon dioxide. However, the low ignition energy needed to initiate oxidation imposes constraints on the efficiency and safety of hydrogen-based technologies. Microscopic details of the combustion processes, ephemeral transient species, and complex reaction networks are necessary to control and optimize the use of hydrogen as a commercial fuel. Here, we report estimates of the ignition time of hydrogen-oxygen mixtures over a wide range of equivalence ratios from extensive reactive molecular dynamics simulations. These data show that the shortest ignition time corresponds to a fuel-lean mixture with an equivalence ratio of 0.5, where the number of hydrogen and oxygen molecules in the initial mixture are identical, in good agreement with a recent chemical kinetic model. We find two signatures in the simulation data precede ignition at pressures above 200 MPa. First, there is a peak in hydrogen peroxide that signals ignition is imminent in about 100 ps. Second, we find a strong anticorrelation between the ignition time and the rate of energy dissipation, suggesting the role of thermal feedback in stimulating ignition.

The effect of climate anomalies and human ignition factor on wildfires in Russian boreal forests.

PubMed

Achard, Frédéric; Eva, Hugh D; Mollicone, Danilo; Beuchle, René

2008-07-12

Over the last few years anomalies in temperature and precipitation in northern Russia have been regarded as manifestations of climate change. During the same period exceptional forest fire seasons have been reported, prompting many authors to suggest that these in turn are due to climate change. In this paper, we examine the number and areal extent of forest fires across boreal Russia for the period 2002-2005 within two forest categories: 'intact forests' and 'non-intact forests'. Results show a far lower density of fire events in intact forests (5-14 times less) and that those events tend to be in the first 10 km buffer zone inside intact forest areas. Results also show that, during exceptional climatic years (2002 and 2003), fire event density is twice that found during normal years (2004 and 2005) and average areal extent of fire events (burned area) in intact forests is 2.5 times larger than normal. These results suggest that a majority of the fire events in boreal Russia are of human origin and a maximum of one-third of their impact (areal extension) can be attributed to climate anomalies alone, the rest being due to the combined effect of human disturbances and climate anomalies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blijderveen, Maarten van; University of Twente, Department of Thermal Engineering, Drienerlolaan 5, 7522 NB Enschede; Bramer, Eddy A.

Highlights: Black-Right-Pointing-Pointer We model piloted ignition times of wood and plastics. Black-Right-Pointing-Pointer The model is applied on a packed bed. Black-Right-Pointing-Pointer When the air flow is above a critical level, no ignition can take place. - Abstract: To gain insight in the startup of an incinerator, this article deals with piloted ignition. A newly developed model is described to predict the piloted ignition times of wood, PMMA and PVC. The model is based on the lower flammability limit and the adiabatic flame temperature at this limit. The incoming radiative heat flux, sample thickness and moisture content are some of themore » used variables. Not only the ignition time can be calculated with the model, but also the mass flux and surface temperature at ignition. The ignition times for softwoods and PMMA are mainly under-predicted. For hardwoods and PVC the predicted ignition times agree well with experimental results. Due to a significant scatter in the experimental data the mass flux and surface temperature calculated with the model are hard to validate. The model is applied on the startup of a municipal waste incineration plant. For this process a maximum allowable primary air flow is derived. When the primary air flow is above this maximum air flow, no ignition can be obtained.« less

Prechamber equipped laser ignition for improved performance in natural gas engines

DOE PAGES

Almansour, Bader; Vasu, Subith; Gupta, Sreenath B.; ...

2017-04-25

Lean-burn operation of stationary natural gas engines offers lower NO x emissions and improved efficiency. A proven pathway to extend lean-burn operation has been to use laser ignition instead of standard spark ignition. However, under lean conditions, flame speed reduces thereby offsetting any efficiency gains resulting from the higher ratio of specific heats, γ. The reduced flame speeds, in turn, can be compensated with the use of a prechamber to result in volumetric ignition, and thereby lead to faster combustion. In this study, the optimal geometry of PCLI was identified through several tests in a single-cylinder engine as a compromisemore » between autoignition, NO x and soot formation within the prechamber. Subsequently, tests were conducted in a single-cylinder natural gas engine comparing the performance of three ignition systems: standard electrical spark ignition (SI), single-point laser ignition (LI), and prechamber equipped laser ignition (PCLI). Out of the three, the performance of PCLI was far superior compared to the other two. Efficiency gain of 2.1% points could be achieved while complying with EPA regulation (BSNO x < 1.34 kW-hr) and the industry standard for ignition stability (COV_IMEP < 5%). Finally, test results and data analysis are presented identifying the combustion mechanisms leading to the improved performance.« less

DNS study of the ignition of n-heptane fuel spray under high pressure and lean conditions

NASA Astrophysics Data System (ADS)

Wang, Yunliang; Rutland, Christopher J.

2005-01-01

Direct numerical simulations (DNS) are used to investigate the ignition of n-heptane fuel spray under high pressure and lean conditions. For the solution of the carrier gas fluid, the Eulerian method is employed, while for the fuel spray, the Lagrangian method is used. A chemistry mechanism for n-heptane with 33 species and 64 reactions is adopted to describe the chemical reactions. Initial carrier gas temperature and pressure are 926 K and 30.56 atmospheres, respectively. Initial global equivalence ratio is 0.258. Two cases with droplet radiuses of 35.5 and 20.0 macrons are simulated. Evolutions of the carrier gas temperature and species mass fractions are presented. Contours of the carrier gas temperature and species mass fractions near ignition and after ignition are presented. The results show that the smaller fuel droplet case ignites earlier than the larger droplet case. For the larger droplet case, ignition occurs first at one location; for the smaller droplet case, however, ignition occurs first at multiple locations. At ignition kernels, significant NO is produced when temperature is high enough at the ignition kernels. For the larger droplet case, more NO is produced than the smaller droplet case due to the inhomogeneous distribution and incomplete mixing of fuel vapor.

The Feasibility of Applying AC Driven Low-Temperature Plasma for Multi-Cycle Detonation Initiation

NASA Astrophysics Data System (ADS)

Zheng, Dianfeng

2016-11-01

Ignition is a key system in pulse detonation engines (PDE). As advanced ignition methods, nanosecond pulse discharge low-temperature plasma ignition is used in some combustion systems, and continuous alternating current (AC) driven low-temperature plasma using dielectric barrier discharge (DBD) is used for the combustion assistant. However, continuous AC driven plasmas cannot be used for ignition in pulse detonation engines. In this paper, experimental and numerical studies of pneumatic valve PDE using an AC driven low-temperature plasma igniter were described. The pneumatic valve was jointly designed with the low-temperature plasma igniter, and the numerical simulation of the cold-state flow field in the pneumatic valve showed that a complex flow in the discharge area, along with low speed, was beneficial for successful ignition. In the experiments ethylene was used as the fuel and air as oxidizing agent, ignition by an AC driven low-temperature plasma achieved multi-cycle intermittent detonation combustion on a PDE, the working frequency of the PDE reached 15 Hz and the peak pressure of the detonation wave was approximately 2.0 MPa. The experimental verifications of the feasibility in PDE ignition expanded the application field of AC driven low-temperature plasma. supported by National Natural Science Foundation of China (No. 51176001)

Concepts in Building Firesafety.

ERIC Educational Resources Information Center

Egan, M. David

The goal of this book is to present in a graphical format the principles of design for building firesafety. The book's more than 270 illustrations represent the core of its coverage of factors affecting fire ignition and spread in buildings, building site planning for fire suppression and occupant rescue operations, protection by building…

Foliar Moisture Contents of North American Conifers

Treesearch

Christopher R. Keyes

2006-01-01

Foliar moisture content (FMC) is a primary factor in the canopy ignition process as surface fire transitions to crown fire. In combination with measured stand data and assumed environmental conditions, reasonable estimates of foliar moisture content are necessary to determine and justify silvicultural targets for canopy fuels management strategies. FMC values reported...

Combustion chemistry of ethanol: Ignition and speciation studies in a rapid compression facility [On the combustion chemistry of ethanol: Ignition and speciation studies in a rapid compression facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barraza-Botet, Cesar L.; Wagnon, Scott W.; Wooldridge, Margaret S.

Here, ethanol remains the most important alternative fuel for the transportation sector. This work presents new experimental data on ethanol ignition, including stable species measurements, obtained with the University of Michigan rapid compression facility. Ignition delay times were determined from pressure histories of ignition experiments with stoichiometric ethanol–air mixtures at pressures of ~3–10 atm. Temperatures (880–1150 K) were controlled by varying buffer gas composition (Ar, N 2, CO 2). High-speed imaging was used to record chemiluminescence during the experiments, which showed homogeneous ignition events. The results for ignition delay time agreed well with trends on the basis of previous experimentalmore » measurements. Speciation experiments were performed using fast gas sampling and gas chromatography to identify and quantify ethanol and 11 stable intermediate species formed during the ignition delay period. Simulations were carried out using a chemical kinetic mechanism available in the literature, and the agreement with the experimental results for ignition delay time and the intermediate species measured was excellent for the majority of the conditions studied. From the simulation results, ethanol + HO 2 was identified as an important reaction at the experimental conditions for both the ignition delay time and intermediate species measurements. Further studies to improve the accuracy of the rate coefficient for ethanol + HO 2 would improve the predictive understanding of intermediate and low-temperature ethanol combustion.« less

Combustion chemistry of ethanol: Ignition and speciation studies in a rapid compression facility [On the combustion chemistry of ethanol: Ignition and speciation studies in a rapid compression facility

DOE PAGES

Barraza-Botet, Cesar L.; Wagnon, Scott W.; Wooldridge, Margaret S.

2016-08-31

Here, ethanol remains the most important alternative fuel for the transportation sector. This work presents new experimental data on ethanol ignition, including stable species measurements, obtained with the University of Michigan rapid compression facility. Ignition delay times were determined from pressure histories of ignition experiments with stoichiometric ethanol–air mixtures at pressures of ~3–10 atm. Temperatures (880–1150 K) were controlled by varying buffer gas composition (Ar, N 2, CO 2). High-speed imaging was used to record chemiluminescence during the experiments, which showed homogeneous ignition events. The results for ignition delay time agreed well with trends on the basis of previous experimentalmore » measurements. Speciation experiments were performed using fast gas sampling and gas chromatography to identify and quantify ethanol and 11 stable intermediate species formed during the ignition delay period. Simulations were carried out using a chemical kinetic mechanism available in the literature, and the agreement with the experimental results for ignition delay time and the intermediate species measured was excellent for the majority of the conditions studied. From the simulation results, ethanol + HO 2 was identified as an important reaction at the experimental conditions for both the ignition delay time and intermediate species measurements. Further studies to improve the accuracy of the rate coefficient for ethanol + HO 2 would improve the predictive understanding of intermediate and low-temperature ethanol combustion.« less

A multi-step reaction model for ignition of fully-dense Al-CuO nanocomposite powders

NASA Astrophysics Data System (ADS)

Stamatis, D.; Ermoline, A.; Dreizin, E. L.

2012-12-01

A multi-step reaction model is developed to describe heterogeneous processes occurring upon heating of an Al-CuO nanocomposite material prepared by arrested reactive milling. The reaction model couples a previously derived Cabrera-Mott oxidation mechanism describing initial, low temperature processes and an aluminium oxidation model including formation of different alumina polymorphs at increased film thicknesses and higher temperatures. The reaction model is tuned using traces measured by differential scanning calorimetry. Ignition is studied for thin powder layers and individual particles using respectively the heated filament (heating rates of 103-104 K s-1) and laser ignition (heating rate ∼106 K s-1) experiments. The developed heterogeneous reaction model predicts a sharp temperature increase, which can be associated with ignition when the laser power approaches the experimental ignition threshold. In experiments, particles ignited by the laser beam are observed to explode, indicating a substantial gas release accompanying ignition. For the heated filament experiments, the model predicts exothermic reactions at the temperatures, at which ignition is observed experimentally; however, strong thermal contact between the metal filament and powder prevents the model from predicting the thermal runaway. It is suggested that oxygen gas release from decomposing CuO, as observed from particles exploding upon ignition in the laser beam, disrupts the thermal contact of the powder and filament; this phenomenon must be included in the filament ignition model to enable prediction of the temperature runaway.

Influence of ignition process on mineral phase transformation in municipal solid waste incineration (MSWI) fly ash: Implications for estimating loss-on-ignition (LOI).

PubMed

Mu, Yue; Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki

2017-01-01

This research focused on the mineral phase transformation under varied ignition conditions with the objective of estimating loss-on-ignition (LOI) parameter in municipal solid waste incineration (MSWI) fly ash residues. LOI is commonly used to measure the volatile species, unburned carbon and moisture in the solid materials. There are criteria for LOI measurement in some research fields, while there is no standard protocol for LOI measurement in MSWI fly ash. Using thermogravimetry technique, the ignition condition candidates were proposed at 440/700/900°C for 1 and 2h. Based on X-ray diffractometry results, obvious mineral phase transformation occurred as a function of ignition temperature variation rather than ignition time. Until 440°C, only some minor phases disappeared comparing with the original state. Significant mineral phase transformations of major phases (Ca- and Cl-based minerals) occurred between 440 and 700°C. The mineral phase transformation and the occurrence of newly-formed phases were determined not only by the ignition condition but also by the content of the co-existing components. Mineral phase components rarely changed when ignition temperature rose from 700 to 900°C. Consequently, in order to prevent critical damages to the original mineralogical composition of fly ash, the lowest ignition temperature (440°C) for 2h was suggested as an ideal measurement condition of LOI in MSWI fly ash. Copyright © 2016 Elsevier Ltd. All rights reserved.

High-speed OH* chemiluminescence imaging of ignition through a shock tube end-wall

NASA Astrophysics Data System (ADS)

Troutman, V. A.; Strand, C. L.; Campbell, M. F.; Tulgestke, A. M.; Miller, V. A.; Davidson, D. F.; Hanson, R. K.

2016-03-01

A high-speed OH* chemiluminescence imaging diagnostic was developed to image the structure and homogeneity of combustion events behind reflected shock waves in the Stanford Constrained Reaction Volume Shock Tube. An intensified high-repetition-rate imaging system was used to acquire images of OH* chemiluminescence (near 308 nm) through a fused quartz shock tube end-wall window at 10-33 kHz during the combustion of n-heptane (21 % O2/Ar, φ = 0.5). In general, the imaging technique enabled observation of the main ignition event in the core of the shock tube that corresponded to typical markers of ignition (e.g., pressure rise), as well as localized ignition near the wall that preceded the main core ignition event for some conditions. Case studies were performed to illustrate the utility of this novel imaging diagnostic. First, by comparing localized wall ignition events to the core ignition event, the temperature homogeneity of the post-reflected shock gas near the end-wall was estimated to be within 0.5 % for the test condition presented (T=1159 hbox {K}, P=0.25 hbox {MPa}). Second, the effect of a recession in the shock tube wall, created by an observation window, on the combustion event was visualized. Localized ignition was observed near the window, but this disturbance did not propagate to the core of the shock tube before the main ignition event. Third, the effect of shock tube cleanliness was investigated by conducting tests in which the shock tube was not cleaned for multiple consecutive runs. For tests after no cleaning was performed, ignition events were concentrated in the lower half of the shock tube. In contrast, when the shock tube was cleaned, the ignition event was distributed around the entire circumference of the shock tube; validating the cleaning procedure.

Effects of injection parameters, boost, and swirl ratio on gasoline compression ignition operation at idle and low-load conditions

DOE PAGES

Kodavasal, Janardhan; Kolodziej, Christopher P.; Ciatti, Stephen A.; ...

2016-11-03

In this study, we study the effects of injector nozzle inclusion angle, injection pressure, boost, and swirl ratio on gasoline compression ignition combustion. Closed-cycle computational fluid dynamics simulations using a 1/7th sector mesh representing a single cylinder of a four-cylinder 1.9 L diesel engine, operated in gasoline compression ignition mode with 87 anti-knock index (AKI) gasoline, were performed. Two different operating conditions were studied—the first is representative of idle operation (4 mg fuel/cylinder/cycle, 850 r/min), and the second is representative of a low-load condition (10 mg fuel/cylinder/cycle, 1500 r/min). The mixture preparation and reaction space from the simulations were analyzedmore » to gain insights into the effects of injection pressure, nozzle inclusion angle, boost, and swirl ratio on achieving stable low-load to idle gasoline compression ignition operation. It was found that narrower nozzle inclusion angles allow for more reactivity or propensity to ignition (determined qualitatively by computing constant volume ignition delays) and are suitable over a wider range of injection timings. Under idle conditions, it was found that lower injection pressures helped to reduce overmixing of the fuel, resulting in greater reactivity and ignitability (ease with which ignition can be achieved) of the gasoline. However, under the low-load condition, lower injection pressures did not increase ignitability, and it is hypothesized that this is because of reduced chemical residence time resulting from longer injection durations. Reduced swirl was found to maintain higher in-cylinder temperatures through compression, resulting in better ignitability. It was found that boosting the charge also helped to increase reactivity and advanced ignition timing.« less

Modes of Ignition of Powder Layers of Nanocomposite Thermites by Electrostatic Discharge

NASA Astrophysics Data System (ADS)

Monk, I.; Schoenitz, M.; Dreizin, E. L.

2017-01-01

Nanocomposite powders with aluminum as a fuel and oxides of molybdenum, copper, bismuth, and iron as oxidizers were prepared by arrested reactive milling. The powders were placed in 0.5-mm-thick layers and ignited by electrostatic discharge (ESD) in air. In different tests, time-resolved light emission was recorded at 568 nm or in the range of 373-641 nm. The amount of material consumed was recorded as well. Time-resolved temperatures were determined. Two distinct ignition regimes were observed. Prompt ignition occurred within 10 µs of the electric discharge, comparable to what had previously been observed for corresponding powder monolayers. This ignition mode was observed for composites with Bi2O3 and Fe2O3 ignited with a 12-kV discharge, whereas it only occurred at higher spark voltage (20 kV) and energy for CuO and MoO3 composites. Delayed ignition, occurring after 0.1-1 ms following the discharge, was observed for all composites with consistently stronger light emission. Analysis of quenched, partially burned particles showed that the original nanostructure was preserved after prompt ignition but not after delayed ignition. It is proposed that prompt ignition represents direct ESD initiation of composite particles rapidly and adiabatically preheated to high temperatures while keeping the nanostructure intact, resulting in a heterogeneous reaction consuming most of the aluminum. Delayed ignition occurs when particles preheated to lower temperatures start oxidizing at much lower rates, leading to cloud combustion, in which thermal interaction between individual aerosolized burning particles is substantial. During this process, the nanostructure may be lost. Temperature measurements show that nanocomposites with CuO and MoO3 burned superadiabatically with flame temperatures exceeding thermodynamic predictions.

Effects of injection parameters, boost, and swirl ratio on gasoline compression ignition operation at idle and low-load conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kodavasal, Janardhan; Kolodziej, Christopher P.; Ciatti, Stephen A.

In this study, we study the effects of injector nozzle inclusion angle, injection pressure, boost, and swirl ratio on gasoline compression ignition combustion. Closed-cycle computational fluid dynamics simulations using a 1/7th sector mesh representing a single cylinder of a four-cylinder 1.9 L diesel engine, operated in gasoline compression ignition mode with 87 anti-knock index (AKI) gasoline, were performed. Two different operating conditions were studied—the first is representative of idle operation (4 mg fuel/cylinder/cycle, 850 r/min), and the second is representative of a low-load condition (10 mg fuel/cylinder/cycle, 1500 r/min). The mixture preparation and reaction space from the simulations were analyzedmore » to gain insights into the effects of injection pressure, nozzle inclusion angle, boost, and swirl ratio on achieving stable low-load to idle gasoline compression ignition operation. It was found that narrower nozzle inclusion angles allow for more reactivity or propensity to ignition (determined qualitatively by computing constant volume ignition delays) and are suitable over a wider range of injection timings. Under idle conditions, it was found that lower injection pressures helped to reduce overmixing of the fuel, resulting in greater reactivity and ignitability (ease with which ignition can be achieved) of the gasoline. However, under the low-load condition, lower injection pressures did not increase ignitability, and it is hypothesized that this is because of reduced chemical residence time resulting from longer injection durations. Reduced swirl was found to maintain higher in-cylinder temperatures through compression, resulting in better ignitability. It was found that boosting the charge also helped to increase reactivity and advanced ignition timing.« less

Overview of the National Ignition Campaign (NIC)

NASA Astrophysics Data System (ADS)

Moses, Edward

2010-11-01

The 192-beam National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is now operational. NIF has conducted 192-beam implosion experiments with energies as high as 1.2 MJ and has also demonstrated the unprecedented energy and pulse shaping control required for ignition experiments. The successful commissioning of the NIF laser is the first step in demonstrating inertial confinement fusion (ICF) ignition in the laboratory. The NIF ignition program is executed via the National Ignition Campaign (NIC)---a partnership between Los Alamos National Laboratory, Lawrence Berkeley Laboratory, LLNL, General Atomics, the University of Rochester Laboratory for Laser Energetics, Sandia National Laboratories, the Massachusetts Institute of Technology, and other national and international partners. The NIC relies on a novel integrated experimental and computational program to tune the target to the conditions required for indirect-drive ignition. This approach breaks the tuning process into four phases. The first two phases involve tuning of the hohlraum and capsule to produce the correct radiation drive, symmetry, and shock timing conditions. The third phase consists of layered cryogenic implosions conducted with a 50%/49%/1% mixture of tritium, hydrogen, and deuterium (THD) respectively. The reduced yield from these THD targets allows the full diagnostic suite to be employed and the presence of the required temperature and fuel areal density to be verified. The final step is DT ignition implosions with expected gains of 10-20. DT ignition experiments will be conducted with Elaser ˜1.2 MJ. Laser energies of 1.8 MJ should be available for subsequent experiments. This talk will review the multi-phase tuning approach to the ignition effort, including the physics issues associated with the various steps, and current and future plans for the NIF ignition program.

Full-Scale Experimental Investigation to Quantify Building Component Ignition Vulnerability from Mulch Beds Attacked by Firebrand Showers.

PubMed

Manzello, Samuel L; Suzuki, Sayaka; Nii, Daisaku

2017-03-01

Structure ignition by wind-driven firebrand showers is an important fire spread mechanism in large outdoor fires. Experiments were conducted with three common mulch types (shredded hardwood mulch, Japanese Cypress wood chips, and pine bark nuggets) placed adjacent to realistic-scale reentrant corners. In the first series of experiments, mulch beds were placed adjacent to a re-entrant corner constructed with wood studs and lined with oriented strand board (OSB) as the sheathing. The premise behind conducting experiments with no siding treatments applied was predicated on the notion that bare OSB mulch contact would be a worst-case scenario, and therefore, a wall assembly in the most vulnerable state to mulch ignition. In the second series of experiments, vinyl siding was applied to the re-entrant corner assemblies (wood studs/OSB/moisture barrier/vinyl siding), and the influence of vertical separation distance (102 mm or 203 mm) on wall ignition from adjacent mulch beds was determined. The vertical separation distance was maintained by applying gypsum board to the base of the re-entrant corner. The siding itself did not influence the ignition process for the mulch beds, as the mulch beds were the first to ignite from the firebrand showers. In all experiments, it was observed that firebrands produced smoldering ignition in the mulch beds, this transitioned to flaming ignition, and the re-entrant corner assembly was exposed to the flaming mulch beds. With no siding treatments applied, the flaming mulch beds ignited the re-entrant corner, and ignition was observed to propagate to the back side of re-entrant corner assembly under all wind speeds (6 m/s to 8 m/s). With respect to the re-entrant corners fitted with vinyl siding, the mulch type, vertical separation distance, and wind speed were important parameters as to whether flaming ignition was observed to propagate to the back-side of a reentrant corner assembly. Mulches clearly pose an ignition hazard to structures in large outdoor fires.

Understanding the ignition mechanism of high-pressure spray flames

DOE PAGES

Dahms, Rainer N.; Paczko, Günter A.; Skeen, Scott A.; ...

2016-10-25

A conceptual model for turbulent ignition in high-pressure spray flames is presented. The model is motivated by first-principles simulations and optical diagnostics applied to the Sandia n-dodecane experiment. The Lagrangian flamelet equations are combined with full LLNL kinetics (2755 species; 11,173 reactions) to resolve all time and length scales and chemical pathways of the ignition process at engine-relevant pressures and turbulence intensities unattainable using classic DNS. The first-principles value of the flamelet equations is established by a novel chemical explosive mode-diffusion time scale analysis of the fully-coupled chemical and turbulent time scales. Contrary to conventional wisdom, this analysis reveals thatmore » the high Damköhler number limit, a key requirement for the validity of the flamelet derivation from the reactive Navier–Stokes equations, applies during the entire ignition process. Corroborating Rayleigh-scattering and formaldehyde PLIF with simultaneous schlieren imaging of mixing and combustion are presented. Our combined analysis establishes a characteristic temporal evolution of the ignition process. First, a localized first-stage ignition event consistently occurs in highest temperature mixture regions. This initiates, owed to the intense scalar dissipation, a turbulent cool flame wave propagating from this ignition spot through the entire flow field. This wave significantly decreases the ignition delay of lower temperature mixture regions in comparison to their homogeneous reference. This explains the experimentally observed formaldehyde formation across the entire spray head prior to high-temperature ignition which consistently occurs first in a broad range of rich mixture regions. There, the combination of first-stage ignition delay, shortened by the cool flame wave, and the subsequent delay until second-stage ignition becomes minimal. A turbulent flame subsequently propagates rapidly through the entire mixture over time scales consistent with experimental observations. As a result, we demonstrate that the neglect of turbulence-chemistry-interactions fundamentally fails to capture the key features of this ignition process.« less

Evaluating temperature and fuel stratification for heat-release rate control in a reactivity-controlled compression-ignition engine using optical diagnostics and chemical kinetics modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musculus, Mark P. B.; Kokjohn, Sage L.; Reitz, Rolf D.

We investigated the combustion process in a dual-fuel, reactivity-controlled compression-ignition (RCCI) engine using a combination of optical diagnostics and chemical kinetics modeling to explain the role of equivalence ratio, temperature, and fuel reactivity stratification for heat-release rate control. An optically accessible engine is operated in the RCCI combustion mode using gasoline primary reference fuels (PRF). A well-mixed charge of iso-octane (PRF = 100) is created by injecting fuel into the engine cylinder during the intake stroke using a gasoline-type direct injector. Later in the cycle, n-heptane (PRF = 0) is delivered through a centrally mounted diesel-type common-rail injector. This injectionmore » strategy generates stratification in equivalence ratio, fuel blend, and temperature. The first part of this study uses a high-speed camera to image the injection events and record high-temperature combustion chemiluminescence. Moreover, the chemiluminescence imaging showed that, at the operating condition studied in the present work, mixtures in the squish region ignite first, and the reaction zone proceeds inward toward the center of the combustion chamber. The second part of this study investigates the charge preparation of the RCCI strategy using planar laser-induced fluorescence (PLIF) of a fuel tracer under non-reacting conditions to quantify fuel concentration distributions prior to ignition. The fuel-tracer PLIF data show that the combustion event proceeds down gradients in the n-heptane distribution. The third part of the study uses chemical kinetics modeling over a range of mixtures spanning the distributions observed from the fuel-tracer fluorescence imaging to isolate the roles of temperature, equivalence ratio, and PRF number stratification. The simulations predict that PRF number stratification is the dominant factor controlling the ignition location and growth rate of the reaction zone. Equivalence ratio has a smaller, but still significant, influence. Lastly, temperature stratification had a negligible influence due to the NTC behavior of the PRF mixtures.« less

Evaluating temperature and fuel stratification for heat-release rate control in a reactivity-controlled compression-ignition engine using optical diagnostics and chemical kinetics modeling

DOE PAGES

Musculus, Mark P. B.; Kokjohn, Sage L.; Reitz, Rolf D.

2015-04-23

We investigated the combustion process in a dual-fuel, reactivity-controlled compression-ignition (RCCI) engine using a combination of optical diagnostics and chemical kinetics modeling to explain the role of equivalence ratio, temperature, and fuel reactivity stratification for heat-release rate control. An optically accessible engine is operated in the RCCI combustion mode using gasoline primary reference fuels (PRF). A well-mixed charge of iso-octane (PRF = 100) is created by injecting fuel into the engine cylinder during the intake stroke using a gasoline-type direct injector. Later in the cycle, n-heptane (PRF = 0) is delivered through a centrally mounted diesel-type common-rail injector. This injectionmore » strategy generates stratification in equivalence ratio, fuel blend, and temperature. The first part of this study uses a high-speed camera to image the injection events and record high-temperature combustion chemiluminescence. Moreover, the chemiluminescence imaging showed that, at the operating condition studied in the present work, mixtures in the squish region ignite first, and the reaction zone proceeds inward toward the center of the combustion chamber. The second part of this study investigates the charge preparation of the RCCI strategy using planar laser-induced fluorescence (PLIF) of a fuel tracer under non-reacting conditions to quantify fuel concentration distributions prior to ignition. The fuel-tracer PLIF data show that the combustion event proceeds down gradients in the n-heptane distribution. The third part of the study uses chemical kinetics modeling over a range of mixtures spanning the distributions observed from the fuel-tracer fluorescence imaging to isolate the roles of temperature, equivalence ratio, and PRF number stratification. The simulations predict that PRF number stratification is the dominant factor controlling the ignition location and growth rate of the reaction zone. Equivalence ratio has a smaller, but still significant, influence. Lastly, temperature stratification had a negligible influence due to the NTC behavior of the PRF mixtures.« less

Space Launch System Scale Model Acoustic Test Ignition Overpressure Testing

NASA Technical Reports Server (NTRS)

Nance, Donald K.; Liever, Peter A.

2015-01-01

The overpressure phenomenon is a transient fluid dynamic event occurring during rocket propulsion system ignition. This phenomenon results from fluid compression of the accelerating plume gas, subsequent rarefaction, and subsequent propagation from the exhaust trench and duct holes. The high-amplitude unsteady fluid-dynamic perturbations can adversely affect the vehicle and surrounding structure. Commonly known as ignition overpressure (IOP), this is an important design-to environment for the Space Launch System (SLS) that NASA is currently developing. Subscale testing is useful in validating and verifying the IOP environment. This was one of the objectives of the Scale Model Acoustic Test (SMAT), conducted at Marshall Space Flight Center (MSFC). The test data quantifies the effectiveness of the SLS IOP suppression system and improves the analytical models used to predict the SLS IOP environments. The reduction and analysis of the data gathered during the SMAT IOP test series requires identification and characterization of multiple dynamic events and scaling of the event waveforms to provide the most accurate comparisons to determine the effectiveness of the IOP suppression systems. The identification and characterization of the overpressure events, the waveform scaling, the computation of the IOP suppression system knockdown factors, and preliminary comparisons to the analytical models are discussed.

High-density carbon (HDC) capsule designs for α-heating and for ignition

NASA Astrophysics Data System (ADS)

Ho, D.; Amendt, A.; Clark, D.; Haan, S.; Milovich, J.; Salmonson, J.; Zimmerman, G.; Berzak Hopkins, L.; Biener, J.; Meezan, N.; Thomas, C.; Benedict, L.; Le Pape, S.; MacKinnon, A.; Ross, S.

2014-10-01

We show capsule designs that have HDC ablators, using 2, 3 and 4 shocks. Their advantages and disadvantages will be discussed. Two-shock designs have the shortest pulse length but have the worst 1-D ignition margin because of the high fuel adiabat. Four-shock designs have the highest 1-D ignition margin with the lowest adiabat, but have higher RT ablation front growth. This disadvantage can be overcome by using a picket to generate the 1st shock. The picket reduces the RT growth factor while the decaying 1st shock lowers the fuel adiabat further. The picket has the additional advantage of shortening the pulse length. Dopant requirements for different hohlraums will be discussed. A 3-shock design for achieving alpha heating is described, which can use either high-gas-fill (1.6 mg/cc) or near-vacuum hohlraums. A rugby-shaped hohlraum with low gas-fill (0.5 mg/cc) has high laser coupling efficiency and provides good symmetry for a 4-shock design. Comparison of simulations for selected recent HDC shots with experimental data will be presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

Space Launch System Scale Model Acoustic Test Ignition Overpressure Testing

NASA Technical Reports Server (NTRS)

Nance, Donald; Liever, Peter; Nielsen, Tanner

2015-01-01

The overpressure phenomenon is a transient fluid dynamic event occurring during rocket propulsion system ignition. This phenomenon results from fluid compression of the accelerating plume gas, subsequent rarefaction, and subsequent propagation from the exhaust trench and duct holes. The high-amplitude unsteady fluid-dynamic perturbations can adversely affect the vehicle and surrounding structure. Commonly known as ignition overpressure (IOP), this is an important design-to environment for the Space Launch System (SLS) that NASA is currently developing. Subscale testing is useful in validating and verifying the IOP environment. This was one of the objectives of the Scale Model Acoustic Test, conducted at Marshall Space Flight Center. The test data quantifies the effectiveness of the SLS IOP suppression system and improves the analytical models used to predict the SLS IOP environments. The reduction and analysis of the data gathered during the SMAT IOP test series requires identification and characterization of multiple dynamic events and scaling of the event waveforms to provide the most accurate comparisons to determine the effectiveness of the IOP suppression systems. The identification and characterization of the overpressure events, the waveform scaling, the computation of the IOP suppression system knockdown factors, and preliminary comparisons to the analytical models are discussed.

Wildfire ignition-distribution modelling: a comparative study in the Huron-Manistee National Forest, Michigan, USA

Treesearch

Avi Bar Massada; Alexandra D. Syphard; Susan I. Stewart; Volker C. Radeloff

2012-01-01

Wildfire ignition distribution models are powerful tools for predicting the probability of ignitions across broad areas, and identifying their drivers. Several approaches have been used for ignition-distribution modelling, yet the performance of different model types has not been compared. This is unfortunate, given that conceptually similar species-distribution models...

77 FR 42724 - Agency Information Collection Activities; Submission to OMB for Review and Approval; Comment...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-20

... Nonroad Spark-Ignited Engines, New Nonroad Compression-Ignited Engines, and New On-Road Heavy Duty Engines... Compression-ignited Engines, and New On-road Heavy Duty Engines (Renewal). ICR numbers: EPA ICR No. 1852.05... engines, new nonroad compression-ignited engines, and new on- road heavy duty engines. Estimated Number of...

16 CFR 1145.3 - Extremely flammable contact adhesives; risk of burns from explosive vapor ignition and flashback...

Code of Federal Regulations, 2014 CFR

2014-01-01

... of burns from explosive vapor ignition and flashback fire. 1145.3 Section 1145.3 Commercial Practices...; risk of burns from explosive vapor ignition and flashback fire. (a) The Commission finds that it is in the public interest to regulate the risk of burns from explosive vapor ignition and flashback fire...

16 CFR 1145.3 - Extremely flammable contact adhesives; risk of burns from explosive vapor ignition and flashback...

Code of Federal Regulations, 2011 CFR

2011-01-01

... of burns from explosive vapor ignition and flashback fire. 1145.3 Section 1145.3 Commercial Practices...; risk of burns from explosive vapor ignition and flashback fire. (a) The Commission finds that it is in the public interest to regulate the risk of burns from explosive vapor ignition and flashback fire...

16 CFR 1145.3 - Extremely flammable contact adhesives; risk of burns from explosive vapor ignition and flashback...

Code of Federal Regulations, 2012 CFR

2012-01-01

... of burns from explosive vapor ignition and flashback fire. 1145.3 Section 1145.3 Commercial Practices...; risk of burns from explosive vapor ignition and flashback fire. (a) The Commission finds that it is in the public interest to regulate the risk of burns from explosive vapor ignition and flashback fire...

16 CFR 1145.3 - Extremely flammable contact adhesives; risk of burns from explosive vapor ignition and flashback...

Code of Federal Regulations, 2010 CFR

2010-01-01

... of burns from explosive vapor ignition and flashback fire. 1145.3 Section 1145.3 Commercial Practices...; risk of burns from explosive vapor ignition and flashback fire. (a) The Commission finds that it is in the public interest to regulate the risk of burns from explosive vapor ignition and flashback fire...

Ignition in tokamaks with modulated source of auxiliary heating

NASA Astrophysics Data System (ADS)

Morozov, D. Kh

2017-12-01

It is shown that the ignition may be achieved in tokamaks with the modulated power source. The time-averaged source power may be smaller than the steady-state source power, which is sufficient for the ignition. Nevertheless, the maximal power must be large enough, because the ignition must be achieved within a finite time interval.

Geomorphic aspects of post-fire soil erosion - Schultz Fire 2010

Treesearch

Ann Youberg; Karen A. Koestner; Daniel G. Neary; Peter E. Koestner

2011-01-01

The summer of 2010 brought wildfires and near record monsoon rains to northern Arizona, USA, which generated debris flows and floods that caused extensive damage. The human-caused Schultz Fire on the Coconino National Forest northeast of Flagstaff was the largest wildfire in Arizona during 2010, burning 6,100 ha between June 20th and 30th. Ignited by an abandoned...

Locating spatial variation in the association between wildland fire risk and social vulnerability across six southern states

Treesearch

Neelam Poudyal; Cassandra Johnson Gaither; Scott Goodrick; J.M. Bowker; Jianbang Gan

2012-01-01

Wildland fire in the South commands considerable attention, given the expanding wildland urban interface (WUI) across the region. Much of this growth is propelled by higher income retirees and others desiring natural amenity residential settings. However, population growth in the WUI increases the likelihood of wildfire fire ignition caused by people, as humans account...

Emotion as the Amplifier and the Primary Motive: Some Theories of Emotion with Relevance to Language Learning

ERIC Educational Resources Information Center

Oxford, Rebecca L.

2015-01-01

Emotion is crucial to living and learning. The powerful intertwining of emotion and cognition ignites learning within a complex dynamic system, which, as several sections of this paper show, also includes societal and cultural influences. As "the primary human motive" (MacIntyre, 2002a, p. 61), emotion operates as an amplifier, which…

LOx / LCH4: A Unifying Technology for Future Exploration

NASA Technical Reports Server (NTRS)

Falker, John; Terrier, Douglas; Clayton, Ronald G.; Banker, Brian; Ryan, Abigail

2015-01-01

Reduced mass due to increasing commonality between spacecraft subsystems such as power and propulsion have been identified as critical to enabling human missions to Mars. This project represents the first ever integrated propulsion and power system testing and lays the foundations for future sounding rocket flight testing, which will yield the first in-space ignition of a LOx / LCH4 rocket engine.

Fuels planning: Managing forest structure to reduce fire hazard

Treesearch

David L. Peterson; Morris C. Johnson; James K. Agee; Theresa B. Jain; Donald McKenzie; Elizabeth D. Reinhardt

2003-01-01

Prior to the 20th century, low intensity fires burned regularly in most arid to semiarid forest ecosystems, with ignitions caused by lightning and humans (e.g., Baisan and Swetnam 1997, Allen et al. 2002, Hessl et al. 2004). Low intensity fires controlled regeneration of fire sensitive (e.g., grand fir [Abies grandis]) species (Arno and Allison-Bunnell 2002), promoted...

Thermal remote sensing of active vegetation fires and biomass burning events [Chapter 18

Treesearch

Martin J. Wooster; Gareth Roberts; Alistair M.S. Smith; Joshua Johnston; Patrick Freeborn; Stefania Amici; Andrew T. Hudak

2013-01-01

Thermal remote sensing is widely used in the detection, study, and management of biomass burning occurring in open vegetation fires. Such fires may be planned for land management purposes, may occur as a result of a malicious or accidental ignition by humans, or may result from lightning or other natural phenomena. Under suitable conditions, fires may spread rapidly...

An Ignition Torch Based on Photoignition of Carbon Nanotubes at Elevated Pressure (Briefing Charts)

DTIC Science & Technology

2016-01-04

Ignition Capsule A 10 mg low pressure ignition torch as it ignites a fuel spray We use PITCH to ignite subscale test rockets at 130 K and ~35 atm (~500...distribution is unlimited High Pressure PITCH Applied to a H2/O2 Subscale Rocket Injector Top: a high-pressure chamber for test of subscale rocket injector...to a high-pressure test combustion chamber via a 20 cm extension tube (OD=6 mm) Click >>> 9 DISTRIBUTION STATEMENT A. Approved for public release

Electron Shock Ignition of Inertial Fusion Targets

DOE PAGES

Shang, W. L.; Betti, R.; Hu, S. X.; ...

2017-11-07

Here, it is shown that inertial fusion targets designed with low implosion velocities can be shock ignited using laser–plasma interaction generated hot electrons (hot-e) to obtain high-energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e, which can only be produced on a large laser facility like the National Ignition Facility, with the laser to hot-e conversion efficiency greater than 10% at laser intensities ~10 16 W/cm 2.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swain, M.R.

The following report is divided into two sections. The first section describes the results of ignitability tests of high pressure hydrogen and natural gas leaks. The volume of ignitable gases formed by leaking hydrogen or natural gas were measured. Leaking high pressure hydrogen produced a cone of ignitable gases with 28{degrees} included angle. Leaking high pressure methane produced a cone of ignitable gases with 20{degrees} included angle. Ignition of hydrogen produced larger overpressures than did natural gas. The largest overpressures produced by hydrogen were the same as overpressures produced by inflating a 11 inch child`s balloon until it burst.

Electron Shock Ignition of Inertial Fusion Targets

NASA Astrophysics Data System (ADS)

Shang, W. L.; Betti, R.; Hu, S. X.; Woo, K.; Hao, L.; Ren, C.; Christopherson, A. R.; Bose, A.; Theobald, W.

2017-11-01

It is shown that inertial confinement fusion targets designed with low implosion velocities can be shock-ignited using laser-plasma interaction generated hot electrons (hot-e 's) to obtain high energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e 's which can be produced only at a large laser facility like the National Ignition Facility, with the laser-to-hot-e conversion efficiency greater than 10% at laser intensities ˜1016 W /cm2 .

Electron Shock Ignition of Inertial Fusion Targets.

PubMed

Shang, W L; Betti, R; Hu, S X; Woo, K; Hao, L; Ren, C; Christopherson, A R; Bose, A; Theobald, W

2017-11-10

It is shown that inertial confinement fusion targets designed with low implosion velocities can be shock-ignited using laser-plasma interaction generated hot electrons (hot-e's) to obtain high energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e's which can be produced only at a large laser facility like the National Ignition Facility, with the laser-to-hot-e conversion efficiency greater than 10% at laser intensities ∼10^{16}  W/cm^{2}.

Repetitive laser ignition by optical breakdown of a LOX/H2 rocket combustion chamber with multi-injector head configuration

NASA Astrophysics Data System (ADS)

Börner, Michael; Manfletti, Chiara; Kroupa, Gerhard; Oschwald, Michael

2017-09-01

This paper reports on the repetitive laser ignition by optical breakdown within an experimental rocket combustion chamber. Ignition was performed by focusing a laser pulse generated by a miniaturized diode-pumped Nd:YAG laser system. The system, which delivers 33.2 mJ in 2.3 ns, was mounted directly to the combustion chamber. The ignition process and flame stabilization was investigated using an optical probe system monitoring the flame attachment across the 15 coaxial injector configuration. 1195 successful ignitions were performed proving the reliability of this laser ignition system and its applicability to the propellant combination LOX/hydrogen at temperatures of T_{{{H}_{ 2} }} = 120-282 K and T_{{{O}_{ 2} }} = 110-281 K.

Ignition Study on a Rotary-valved Air-breathing Pulse Detonation Engine

NASA Astrophysics Data System (ADS)

Wu, Yuwen; Han, Qixiang; Shen, Yujia; Zhao, Wei

2017-05-01

In the present study, the ignition effect on detonation initiation was investigated in the air-breathing pulse detonation engine. Two kinds of fuel injection and ignition methods were applied. For one method, fuel and air was pre-mixed outside the PDE and then injected into the detonation tube. The droplet sizes of mixtures were measured. An annular cavity was used as the ignition section. For the other method, fuel-air mixtures were mixed inside the PDE, and a pre-combustor was utilized as the ignition source. At firing frequency of 20 Hz, transition to detonation was obtained. Experimental results indicated that the ignition position and initial flame acceleration had important effects on the deflagration-to-detonation transition.

Epidemic History and Iatrogenic Transmission of Blood-borne Viruses in Mid-20th Century Kinshasa.

PubMed

Hogan, Catherine A; Iles, James; Frost, Eric H; Giroux, Geneviève; Cassar, Olivier; Gessain, Antoine; Dion, Marie-Josée; Ilunga, Vicky; Rambaut, Andrew; Yengo-Ki-Ngimbi, André-Édouard; Behets, Frieda; Pybus, Oliver G; Pépin, Jacques

2016-08-01

The human immunodeficiency virus type 1 (HIV-1) pandemic was ignited in Léopoldville (now known as Kinshasa), in the former Belgian Congo. Factors that jump-started its early expansion remain unclear. Nonlethal hepatitis C virus (HCV) and human T-cell lymphotropic virus (HTLV-1) can be used to investigate past iatrogenic transmission. We undertook a cross-sectional study of elderly inhabitants of Kinshasa, with serological assays, amplification, and sequencing. Risk factors were assessed through logistic regression. Phylogenetic methods reconstructed the genetic history of HCV. A total of 217 of 839 participants (25.9%) were HCV seropositive; 26 (3.1%) were HTLV-1-seropositive. Amplification products were obtained from 118 HCV-seropositive participants; subtypes 4k (in 47 participants) and 4r (in 38) were most common. Independent risk factors for HCV subtype 4r seropositivity were intramuscular tuberculosis therapy, intravenous injections at hospital A, intravenous injections before 1960, and injections at a colonial-era venereology clinic. Intravenous injections at hospital B and antimalarials were associated with HCV subtype 4k seropositivity. Risk factors for HTLV-1 seropositivity included intravenous injections at hospitals C or D and transfusions. Evolutionary analysis of viral sequences revealed independent exponential amplification of HCV subtypes 4r and 4k from the 1950s onward. Iatrogenic transmission of HCV and HTLV-1 occurred in mid-20th century Kinshasa, at the same time and place HIV-1 emerged. Iatrogenic routes may have contributed to the early establishment of the pandemic. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Improved Photo-Ignition of Carbon Nanotubes/Ferrocene Using a Lipophilic Porphyrin under White Power LED Irradiation

PubMed Central

Primiceri, Patrizio; de Fazio, Roberto; Carlucci, Antonio Paolo; Mazzetto, Selma Elaine

2018-01-01

The aim of this work is to investigate and characterize the photo-ignition process of dry multi-walled carbon nanotubes (MWCNTs) mixed with ferrocene (FeCp2) powder, using an LED (light-emitting diode) as the light source, a combination that has never been used, to the best of our knowledge. The ignition process was improved by adding a lipophilic porphyrin (H2Pp) in powder to the MWCNTs/FeCp2 mixtures—thus, a lower ignition threshold was obtained. The ignition tests were carried out by employing a continuous emission and a pulsed white LED in two test campaigns. In the first, two MWCNT typologies, high purity (HP) and industrial grade (IG), were used without porphyrin, obtaining, for both, similar ignition thresholds. Furthermore, comparing ignition thresholds obtained with the LED source with those previously obtained with a Xenon (Xe) lamp, a significant reduction was observed. In the second test campaign, ignition tests were carried out by means of a properly driven and controlled pulsed XHP70 LED source. The minimum ignition energy (MIE) of IG-MWCNTs/FeCp2 samples was determined by varying the duration of the light pulse. Experimental results show that ignition is obtained with a pulse duration of 110 ms and a MIE density of 266 mJ/cm2. The significant reduction of the MIE value (10–40%), observed when H2Pp in powder form was added to the MWCNTs/FeCp2 mixtures, was ascribed to the improved photoexcitation and charge transfer properties of the lipophilic porphyrin molecules. PMID:29342878

Laser Ignition Technology for Bi-Propellant Rocket Engine Applications

NASA Technical Reports Server (NTRS)

Thomas, Matthew E.; Bossard, John A.; Early, Jim; Trinh, Huu; Dennis, Jay; Turner, James (Technical Monitor)

2001-01-01

The fiber optically coupled laser ignition approach summarized is under consideration for use in igniting bi-propellant rocket thrust chambers. This laser ignition approach is based on a novel dual pulse format capable of effectively increasing laser generated plasma life times up to 1000 % over conventional laser ignition methods. In the dual-pulse format tinder consideration here an initial laser pulse is used to generate a small plasma kernel. A second laser pulse that effectively irradiates the plasma kernel follows this pulse. Energy transfer into the kernel is much more efficient because of its absorption characteristics thereby allowing the kernel to develop into a much more effective ignition source for subsequent combustion processes. In this research effort both single and dual-pulse formats were evaluated in a small testbed rocket thrust chamber. The rocket chamber was designed to evaluate several bipropellant combinations. Optical access to the chamber was provided through small sapphire windows. Test results from gaseous oxygen (GOx) and RP-1 propellants are presented here. Several variables were evaluated during the test program, including spark location, pulse timing, and relative pulse energy. These variables were evaluated in an effort to identify the conditions in which laser ignition of bi-propellants is feasible. Preliminary results and analysis indicate that this laser ignition approach may provide superior ignition performance relative to squib and torch igniters, while simultaneously eliminating some of the logistical issues associated with these systems. Further research focused on enhancing the system robustness, multiplexing, and window durability/cleaning and fiber optic enhancements is in progress.

Improved Photo-Ignition of Carbon Nanotubes/Ferrocene Using a Lipophilic Porphyrin under White Power LED Irradiation.

PubMed

Visconti, Paolo; Primiceri, Patrizio; de Fazio, Roberto; Carlucci, Antonio Paolo; Mazzetto, Selma Elaine; Mele, Giuseppe

2018-01-13

The aim of this work is to investigate and characterize the photo-ignition process of dry multi-walled carbon nanotubes (MWCNTs) mixed with ferrocene (FeCp₂) powder, using an LED (light-emitting diode) as the light source, a combination that has never been used, to the best of our knowledge. The ignition process was improved by adding a lipophilic porphyrin (H₂Pp) in powder to the MWCNTs/FeCp₂ mixtures-thus, a lower ignition threshold was obtained. The ignition tests were carried out by employing a continuous emission and a pulsed white LED in two test campaigns. In the first, two MWCNT typologies, high purity (HP) and industrial grade (IG), were used without porphyrin, obtaining, for both, similar ignition thresholds. Furthermore, comparing ignition thresholds obtained with the LED source with those previously obtained with a Xenon (Xe) lamp, a significant reduction was observed. In the second test campaign, ignition tests were carried out by means of a properly driven and controlled pulsed XHP70 LED source. The minimum ignition energy (MIE) of IG-MWCNTs/FeCp₂ samples was determined by varying the duration of the light pulse. Experimental results show that ignition is obtained with a pulse duration of 110 ms and a MIE density of 266 mJ/cm². The significant reduction of the MIE value (10-40%), observed when H₂Pp in powder form was added to the MWCNTs/FeCp₂ mixtures, was ascribed to the improved photoexcitation and charge transfer properties of the lipophilic porphyrin molecules.

Crank angle detecting system for engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yuzawa, H.; Nishiyama, M.; Nakamura, K.

1988-05-31

An ignition system for a multi-cylinder internal combustion engine is described comprising: (a) engine cylinders in which spark plugs are installed respectively, (b) indicating means disposed so as to synchronize with an engine crankshaft and formed with a large number of slits and a small number of slits, the large number of slits being provided for indicating crankshaft angular positions and the small number of slits being provided for indicating predetermined piston strokes and wherein the small number of slits have mutually different widths from each other to distinguish between piston strokes of at least the groups of cylinders; (c)more » sensing means for sensing crankshaft angular positions in cooperation with the large number of slits of the indicating means and outputting a crank angle signal representing the crankshaft angular position and for sensing the predetermined piston strokes in cooperation with the small number of slits and outputting different width piston stroke signals corresponding to the different width slits; (d) discriminating means for identifying each cylinder group and outputting cylinder group identification signals on the basis of the different width stroke signals derived from the sensing means; (e) ignition timing determining means for generating an ignition timing signal on the basis of the crank angle signal; (f) ignition coil controlling means for generating ignition coil current signals corresponding to the cylinder group identification signals; and (g) ignition timing controlling means for generating cylinder group ignition signals in response to the ignition coil current signals and ignition timing signal so that the spark plugs of each cylinder group are ignited at a proper time.« less

Definition of Ignition in Inertial Confinement Fusion

NASA Astrophysics Data System (ADS)

Christopherson, A. R.; Betti, R.

2017-10-01

Defining ignition in inertial confinement fusion (ICF) is an unresolved problem. In ICF, a distinction must be made between the ignition of the hot spot and the propagation of the burn wave in the surrounding dense fuel. Burn propagation requires that the hot spot is robustly ignited and the dense shell exhibits enough areal density. Since most of the energy gain comes from burning the dense shell, in a scale of increasing yields, hot-spot ignition comes before high gains. Identifying this transition from hot-spot ignition to burn-wave propagation is key to defining ignition in general terms applicable to all fusion approaches that use solid DT fuel. Ad hoc definitions such as gain = 1 or doubling the temperature are not generally valid. In this work, we show that it is possible to identify the onset of ignition through a unique value of the yield amplification defined as the ratio of the fusion yield including alpha-particle deposition to the fusion yield without alphas. Since the yield amplification is a function of the fractional alpha energy fα =EαEα 2Ehs 2Ehs (a measurable quantity), it appears possible not only to define ignition but also to measure the onset of ignition by the experimental inference of the fractional alpha energy and yield amplification. This material is based upon work supported by the Department of Energy Office of Fusion Energy Services under Award Number DE-FC02-04ER54789 and National Nuclear Security Administration under Award Number DE-NA0001944.

Ignition and combustion of bulk metals at normal, elevated and reduced gravity

NASA Technical Reports Server (NTRS)

Branch, Melvyn C.; Daily, John W.; Abbud-Madrid, Angel

1995-01-01

Knowledge of the oxidation, ignition, and combustion of bulk metals is important for fire safety in the production, management, and utilization of liquid and gaseous oxygen for ground based and space applications. This proposal outlines studies in continuation of research initiated earlier under NASA support to investigate the ignition and combustion characteristics of bulk metals under varying gravity conditions. Metal ignition and combustion have not been studied previously under these conditions and the results are important not only for improved fire safety but also to increase knowledge of basic ignition and combustion mechanisms. The studies completed to date have led to the development of a clean and reproducible ignition source and diagnostic techniques for combustion measurements and have provided normal, elevated, and reduced gravity combustion data on a variety of different pure metals. The research conducted under this grant will use the apparatus and techniques developed earlier to continue the elevated and low gravity experiments, and to develop the overall modeling of the ignition and combustion process. Metal specimens are to be ignited using a xenon short-arc lamp and measurements are to be made of the ignition energy, surface temperature history, burning rates, spectroscopy of surface and gas products, and surface morphology and chemistry. Elevated gravity will be provided by the University of Colorado Geotechnical Centrifuge and microgravity will be obtained in NASA's DC-9 Reduced Gravity aircraft.

Test methods for determining the suitability of metal alloys for use in oxygen-enriched environments

NASA Technical Reports Server (NTRS)

Stoltzfus, Joel M.; Gunaji, Mohan V.

1991-01-01

Materials are more flammable in oxygen rich environments than in air. When the structural elements of a system containing oxygen ignite and burn, the results are often catastrophic, causing loss of equipment and perhaps even human lives. Therefore, selection of the proper metallic and non-metallic materials for use in oxygen systems is extremely important. While test methods for the selection of non-metallic materials have been available for years, test methods for the selection of alloys have not been available until recently. Presented here are several test methods that were developed recently at NASA's White Sands Test Facility (WSTF) to study the ignition and combustion of alloys, including the supersonic and subsonic speed particle impact tests, the frictional heating and coefficient of friction tests, and the promoted combustion test. These test methods are available for commercial use.

16 CFR § 1145.3 - Extremely flammable contact adhesives; risk of burns from explosive vapor ignition and flashback...

Code of Federal Regulations, 2013 CFR

2013-01-01

... of burns from explosive vapor ignition and flashback fire. § 1145.3 Section § 1145.3 Commercial...; risk of burns from explosive vapor ignition and flashback fire. (a) The Commission finds that it is in the public interest to regulate the risk of burns from explosive vapor ignition and flashback fire...

Hydrogen and Ethene Plasma Assisted Ignition by NS discharge at Elevated Temperatures

NASA Astrophysics Data System (ADS)

Starikovskiy, Andrey

2015-09-01

The kinetics of ignition in lean H2:O2:Ar and C2H4:O2:Ar mixtures has been studied experimentally and numerically after a high-voltage nanosecond discharge. The ignition delay time behind a reflected shock wave was measured with and without the discharge. It was shown that the initiation of the discharge with a specific deposited energy of 10 - 30 mJ/cm3 leads to an order of magnitude decrease in the ignition delay time. Discharge processes and following chain chemical reactions with energy release were simulated. The generation of atoms, radicals and excited and charged particles was numerically simulated using the measured time - resolved discharge current and electric field in the discharge phase. The calculated densities of the active particles were used as input data to simulate plasma-assisted ignition. Good agreement was obtained between the calculated ignition delay times and the experimental data. It follows from the analysis of the calculated results that the main mechanism of the effect of gas discharge on the ignition of hydrocarbons is the electron impact dissociation of O2 molecules in the discharge phase. Detailed kinetic mechanism for plasma assisted ignition of hydrogen and ethene is elaborated and verified.

Ignition dynamics and activation energies of metallic thermites: From nano- to micron-scale particulate composites

NASA Astrophysics Data System (ADS)

Hunt, Emily M.; Pantoya, Michelle L.

2005-08-01

Ignition behaviors associated with nano- and micron-scale particulate composite thermites were studied experimentally and modeled theoretically. The experimental analysis utilized a CO2 laser ignition apparatus to ignite the front surface of compacted nickel (Ni) and aluminum (Al) pellets at varying heating rates. Ignition delay time and ignition temperature as a function of both Ni and Al particle size were measured using high-speed imaging and microthermocouples. The apparent activation energy was determined from this data using a Kissinger isoconversion method. This study shows that the activation energy is significantly lower for nano- compared with micron-scale particulate media (i.e., as low as 17.4 compared with 162.5kJ /mol, respectively). Two separate Arrhenius-type mathematical models were developed that describe ignition in the nano- and the micron-composite thermites. The micron-composite model is based on a heat balance while the nanocomposite model incorporates the energy of phase transformation in the alumina shell theorized to be an initiating step in the solid-solid diffusion reaction and uniquely appreciable in nanoparticle media. These models were found to describe the ignition of the Ni /Al alloy for a wide range of heating rates.

Characterisation of two-stage ignition in diesel engine-relevant thermochemical conditions using direct numerical simulation

DOE PAGES

Krisman, Alex; Hawkes, Evatt R.; Talei, Mohsen; ...

2016-08-30

With the goal of providing a more detailed fundamental understanding of ignition processes in diesel engines, this study reports analysis of a direct numerical simulation (DNS) database. In the DNS, a pseudo turbulent mixing layer of dimethyl ether (DME) at 400 K and air at 900 K is simulated at a pressure of 40 atmospheres. At these conditions, DME exhibits a two-stage ignition and resides within the negative temperature coefficient (NTC) regime of ignition delay times, similar to diesel fuel. The analysis reveals a complex ignition process with several novel features. Autoignition occurs as a distributed, two-stage event. The high-temperaturemore » stage of ignition establishes edge flames that have a hybrid premixed/autoignition flame structure similar to that previously observed for lifted laminar flames at similar thermochemical conditions. In conclusion, a combustion mode analysis based on key radical species illustrates the multi-stage and multi-mode nature of the ignition process and highlights the substantial modelling challenge presented by diesel combustion.« less

Evaluation of the Revolver Ignition Design at the National Ignition Facility Using Polar-Direct-Drive Illumination

NASA Astrophysics Data System (ADS)

McKenty, P. W.; Collins, T. J. B.; Marozas, J. A.; Campbell, E. M.; Molvig, K.; Schmitt, M.

2017-10-01

The direct-drive ignition design Revolver employs a triple-shell target using a beryllium ablator, a copper driver, and an eventual gold pusher. Symmetric numerical calculations indicate that each of the three shells exhibit low convergence ( 3to 5) resulting in a modest gain (G 4) for 1.7 MJ of incident laser energy. Studies are now underway to evaluate the robustness of this design employing polar direct drive (PDD) at the National Ignition Facility. Integral to these calculations is the leveraging of illumination conditioning afforded by research done to demonstrate ignition for a traditional PDD hot-spot target design. Two-dimensional simulation results, employing nonlocal electron-thermal transport and cross-beam energy transport, will be presented that indicate ignition using PDD. A study of the allowed levels of long-wavelength perturbations (target offset and power imbalance) not precluding ignition will also be examined. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Ignition and combustion of bulk metals in a microgravity environment

NASA Technical Reports Server (NTRS)

Branch, Melvyn C.; Daily, J. W.; Abbud-Madrid, Angel

1994-01-01

Knowledge of the oxidation, ignition, and combustion of bulk metals is important for fire safety in the production, management, and utilization of liquid and gaseous oxygen for ground based and space applications. This report summarizes research under NASA support to investigate the ignition and combustion characteristics of bulk metals under varying gravity conditions. Metal ignition and combustion have not been studied previously under these conditions and the results are important not only for improved fire safety but also to increase knowledge of basic ignition and combustion mechanisms. The studies completed to date have led to the development of a clean and reproducible ignition source and diagnostic techniques for combustion measurements and have provided normal gravity combustion data on ten different pure metals. Metal specimens were ignited using a xenon short-arc lamp and measurements were made of the radiant energy flux, surface temperature history, spectroscopy of surface and gas products, and surface morphology and chemistry. Elevated gravity was provided by the University of Colorado Geotechnical Centrifuge.

Cigarette ignition of soft furnishings: A literature review with commentary

NASA Astrophysics Data System (ADS)

Krasny, John F.

1987-04-01

Literature pertinent to the ignition by smoldering cigarettes of upholstered furniture and mattresses (soft furnishings) was searched through early 1986. This included literature on the smoldering behavior of cigarettes in air; their behavior on a variety of substrates simulating soft furnishings; mechanism of smoldering in substrates; relative cigarette ignition resistance of substrates; and relative propensity of commercial cigarette packings to ignite substrates. According to the reviewed literature, the smoldering behavior of cigarettes on substrates differs from that of cigarettes burning in air: on substrates, cigarette temperatures tend to be lower, and burning rates slower. These differences seem to be larger for substrates which ignite than for those which self-extinguish after the cigarette burns out. The characteristics of soft furnishings which insure resistance to cigarette ignition have been established, but those of cigarettes with low propensity to ignite furnishings have not. No mathematical model has been reported for the interaction of cigarette and substrate, but some empirical data do exist.

On the path to fusion energy

NASA Astrophysics Data System (ADS)

Tabak, M.

2016-10-01

There is a need to develop alternate energy sources in the coming century because fossil fuels will become depleted and their use may lead to global climate change. Inertial fusion can become such an energy source, but significant progress must be made before its promise is realized. The high-density approach to inertial fusion suggested by Nuckolls et al. leads reaction chambers compatible with civilian power production. Methods to achieve the good control of hydrodynamic stability and implosion symmetry required to achieve these high fuel densities will be discussed. Fast Ignition, a technique that achieves fusion ignition by igniting fusion fuel after it is assembled, will be described along with its gain curves. Fusion costs of energy for conventional hotspot ignition will be compared with those of Fast Ignition and their capital costs compared with advanced fission plants. Finally, techniques that may improve possible Fast Ignition gains by an order of magnitude and reduce driver scales by an order of magnitude below conventional ignition requirements are described.

Development and Testing of a Methane/Oxygen Catalytic Microtube Ignition System for Rocket Propulsion

NASA Technical Reports Server (NTRS)

Deans, Matthew

2012-01-01

This study sought to develop a catalytic ignition advanced torch system with a unique catalyst microtube design that could serve as a low energy alternative or redundant system for the ignition of methane and oxygen rockets. Development and testing of iterations of hardware was carried out to create a system that could operate at altitude and produce a torch. A unique design was created that initiated ignition via the catalyst and then propagated into external staged ignition. This system was able to meet the goals of operating across a range of atmospheric and altitude conditions with power inputs on the order of 20 to 30 watts with chamber pressures and mass flow rates typical of comparable ignition systems for a 100 lbf engine.

Ignition, Burning, and Extinction of a Strained Fuel Strip

NASA Technical Reports Server (NTRS)

Selerland, T.; Karagozian, A. R.

1996-01-01

Flame structure and ignition and extinction processes associated with a strained fuel strip are explored numerically using detailed transport and complex kinetics for a propane-air reaction. Ignition modes are identified that are similar to those predicted by one-step activation energy asymptotics, i.e., modes in which diffusion flames can ignite as independent or dependent interfaces, and modes in which single premixed or partially premixed flames ignite. These ignition modes are found to be dependent on critical combinations of strain rate, fuel strip thickness, and initial reactant temperatures. Extinction in this configuration is seen to occur due to fuel consumption by adjacent flames, although viscosity is seen to have the effect of delaying extinction by reducing the effective strain rate and velocity field experienced by the flames.

An Experimental Investigation of Hypergolic Ignition Delay of Hydrogen Peroxide with Fuel Mixtures

NASA Technical Reports Server (NTRS)

Blevins, John A.; Gostowski, Rudy; Chianese, Silvio

2003-01-01

An experimental investigation of hypergolicity and ignition delay of fuel mixtures with hydrogen peroxide is presented. Example results of high speed photography and schleiren from drop tests are shown. Also, a discussion of the sensitivity to experimental parameters such as drop size and subsequent uncertainty considerations of ignition delay results is presented. It is shown that using the described setup on the mixtures presented, the precision uncertainty is on the order of 6% of average ignition delay and 5% of average decomposition delay. This represents sufficient repeatability for first order discrimination of ignition delay for propellant development and screening. Two mixtures, each using commonly available amines and transition metal compounds, are presented as examples that result in ignition delays on the order of 10 milliseconds.

Development and Testing of a Methane/Oxygen Catalytic Microtube Ignition System for Rocket Propulsion

NASA Technical Reports Server (NTRS)

Deans, Matthew C.; Schneider, Steven J.

2012-01-01

This study sought to develop a catalytic ignition advanced torch system with a unique catalyst microtube design that could serve as a low energy alternative or redundant system for the ignition of methane and oxygen rockets. Development and testing of iterations of hardware was carried out to create a system that could operate at altitude and produce a torch. A unique design was created that initiated ignition via the catalyst and then propagated into external staged ignition. This system was able to meet the goals of operating across a range of atmospheric and altitude conditions with power inputs on the order of 20 to 30 watts with chamber pressures and mass flow rates typical of comparable ignition systems for a 100 Ibf engine.

Frictional Ignition Testing of Composite Materials

NASA Technical Reports Server (NTRS)

Peralta, Steve; Rosales, Keisa; Robinson, Michael J.; Stoltzfus, Joel

2006-01-01

The space flight community has been investigating lightweight composite materials for use in propellant tanks for both liquid and gaseous oxygen for space flight vehicles. The use of these materials presents some risks pertaining to ignition and burning hazards in the presence of oxygen. Through hazard analysis process, some ignition mechanisms have been identified as being potentially credible. One of the ignition mechanisms was reciprocal friction; however, test data do not exist that could be used to clear or fail these types of materials as "oxygen compatible" for the reciprocal friction ignition mechanism. Therefore, testing was performed at White Sands Test Facility (WSTF) to provide data to evaluate this ignition mechanism. This paper presents the test system, approach, data results, and findings of the reciprocal friction testing performed on composite sample materials being considered for propellant tanks.

Wildfire contribution to world-wide desertification.

NASA Astrophysics Data System (ADS)

Neary, D.; Wittenberg, L.; Bautista, S.; Ffolliott, P.

2009-04-01

Wildfire is a natural phenomenon that began with the development of terrestrial vegetation in a lightning-filled atmosphere. Sediments from the Carboniferous Period (307-359 million years before the present) contain evidence of charcoal from post-fire ash slurry flows. As human populations developed in the Pleistocene and Holocene epochs, mankind transformed fire into one of its oldest tools. Human and natural ignited fires from lightning altered and steered the trajectories of ecosystem development in most parts of the world. Humans are now the primary source of forest and grass fire ignitions throughout the world. As human populations have increased and industrialized in the past two centuries, fire ignitions and burned areas have increased due to both sheer numbers of people and anthropogenic changes in the global climate. Recent scientific findings have bolstered the hypothesis that climate change is resulting in fire seasons starting earlier, lasting longer, burning greater areas, and being more severe Computer models point to the Western U.S., Mediterranean nations and Brazil as "hot spots" that will get extremes at their worst. The climatic change to drier and warmer conditions has the potential to aggravate wildfire conditions, resulting in burning over longer seasons, larger areas of vegetation conflagration, and higher fire severities. Wildfire is now driving desertification in some of the forest lands in the western United States. The areas of wildfire in the Southwest USA have increased dramatically in the past two decades from <10,000 ha yr-1 in the early 20th Century to over 230,000 ha yr-1 in the first decade of the 21st Century. Individual wildfires are now larger and produce higher severity burns than in the past. A combination of natural drought, climate change, excessive fuel loads, and increased ignition sources have produced the perfect conditions for fire-induced desertification. Portugal suffered the worst and second worst wildfire seasons in a three-year period (2003 - 2005). In 2005, 338,262 ha of forest land burned. This was a 77% increase over the 10-year burn average of 189,500 ha. Desertification is about the loss of the land's proper hydrologic function, biological productivity, and other ecosystem services as a result of human activities and climate change. It affects one third of the earth's surface and over a billion people. In the past, desertification was considered a problem of only arid, semi-arid, and dry sub-humid areas. However, humid zones can undergo desertification with the wrong combination of human impacts. The Amazon region is an example of where forest harvesting, shifting cut and burn agriculture, and large-scale grazing are producing desertification of a tropical rain forest on a large scale. Some of the environmental consequences of wildfires are vegetation destruction, plant species and type shifts, exotic plant invasions, wildlife habitat destruction, soil erosion, floods, watershed function decline, water supply disruption, and air pollution. All of these are immediate impacts. Some impacts will persist beyond the careers and lifetimes of individuals. Small, isolated areas do not produce noticeable desertification. But, the cumulative effect of multiple, large area, and adjacent fires can be landscape-level desertification. This paper examines wildfire contributions to desertification in regions of the world that are prone to wildfire and climate change.

The Effects of Metallized Fuel Composition on the Combustion Characteristics of Solid Fuel Ramjets

DTIC Science & Technology

1986-12-01

Heater. convening nozzle. As the air was passing through the choked flow nozzle, P r and T t were meassured . Using these measurements the computation of...4 1.12 30 .22 -/- No ignition 4 0.95 43 .20 -/100 1106 Ignition and sustain NWC-5 4 0.95 45 .20 -/67 1052 Ignition. Hard to sustain. NWC-6 1 0.95 52...NUMBER REF. # TABLE 5 in ONLY psia lbm IGNIT./SUST. psia °Rs-in 2 0.95 41 .20 -/75 1125 Ignition. Hard to sustain. NWC-11 3 0.75 62 .20 -/140 1055 Good

Effect of Oxygen Concentration on Autogenous Ignition Temperature and Pneumatic Impact Ignitability of Nonmetallic Materials

NASA Technical Reports Server (NTRS)

Smith, Sarah

2009-01-01

Extensive test data exist on the ignitability of nonmetallic materials in pure oxygen, but these characteristics are not as well understood for lesser oxygen concentrations. In this study, autogenous ignition temperature testing and pneumatic impact testing were used to better understand the effects of oxygen concentration on ignition of nonmetallic materials. Tests were performed using oxygen concentrations of 21, 34, 45, and 100 %. The following materials were tested: PTFE Teflon(Registered Trademark), Buna-N, Silicone, Zytel(Registered Trademark) 42, Viton(registered Trademark) A, and Vespel(Registered Trademark) SP-21.

Mars in situ propellants: Carbon monoxide and oxygen ignition experiments

NASA Technical Reports Server (NTRS)

Linne, Diane L.; Roncace, James; Groth, Mary F.

1990-01-01

Carbon monoxide and oxygen were tested in a standard spark-torch igniter to identify the ignition characteristics of this potential Mars in situ propellant combination. The ignition profiles were determined as functions of mixture ratio, amount of hydrogen added to the carbon monoxide, and oxygen inlet temperature. The experiments indicated that the carbon monoxide and oxygen combination must have small amounts of hydrogen present to initiate reaction. Once the reaction was started, the combustion continued without the presence of hydrogen. A mixture ratio range was identified where ignition occurred, and this range varied with the oxygen inlet temperature.

Microwave-assisted ignition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bechtold, J.K.; Booty, M.R.; Kriegsmann, G.A.

1996-12-31

In recent years, microwave heating has been proposed as an alternative to ignite materials during the process of self-propagating high-temperature synthesis. The microwave heating and ignition of a combustible material is modeled and analyzed in the small Biot number and large activation energy regimes. Both the temporal and spatial evolution of the temperature within the material are described. The ignition characteristics are determined by a localized equation for the perturbation to the inert temperature, which is shown to exhibit thermal runaway behavior. Analysis of this local equation provides explicit ignition conditions in terms of the physical parameters in the problem.

Machining of Two-Dimensional Sinusoidal Defects on Ignition-Type Capsules to Study Hydrodynamic Instability at the National Ignition Facility

DOE PAGES

Giraldez, E. M.; Hoppe Jr., M. L.; Hoover, D. E.; ...

2016-07-07

Hydrodynamic instability growth and its effects on capsule implosion performance are being studied at the National Ignition Facility (NIF). Experimental results have shown that low-mode instabilities are the primary culprit for yield degradation. Ignition type capsules with machined 2D sinusoidal defects were used to measure low-mode hydrodynamic instability growth in the acceleration phase of the capsule implosion. The capsules were imploded using ignition-relevant laser pulses and the ablation-front modulation growth was measured using x-ray radiography. The experimentally measured growth was in good agreement with simulations.

Modeling of Transient Flow Mixing of Streams Injected into a Mixing Chamber

NASA Technical Reports Server (NTRS)

Voytovych, Dmytro M.; Merkle, Charles L.; Lucht, Robert P.; Hulka, James R.; Jones, Gregg W.

2006-01-01

Ignition is recognized as one the critical drivers in the reliability of multiple-start rocket engines. Residual combustion products from previous engine operation can condense on valves and related structures thereby creating difficulties for subsequent starting procedures. Alternative ignition methods that require fewer valves can mitigate the valve reliability problem, but require improved understanding of the spatial and temporal propellant distribution in the pre-ignition chamber. Current design tools based mainly on one-dimensional analysis and empirical models cannot predict local details of the injection and ignition processes. The goal of this work is to evaluate the capability of the modern computational fluid dynamics (CFD) tools in predicting the transient flow mixing in pre-ignition environment by comparing the results with the experimental data. This study is a part of a program to improve analytical methods and methodologies to analyze reliability and durability of combustion devices. In the present paper we describe a series of detailed computational simulations of the unsteady mixing events as the cold propellants are first introduced into the chamber as a first step in providing this necessary environmental description. The present computational modeling represents a complement to parallel experimental simulations' and includes comparisons with experimental results from that effort. A large number of rocket engine ignition studies has been previously reported. Here we limit our discussion to the work discussed in Refs. 2, 3 and 4 which is both similar to and different from the present approach. The similarities arise from the fact that both efforts involve detailed experimental/computational simulations of the ignition problem. The differences arise from the underlying philosophy of the two endeavors. The approach in Refs. 2 to 4 is a classical ignition study in which the focus is on the response of a propellant mixture to an ignition source, with emphasis on the level of energy needed for ignition and the ensuing flame propagation issues. Our focus in the present paper is on identifying the unsteady mixing processes that provide the propellant mixture in which the ignition source is to be placed. In particular, we wish to characterize the spatial and temporal mixture distribution with a view toward identifying preferred spatial and temporal locations for the ignition source. As such, the present work is limited to cold flow (pre-ignition) conditions

40 CFR Table 1b to Subpart Zzzz of... - Operating Limitations for Existing, New, and Reconstructed Spark Ignition 4SRB Stationary RICE...

Code of Federal Regulations, 2012 CFR

2012-07-01

..., and Reconstructed Spark Ignition 4SRB Stationary RICE >500 HP Located at a Major Source of HAP Emissions and Existing Spark Ignition 4SRB Stationary RICE >500 HP Located at an Area Source of HAP... Limitations for Existing, New, and Reconstructed Spark Ignition 4SRB Stationary RICE >500 HP Located at a...

40 CFR Table 1b to Subpart Zzzz of... - Operating Limitations for Existing, New, and Reconstructed Spark Ignition 4SRB Stationary RICE...

Code of Federal Regulations, 2011 CFR

2011-07-01

..., New, and Reconstructed Spark Ignition 4SRB Stationary RICE >500 HP Located at a Major Source of HAP Emissions and Existing Spark Ignition 4SRB Stationary RICE >500 HP Located at an Area Source of HAP... Limitations for Existing, New, and Reconstructed Spark Ignition 4SRB Stationary RICE >500 HP Located at a...

Photoignition Torch Applied to Cryogenic H2/O2 Coaxial Jet

DTIC Science & Technology

2016-12-06

suitable for certain thrusters and liquid rocket engines. This ignition system is scalable for applications in different combustion chambers such as gas ...turbines, gas generators, liquid rocket engines, and multi grain solid rocket motors. photoignition, fuel spray ignition, high pressure ignition...thrusters and liquid rocket engines. This ignition system is scalable for applications in different combustion chambers such as gas turbines, gas

Full-Scale Experimental Investigation to Quantify Building Component Ignition Vulnerability from Mulch Beds Attacked by Firebrand Showers

PubMed Central

Manzello, Samuel L.; Suzuki, Sayaka; Nii, Daisaku

2015-01-01

Structure ignition by wind-driven firebrand showers is an important fire spread mechanism in large outdoor fires. Experiments were conducted with three common mulch types (shredded hardwood mulch, Japanese Cypress wood chips, and pine bark nuggets) placed adjacent to realistic-scale reentrant corners. In the first series of experiments, mulch beds were placed adjacent to a re-entrant corner constructed with wood studs and lined with oriented strand board (OSB) as the sheathing. The premise behind conducting experiments with no siding treatments applied was predicated on the notion that bare OSB mulch contact would be a worst-case scenario, and therefore, a wall assembly in the most vulnerable state to mulch ignition. In the second series of experiments, vinyl siding was applied to the re-entrant corner assemblies (wood studs/OSB/moisture barrier/vinyl siding), and the influence of vertical separation distance (102 mm or 203 mm) on wall ignition from adjacent mulch beds was determined. The vertical separation distance was maintained by applying gypsum board to the base of the re-entrant corner. The siding itself did not influence the ignition process for the mulch beds, as the mulch beds were the first to ignite from the firebrand showers. In all experiments, it was observed that firebrands produced smoldering ignition in the mulch beds, this transitioned to flaming ignition, and the re-entrant corner assembly was exposed to the flaming mulch beds. With no siding treatments applied, the flaming mulch beds ignited the re-entrant corner, and ignition was observed to propagate to the back side of re-entrant corner assembly under all wind speeds (6 m/s to 8 m/s). With respect to the re-entrant corners fitted with vinyl siding, the mulch type, vertical separation distance, and wind speed were important parameters as to whether flaming ignition was observed to propagate to the back-side of a reentrant corner assembly. Mulches clearly pose an ignition hazard to structures in large outdoor fires. PMID:28184098

Assessing and ranking the flammability of some ornamental plant species to select firewise plants for landscaping in WUI (SE France).

NASA Astrophysics Data System (ADS)

Ganteaume, A.; Jappiot, M.; Lampin, C.

2012-04-01

The increasing urbanization of Wildland-Urban Interfaces (WUI) as well as the high fire occurrence in these areas requires the assessment and the ranking of the flammability of the ornamental vegetation surrounding houses especially that planted in hedges. Thus, the flammability of seven species, among those most frequently planted in hedges in Provence (South-Eastern France), were studied at particle level and at dead surface fuel level (litters) under laboratory conditions. The flammability parameters (ignition frequency, time-to-ignition, flaming duration) of the very fine particles (live leaves and particles <2 mm in diameter) were measured using an epiradiator as burning device. The flammability parameters (ignition frequency, time-to-ignition, flaming duration and initial flame propagation) of the undisturbed litter samples were recorded during burning experiments performed on fire bench. Burning experiments using the epiradiator showed that live leaves of Phyllostachys sp., Photinia frasei and Prunus laurocerasus had the shortest time-to-ignition and the highest ignition frequency and flaming duration whereas Pittosporum tobira and Nerium oleander were the longest to ignite with a low frequency. Phyllostachys sp. and Nerium oleander litters were the shortest to ignite while Prunus laurocerasus litter had the lowest bulk density and long time-to-ignition, but high flame propagation. Photinia fraseri litter ignited frequently and had a high flame spread while Pittosporum tobira litter ignited the least frequently and for the shortest duration. Cupressus sempervirens litter had the highest bulk density and the longest flaming duration but the lowest flame propagation. Pyracantha coccinea litter was the longest to ignite and flame propagation was low but lasted a long time. Hierarchical cluster analysis performed on the flammability parameters of live leaves and of litters ranked the seven species in four distinct clusters from the most flammable (Prunus laurocerasus and Pyracantha coccinea) to the least flammable (Pittosporum tobira and Nerium oleander); the other species displaying two groups of intermediate flammabilities (Phyllostachys sp.- Photinia fraseri and Cupressus sempervirens ). The species with highly flammable characteristics should not be used in hedges planted in WUIs in South-Eastern France.

Climatic and weather factors affecting fire occurrence and behavior

Treesearch

Randall P. Benson; John O. Roads; David R. Weise

2009-01-01

Weather and climate have a profound influence on wildland fire ignition potential, fire behavior, and fire severity. Local weather and climate are affected by large-scale patterns of winds over the hemispheres that predispose wildland fuels to fire. The characteristics of wildland fuels, especially the moisture content, ultimately determine fire behavior and the impact...

Biomass consumption during prescribed fires in big sagebrush ecosystems

Treesearch

Clinton S. Wright; Susan J. Prichard

2006-01-01

Big sagebrush (Artemisia tridentata) ecosystems typically experience stand replacing fires during which some or all of the ignited biomass is consumed. Biomass consumption is directly related to the energy released during a fire, and is an important factor that determines smoke production and the effects of fire on other resources. Consumption of...

Upland Oak Ecology and Management

Treesearch

D.H. Van Lear

2004-01-01

Of the many disturbance factors that shaped hardwood forests in the eastern United States, fire was perhaps the most important. Fires ignited by Native Americans and lightning played a dominant role in sustaining oak (Quercus spp.) forests throughout the Central Hardwood Region. Prior to logging at the turn of the last century, fires in the region...

Transport and spatial energy deposition of relativistic electrons in copper-doped fast ignition plasmas

DOE PAGES

Jarrott, L. C.; McGuffey, C.; Beg, F. N.; ...

2017-10-24

Fast electron transport and spatial energy deposition are investigated in integrated cone-guided Fast Ignition experiments by measuring fast electron induced copper K-shell emission using a copper tracer added to deuterated plastic shells with a geometrically reentrant gold cone. Experiments were carried out at the Laboratory for Laser Energetics on the OMEGA/OMEGA-EP Laser where the plastic shells were imploded using 54 of the 60 OMEGA60 beams (3ω, 20 kJ), while the high intensity OMEGA-EP (BL2) beam (1 ω, 10 ps, 500 J, I peak > 10 19 W/cm 2) was focused onto the inner cone tip. Here, a retrograde analysis usingmore » the hybrid-PIC electron transport code, ZUMA, is performed to examine the sensitivity of the copper Kα spatial profile on the laser-produced fast electrons, facilitating the optimization of new target point designs and laser configurations to improve the compressed core areal density by a factor of 4 and the fast electron energy coupling by a factor of 3.5.« less

Direct electrical arc ignition of hybrid rocket motors

NASA Astrophysics Data System (ADS)

Judson, Michael I., Jr.

Hybrid rockets motors provide distinct safety advantages when compared to traditional liquid or solid propellant systems, due to the inherent stability and relative inertness of the propellants prior to established combustion. As a result of this inherent propellant stability, hybrid motors have historically proven difficult to ignite. State of the art hybrid igniter designs continue to require solid or liquid reactants distinct from the main propellants. These ignition methods however, reintroduce to the hybrid propulsion system the safety and complexity disadvantages associated with traditional liquid or solid propellants. The results of this study demonstrate the feasibility of a novel direct electrostatic arc ignition method for hybrid motors. A series of small prototype stand-alone thrusters demonstrating this technology were successfully designed and tested using Acrylonitrile Butadiene Styrene (ABS) plastic and Gaseous Oxygen (GOX) as propellants. Measurements of input voltage and current demonstrated that arc-ignition will occur using as little as 10 watts peak power and less than 5 joules total energy. The motor developed for the stand-alone small thruster was adapted as a gas generator to ignite a medium-scale hybrid rocket motor using nitrous oxide /and HTPB as propellants. Multiple consecutive ignitions were performed. A large data set as well as a collection of development `lessons learned' were compiled to guide future development and research. Since the completion of this original groundwork research, the concept has been developed into a reliable, operational igniter system for a 75mm hybrid motor using both gaseous oxygen and liquid nitrous oxide as oxidizers. A development map of the direct spark ignition concept is presented showing the flow of key lessons learned between this original work and later follow on development.

Coil-On-Plug Ignition for Oxygen/Methane Liquid Rocket Engines in Thermal-Vacuum Environments

NASA Technical Reports Server (NTRS)

Melcher, John C.; Atwell, Matthew J.; Morehead, Robert L.; Hurlbert, Eric A.; Bugarin, Luz; Chaidez, Mariana

2017-01-01

A coil-on-plug ignition system has been developed and tested for Liquid Oxygen (LOX)/liquid methane (LCH4) rocket engines operating in thermal vacuum conditions. The igniters were developed and tested as part of the Integrated Cryogenic Propulsion Test Article (ICPTA), previously tested as part of the Project Morpheus test vehicle. The ICPTA uses an integrated, pressure-fed, cryogenic LOX/LCH4 propulsion system including a reaction control system (RCS) and a main engine. The ICPTA was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. A coil-on-plug ignition system has been developed to successfully demonstrate ignition reliability at these conditions while preventing corona discharge issues. The ICPTA uses spark plug ignition for both the main engine igniter and the RCS. The coil-on-plug configuration eliminates the conventional high-voltage spark plug cable by combining the coil and the spark plug into a single component. Prior to ICPTA testing at Plum Brook, component-level reaction control engine (RCE) and main engine igniter testing was conducted at NASA Johnson Space Center (JSC), which demonstrated successful hot-fire ignition using the coil-on-plug from sea-level ambient conditions down to 10(exp -2) torr. Integrated vehicle hot-fire testing at JSC demonstrated electrical and command/data system performance. Lastly, hot-fire testing at Plum Brook demonstrated successful ignitions at simulated altitude conditions at 30 torr and cold thermal-vacuum conditions at 6 torr. The test campaign successfully proved that coil-on-plug technology will enable integrated LOX/LCH4 propulsion systems in future spacecraft.

Coil-On-Plug Ignition for LOX/Methane Liquid Rocket Engines in Thermal Vacuum Environments

NASA Technical Reports Server (NTRS)

Melcher, John C.; Atwell, Matthew J.; Morehead, Robert L.; Hurlbert, Eric A.; Bugarin, Luz; Chaidez, Mariana

2017-01-01

A coil-on-plug ignition system has been developed and tested for Liquid Oxygen (LOX) / liquid methane rocket engines operating in thermal vacuum conditions. The igniters were developed and tested as part of the Integrated Cryogenic Propulsion Test Article (ICPTA), previously tested as part of the Project Morpheus test vehicle. The ICPTA uses an integrated, pressure-fed, cryogenic LOX/methane propulsion system including a reaction control system (RCS) and a main engine. The ICPTA was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. In order to successfully demonstrate ignition reliability in the vacuum conditions and eliminate corona discharge issues, a coil-on-plug ignition system has been developed. The ICPTA uses spark-plug ignition for both the main engine igniter and the RCS. The coil-on-plug configuration eliminates the conventional high-voltage spark plug cable by combining the coil and the spark-plug into a single component. Prior to ICPTA testing at Plum Brook, component-level reaction control engine (RCE) and main engine igniter testing was conducted at NASA Johnson Space Center (JSC), which demonstrated successful hot-fire ignition using the coil-on-plug from sea-level ambient conditions down to 10(exp.-2) torr. Integrated vehicle hot-fire testing at JSC demonstrated electrical and command/data system performance. Lastly, Plum Brook testing demonstrated successful ignitions at simulated altitude conditions at 30 torr and cold thermal-vacuum conditions at 6 torr. The test campaign successfully proved that coil-on-plug technology will enable integrated LOX/methane propulsion systems in future spacecraft.

Piloted Ignition Delay of PMMA in Space Exploration Atmospheres

NASA Technical Reports Server (NTRS)

McAllister, Sara; Fernandez-Pello, Carlos; Urban, David; Ruff, Gary

2007-01-01

In order to reduce the risk of decompression sickness associated with extravehicular activity (EVA), NASA is designing the next generation of exploration vehicles and habitats with a different cabin environment than used previously. The proposed environment uses a total cabin pressure of 52.7 to 58.6 kPa with an oxygen concentration of 30 to 34% by volume and was chosen with material flammability in mind. Because materials may burn differently under these conditions and there is little information on how this new environment affects the flammability of the materials onboard, it is important to conduct material flammability experiments at the intended exploration atmosphere. One method to evaluate material flammability is by its ease of ignition. To this end, piloted ignition delay tests were conducted in the Forced Ignition and Spread Test (FIST) apparatus subject to this new environment. In these tests, polymethylmethacylate (PMMA) was exposed to a range of oxidizer flow velocities and externally applied heat fluxes. Tests were conducted for a baseline case of normal pressure and oxygen concentration, low pressure (58.6 kPa) with normal oxygen (21%), and low pressure with 32% oxygen concentration conditions to determine the individual effect of pressure and the combined effect of pressure and oxygen concentration on the ignition delay. It was found that reducing the pressure while keeping the oxygen concentration at 21% reduced the ignition time by 17% on average. Increasing the oxygen concentration at low pressures reduced the ignition time by an additional 10%. It was also noted that the critical heat flux for ignition decreases at exploration atmospheres. These results show that tests conducted in standard atmospheric conditions will underpredict the ignition of materials intended for use on spacecraft and that, at these conditions, materials are more susceptible to ignition than at current spacecraft atmospheres.

Facile Thermal and Optical Ignition of Silicon Nanoparticles and Micron Particles.

PubMed

Huang, Sidi; Parimi, Venkata Sharat; Deng, Sili; Lingamneni, Srilakshmi; Zheng, Xiaolin

2017-10-11

Silicon (Si) particles are widely utilized as high-capacity electrodes for Li-ion batteries, elements for thermoelectric devices, agents for bioimaging and therapy, and many other applications. However, Si particles can ignite and burn in air at elevated temperatures or under intense illumination. This poses potential safety hazards when handling, storing, and utilizing these particles for those applications. In order to avoid the problem of accidental ignition, it is critical to quantify the ignition properties of Si particles such as their sizes and porosities. To do so, we first used differential scanning calorimetry to experimentally determine the reaction onset temperature of Si particles under slow heating rates (∼0.33 K/s). We found that the reaction onset temperature of Si particles increased with the particle diameter from 805 °C at 20-30 nm to 935 °C at 1-5 μm. Then, we used a xenon (Xe) flash lamp to ignite Si particles under fast heating rates (∼10 3 to 10 6 K/s) and measured the minimum ignition radiant fluence (i.e., the radiant energy per unit surface area of Si particle beds required for ignition). We found that the measured minimum ignition radiant fluence decreased with decreasing Si particle size and was most sensitive to the porosity of the Si particle bed. These trends for the Xe flash ignition experiments were also confirmed by our one-dimensional unsteady simulation to model the heat transfer process. The quantitative information on Si particle ignition included in this Letter will guide the safe handling, storage, and utilization of Si particles for diverse applications and prevent unwanted fire hazards.

40 CFR 1065.230 - Raw exhaust flow meter.

Code of Federal Regulations, 2012 CFR

2012-07-01

... sample NMHC downstream of the cooling for compression-ignition engines, 2-stroke spark-ignition engines, and 4-stroke spark-ignition engines below 19 kW. (3) If cooling causes aqueous condensation, do not...

40 CFR 1065.230 - Raw exhaust flow meter.

Code of Federal Regulations, 2013 CFR

2013-07-01

... sample NMHC downstream of the cooling for compression-ignition engines, 2-stroke spark-ignition engines, and 4-stroke spark-ignition engines below 19 kW. (3) If cooling causes aqueous condensation, do not...

33 CFR 127.1605 - Other sources of ignition.

Code of Federal Regulations, 2011 CFR

2011-07-01

... sources of ignition. Each operator of a waterfront facility handling LHG shall ensure that in the marine... is located where sparks may ignite combustible material; and (d) All rubbish, debris, and waste go...

LLE 2008 annual report, October 2007 - September 2008

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2009-01-31

The research program at the University of Rochester’s Laboratory for Laser Energetics (LLE) focuses on inertial confinement fusion (ICF) research supporting the goal of achieving ignition on the National Ignition Facility (NIF). This program includes the full use of the OMEGA EP Laser System. Within the National Ignition Campaign (NIC), LLE is the lead laboratory for the validation of the performance of cryogenic target implosions, essential to all forms of ICF ignition. LLE has taken responsibility for a number of critical elements within the Integrated Experimental Teams (IET’s) supporting the demonstration of indirect-drive ignition on the NIF and is themore » lead laboratory for the validation of the polardrive approach to ignition on the NIF. LLE is also developing, testing, and building a number of diagnostics to be deployed on the NIF for the NIC.« less

Localized Ignition And Subsequent Flame Spread Over Solid Fuels In Microgravity

NASA Technical Reports Server (NTRS)

Kashiwagi, T.; Nakamura, Y.; Prasad, K.; Baum, H.; Olson, S.; Fujita, O.; Nishizawa, K.; Ito, K.

2003-01-01

Localized ignition is initiated by an external radiant source at the middle of a thin solid sheet under external slow flow, simulating fire initiation in a spacecraft with a slow ventilation flow. Ignition behavior, subsequent transition simultaneously to upstream and downstream flame spread, and flame growth behavior are studied theoretically and experimentally. There are two transition stages in this study; one is the first transition from the onset of the ignition to form an initial anchored flame close to the sample surface, near the ignited area. The second transition is the flame growth stage from the anchored flame to a steady fire spread state (i.e. no change in flame size or in heat release rate) or a quasi-steady state, if either exists. Observations of experimental spot ignition characteristics and of the second transition over a thermally thin paper were made to determine the effects of external flow velocity. Both transitions have been studied theoretically to determine the effects of the confinement by a relatively small test chamber, of the ignition configuration (ignition across the sample width vs spot ignition), and of the external flow velocity on the two transitions over a thermally thin paper. This study is currently extending to two new areas; one is to include a thermoplastic sample such poly(methymethacrylate), PMMA, and the other is to determine the effects of sample thickness on the transitions. The recent results of these new studies on the first transition are briefly reported.

Fluid-solid coupled simulation of the ignition transient of solid rocket motor

NASA Astrophysics Data System (ADS)

Li, Qiang; Liu, Peijin; He, Guoqiang

2015-05-01

The first period of the solid rocket motor operation is the ignition transient, which involves complex processes and, according to chronological sequence, can be divided into several stages, namely, igniter jet injection, propellant heating and ignition, flame spreading, chamber pressurization and solid propellant deformation. The ignition transient should be comprehensively analyzed because it significantly influences the overall performance of the solid rocket motor. A numerical approach is presented in this paper for simulating the fluid-solid interaction problems in the ignition transient of the solid rocket motor. In the proposed procedure, the time-dependent numerical solutions of the governing equations of internal compressible fluid flow are loosely coupled with those of the geometrical nonlinearity problems to determine the propellant mechanical response and deformation. The well-known Zeldovich-Novozhilov model was employed to model propellant ignition and combustion. The fluid-solid coupling interface data interpolation scheme and coupling instance for different computational agents were also reported. Finally, numerical validation was performed, and the proposed approach was applied to the ignition transient of one laboratory-scale solid rocket motor. For the application, the internal ballistics were obtained from the ground hot firing test, and comparisons were made. Results show that the integrated framework allows us to perform coupled simulations of the propellant ignition, strong unsteady internal fluid flow, and propellant mechanical response in SRMs with satisfactory stability and efficiency and presents a reliable and accurate solution to complex multi-physics problems.

Understanding the effects of fire management practices on forest health: implications for weeds and vegetation structure

Treesearch

Anne E. Black; Peter Landres

2012-01-01

Current fire policy to restore ecosystem function and resiliency and reduce buildup of hazardous fuels implies a larger future role for fire (both natural and human ignitions) (USDA Forest Service and U.S. Department of the Interior 2000). Yet some fire management (such as building fire line, spike camps, or helispots) potentially causes both short- and longterm...

Predicted fates of ground-nesting bees in soil heated by wildfire: Thermal tolerances of life stages and a survey of nesting depths

Treesearch

James H. Cane; John L. Neff

2011-01-01

Periodic wildfire defines plant community composition and dynamics in many of the world's semi-arid biomes, whose climates and floras also favor wild bee diversity. Invasive flammable grasses, deforestation, historical fire suppression and human ignition are increasing fire frequency and intensifying its severity, as well as introducing fire to previously...

Intercomparison of Fire Size, Fuel Loading, Fuel Consumption, and Smoke Emissions Estimates on the 2006 Tripod Fire, Washington, USA

Treesearch

Stacy A. Drury; Narasimhan Larkin; Tara T. Strand; ShihMing Huang; Scott J. Strenfel; Theresa E. O' Brien; Sean M. Raffuse

2014-01-01

Land managers rely on prescribed burning and naturally ignited wildfires for ecosystem management, and must balance trade-offs of air quality, carbon storage, and ecosystem health. A current challenge for land managers when using fire for ecosystem management is managing smoke production. Smoke emissions are a potential human health hazard due to the production of fine...

Dynamic, Hot Surface Ignition of Aircraft Fuels and Hydraulic Fluids

DTIC Science & Technology

1980-10-01

fuels on a heated stainless steel surface. Higher local surface air speeds necessitated higher surface temperatures for ignition of an applied fluid._-7...Aircraft Fuels ( stainless steel surface) 8. Air Speed and Surface Material Effects on Hot Surface 21 Ignition Temperature of Aircraft Fuels (Titanium...Material Effects on Hot Surface 26 Ignition Temperature of Aircraft Hydraulic Fluids ( Stainless steel surface) 11. Air Speed and Surface Material

Critical mass flux for flaming ignition of wood as a function of external radiant heat flux and moisture content

Treesearch

S. McAllister; M. Finney; J. Cohen

2011-01-01

Extreme weather often contributes to crown fires, where the fire spreads from one tree crown to the next as a series of piloted ignitions. An important aspect in predicting crown fires is understanding the ignition of fuel particles. The ignition criterion considered in this work is the critical mass flux criterion - that a sufficient amount of pyrolysis gases must be...

Propellant Crack Tip Ignition and Propagation under Rapid Pressurization

DTIC Science & Technology

1982-10-01

that the ignition-delay time decreases and the heat flux to the propellant surface increases as the pressurization rate is increased. The decrease in...leading to ignition. The model predicts the experimental obseriation that the ignition delay time decreases as the pressurization rate is increased...pressurization rate on both crack propagation velocity and time variation of crack shape was studied. Experimental results indicated that the crack velocity

Critical mass flux for flaming ignition of dead, dry wood as a function of exernal radiant heat flux

Treesearch

Sara McAllister; Mark Finney; Jack Cohen

2010-01-01

Extreme weather often contributes to crown fires, where the fire spreads from one tree crown to the next as a series of piloted ignitions. An important aspect in predicting crown fires is understanding the ignition of fuel particles. The ignition criterion considered in this work is the critical mass flux criterion - that a sufficient amount of pyrolysis gases must be...

A study of ignition phenomena of bulk metals by radiant heating

NASA Technical Reports Server (NTRS)

Branch, Melvin C.; Abbud-Madrid, A.; Feiereisen, T. J.; Daily, J. W.

1993-01-01

Early research on combustion of metals was motivated by the knowledge of the large heat release and corresponding high temperatures associated with metal-oxygen reactions. The advent of space flight brought about an increased interest in the ignition and combustion of metallic particles as additives in solid rocket propellants. More recently, attention has been given to the flammability properties of bulk, structural metals due to the number of accidental explosions of metal components in high-pressure oxygen systems. The following work represents a preliminary study that is part of a broader research effort aimed at providing further insight into the phenomena of bulk metal combustion by looking at the effects of gravity on the ignition behavior of metals. The scope of this preliminary experimental study includes the use of a non-coherent, continuous radiation ignition source, the measurement of temperature profiles of a variety of metals and a qualitative observation of the ignition phenomena at normal gravity. The specific objectives of the investigation include: (1) a feasibility study of the use of a continuous radiation source for metal ignition; (2) testing and characterization of the ignition behavior of a variety of metals; and (3) building a preliminary experimental database on ignition of metals under normal gravity conditions.

Laser ignition of engines: a realistic option!

NASA Astrophysics Data System (ADS)

Weinrotter, M.; Srivastava, D. K.; Iskra, K.; Graf, J.; Kopecek, H.; Klausner, J.; Herdin, G.; Wintner, E.

2006-01-01

Due to the demands of the market to increase efficiencies and power densities of gas engines, existing ignition schemes are gradually reaching their limits. These limitations initially triggered the development of laser ignition as an effective alternative, first only for gas engines and now for a much wider range of internal combustion engines revealing a number of immediate advantages like no electrode erosion or flame kernel quenching. Furthermore and most noteworthy, already the very first engine tests about 5 years ago had resulted in a drastic reduction of NO x emissions. Within this broad range investigation, laser plasmas were generated by ns Nd-laser pulses and characterized by emission and Schlieren diagnostic methods. High-pressure chamber experiments with lean hydrogen-methane-air mixtures were successfully performed and allowed the determination of essential parameters like minimum pulse energies at different ignition pressures and temperatures as well as at variable fuel air compositions. Multipoint ignition was studied for different ignition point locations. In this way, relevant parameters were acquired allowing to estimate future laser ignition systems. Finally, a prototype diode-pumped passively Q-switched Nd:YAG laser was tested successfully at a gasoline engine allowing to monitor the essential operation characteristics. It is expected that laser ignition involving such novel solid-state lasers will allow much lower maintenance efforts.

Ignition and combustion of lunar propellants

NASA Technical Reports Server (NTRS)

Burton, Rodney L.; Roberts, Ted A.; Krier, Herman

1993-01-01

The ignition and combustion of Al, Mg, and Al/Mg alloy particles in 99 percent O2/1 percent N2 mixtures is investigated at high temperatures and pressures for rocket engine applications. The 20 micron particles contain 0, 5, 10, 20, 40, 60, 80, and 100 weight percent Mg alloyed with Al, and are ignited in oxygen using the reflected shock in a shock tube near the endwall. Using this technique, the ignition delay and combustion times of the particles are measured at temperatures up to 3250 K as a function of Mg content for oxygen pressures of 8.5, 17, and 34 atm. An ignition model is developed which employs a simple lumped capacitance energy equation and temperature and pressure dependent particle and gas properties. Good agreement is achieved between the measured and predicted trends in the ignition delay times. For the particles investigated, the contribution of heterogeneous reaction to the heating of the particle is found to be significant at lower temperatures, but may be neglected as gas temperatures above 3000 K. As little as 10 percent Mg reduces the ignition delay time substantially at all pressures tested. The particle ignition delay times decrease with increasing Mg content, and this reduction becomes less pronounced as oxidizer temperature and pressure are increased.

Theory of hydro-equivalent ignition for inertial fusion and its applications to OMEGA and the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nora, R.; Betti, R.; Bose, A.

The theory of ignition for inertial confinement fusion capsules [R. Betti et al., Phys. Plasmas 17, 058102 (2010)] is used to assess the performance requirements for cryogenic implosion experiments on the Omega Laser Facility. The theory of hydrodynamic similarity is developed in both one and two dimensions and tested using multimode hydrodynamic simulations with the hydrocode DRACO [P. B. Radha et al., Phys. Plasmas 12, 032702 (2005)] of hydro-equivalent implosions (implosions with the same implosion velocity, adiabat, and laser intensity). The theory is used to scale the performance of direct-drive OMEGA implosions to the National Ignition Facility (NIF) energy scalesmore » and determine the requirements for demonstrating hydro-equivalent ignition on OMEGA. Hydro-equivalent ignition on OMEGA is represented by a cryogenic implosion that would scale to ignition on the NIF at 1.8 MJ of laser energy symmetrically illuminating the target. It is found that a reasonable combination of neutron yield and areal density for OMEGA hydro-equivalent ignition is 3 to 6 × 10{sup 13} and ∼0.3 g/cm{sup 2}, respectively, depending on the level of laser imprinting. This performance has not yet been achieved on OMEGA.« less

X-ray driven implosions at ignition relevant velocities on the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meezan, N. B.; MacKinnon, A. J.; Hicks, D. G.

2013-05-15

Backlit convergent ablator experiments on the National Ignition Facility [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] are indirect drive implosions that study the inflight dynamics of an imploding capsule. Side-on, backlit radiography provides data used by the National Ignition Campaign to measure time-dependent properties of the capsule ablator including its center of mass radius, velocity, and unablated mass. Previously, Callahan [D. A. Callahan et al., Phys. Plasmas 19, 056305 (2012)] and Hicks [D. H. Hicks et al., Phys. Plasmas 19, 122702 (2012)] reported backlit convergent ablator experiments demonstrating velocities approaching those required for ignition. This paper focusesmore » on implosion performance data in the “rocket curve” plane, velocity vs. ablator mass. These rocket curve data, along with supporting numerical simulations, show that the nominal 195 μm-thick ignition capsule would reach the ignition velocity goal V = 370 km/s with low ablator mass remaining–below the goal of M = 0.25 mg. This finding led to experiments with thicker capsule ablators. A recent symmetry capsule experiment with a 20 μm thicker capsule driven by 520 TW, 1.86 MJ laser pulse (along with a companion backlit convergent ablator experiment) appears to have demonstrated V≥350 km/s with ablator mass remaining above the ignition goal.« less

Influence of gas temperature on ignition, burning and extinction of carbon particles-gas suspension

NASA Astrophysics Data System (ADS)

Orlovskaya, S. G.; Zuy, O. N.; Liseanskaia, M. V.

2017-11-01

The ignition and burning of monodisperse and two-fraction suspensions of carbon particles at gas temperature in the range 1100 ÷ 1500 K are modeled. The critical gas temperature of the suspension ignition, the particles ignition delay and burning time, the burning temperature, and the extinction parameters are determined. The data obtained are compared with burning characteristics of single particle of equal size. The ignition temperatures of the fine fraction (the particle diameter 60 μm) and the coarse one (120 μm) are practically the same. The ignition temperatures of the equivalent single particles are much higher and they differ by 100 K and more. The gas temperature is found below which the ignition delay of the fine fraction exceeds the one of the coarse fraction. It is found that, at critical ignition temperatures the burning temperature of the fine fraction is lower than that of the coarse fraction. At gas temperatures above 1250 K, the burning temperature of the fine fraction is higher. It is established that, in contrast to single particles, the temperature difference between the particles and the gas is small during gas-suspension extinction. Further oxidation of the particles occurs in the kinetic regime, so it is possible to estimate the time of their complete conversion.

Towards the dynamic prediction of wildfire danger. Modeling temporal scenarios of fire-occurrence in Northeast Spain

NASA Astrophysics Data System (ADS)

Martín, Yago; Rodrigues, Marcos

2017-04-01

Up to date models of human-caused ignition probability have commonly been developed from a static or structural point of view, regardless of the time cycles that drive human behavior or environmental conditions. However, human drivers mostly have a temporal dimension, and fuel conditions are subjected to temporal changes as well, which is why a historical/temporal perspective is often required. Previous studies in the region suggest that human driving factors of wildfires have undergone significant shifts in inter-annual occurrence probability models, thus varying over time. On the other hand, an increasing role of environmental conditions has also been reported. This research comprehensively analyzes the intra-annual dimension of fire occurrence and fire-triggering factors using NW Spain as a test area, moving one-step forward towards achieving more accurate predictions, to ultimately develop dynamic predictive models. To this end, several intra-annual presence-only models have been calibrated, exploring seasonal variations of environmental conditions and short-term cycles of human activity (working- vs non-working days). Models were developed from accurately geolocated fire data in the 2008-2012 period, and GIS and remote sensing (MOD1A2 and MOD16) information . Specifically, 8 occurrence data subsets (scenarios) were constructed by splitting fire records into 4 seasons (winter, spring, summer and autumn) then separating each season into 2 new categories (working and non-working days). This allows analyzing the temporal variation of socioeconomic (urban- and agricultural-interfaces, transport and road networks, and human settlements) and environmental (fuel conditions) factors associated with occurrence. Models were calibrated applying the Maximum Entropy algorithm (MaxEnt). The MaxEnt algorithm was selected as it is the most widespread approach to deal with presence-only data, as may be the case of fire occurrence. The dependent variable for each scenario was created on a conceptual framework which assumed that there were no true cases of fire absence. Model accuracy was assessed using a cross-validation k-fold procedure, whereas variable importance was addressed using a jacknife approach combined with AUC estimation. Results reported model performances around 0.8 AUC in all temporal scenarios. In addition, large variability was observed in the contribution of explanatory factors, with accessibility variables and fuel conditions as key factors along models. Overall, we believe our approach is reliable enough to derive dynamic predictions of human-caused fire occurrence probability. To our knowledge, this is the first attempt to combine presence-only models based on XY located fire data, with remote sensing information and intra-annual scenarios also including cycles of human activity.

Chemistry of Aviation Fuels

NASA Technical Reports Server (NTRS)

Knepper, Bryan; Hwang, Soon Muk; DeWitt, Kenneth J.

2004-01-01

Minimum ignition energies of various methanol/air mixtures were measured in a temperature controlled constant volume combustion vessel using a spark ignition method with a spark gap distance of 2 mm. The minimum ignition energies decrease rapidly as the mixture composition (equivalence ratio, Phi) changes from lean to stoichiometric, reach a minimum value, and then increase rather slowly with Phi. The minimum of the minimum ignition energy (MIE) and the corresponding mixture composition were determined to be 0.137 mJ and Phi = 1.16, a slightly rich mixture. The variation of minimum ignition energy with respect to the mixture composition is explained in terms of changes in reaction chemistry.

Ignition of PTFE-lined flexible hoses by rapid pressurization with oxygen

NASA Technical Reports Server (NTRS)

Janoff, Dwight; Bamford, Larry J.; Newton, Barry E.; Bryan, Coleman J.

1989-01-01

A high-volume pneumatic-impact system has been used to test PTFE-lined stainless steel braided hoses, in order to characterize the roles played in the mechanism of oxygen-induced ignition by impact pressure, pressurization rate, and upstream and downstream volumes of the hose. Ignitions are noted to have occurred at impact pressures well below the working pressure of the hoses, as well as at pressurization rates easily obtainable through manual operation of valves. The use of stainless steel hardlines downstream of the hose prevented ignitions at all pressures and pressurization rates; internal observations have shown evidence of shock ionization in the oxygen prior to ignition.

Ignition of PTFE-lined flexible hoses by rapid pressurization with oxygen

NASA Astrophysics Data System (ADS)

Janoff, Dwight; Bamford, Larry J.; Newton, Barry E.; Bryan, Coleman J.

A high-volume pneumatic-impact system has been used to test PTFE-lined stainless steel braided hoses, in order to characterize the roles played in the mechanism of oxygen-induced ignition by impact pressure, pressurization rate, and upstream and downstream volumes of the hose. Ignitions are noted to have occurred at impact pressures well below the working pressure of the hoses, as well as at pressurization rates easily obtainable through manual operation of valves. The use of stainless steel hardlines downstream of the hose prevented ignitions at all pressures and pressurization rates; internal observations have shown evidence of shock ionization in the oxygen prior to ignition.

Improved Performance of High Areal Density Indirect Drive Implosions at the National Ignition Facility using a Four-Shock Adiabat Shaped Drive

DOE PAGES

Casey, D. T.; Milovich, J. L.; Smalyuk, V. A.; ...

2015-09-01

Hydrodynamic instabilities can cause capsule defects and other perturbations to grow and degrade implosion performance in ignition experiments at the National Ignition Facility (NIF). Here, we show the first experimental demonstration that a strong unsupported first shock in indirect drive implosions at the NIF reduces ablation front instability growth leading to a 3 to 10 times higher yield with fuel ρR > 1 g=cm 2. This work shows the importance of ablation front instability growth during the National Ignition Campaign and may provide a path to improved performance at the high compression necessary for ignition.

40 CFR 1065.230 - Raw exhaust flow meter.

Code of Federal Regulations, 2014 CFR

2014-07-01

... sample NMHC downstream of the cooling for compression-ignition engines, two-stroke spark-ignition engines, or four-stroke spark-ignition engines at or below 19 kW. (3) The cooling must not cause aqueous...

The effect of ignition location on explosion venting of hydrogen-air mixtures

NASA Astrophysics Data System (ADS)

Cao, Y.; Guo, J.; Hu, K.; Xie, L.; Li, B.

2017-07-01

The effect of ignition location and vent burst pressure on the internal pressure-time history and external flame propagation was investigated for vented explosions of hydrogen-air mixtures in a small cylindrical vessel. A high-speed camera was used to record videos of the external flame while pressure transducers were used to record pressure-time histories. It was found that central ignition always leads to the maximum internal peak overpressure, and front ignition resulted in the lowest value of internal peak overpressure. The internal peak overpressures are increased corresponding to the increase in the vent burst pressure in the cases of central and rear ignition. Because of the effect of acoustic oscillations, the phenomenon of oscillations is observed in the internal pressure profile for the case of front ignition. The pressure oscillations for the cases of rear and central ignition are triggered by external explosions. The behavior of flames outside the chamber is significantly associated with the internal pressure of the chamber so that the velocity of the jet flame is closely related to the internal overpressure peak.

Laser-induced breakdown ignition in a gas fed two-stroke engine

NASA Astrophysics Data System (ADS)

Loktionov, E. Y.; Pasechnikov, N. A.; Telekh, V. D.

2018-01-01

Laser-induced ignition for internal combustion engines is investigated intensively after demonstration of a compact ‘laser plug’ possibility. Laser spark benefits as compared to traditional spark plugs are higher compression rate, and possibility of almost any fuel ignition, so lean mixtures burning with lower temperatures could reduce harmful exhausts (NO x , CH, etc). No need in electrode and possibility for multi-point, linear or circular ignition can make combustion even more effective. Laser induced combustion wave appears faster and is more stable in time, than electric one, so can be used for ramjets, chemical thrusters, and gas turbines. To the best of our knowledge, we have performed laser spark ignition of a gas fed two-stroke engine for the first time. Combustion temperature and pressure, exhaust composition, ignition timing were investigated at laser and compared to a regular electric spark ignition in a two-stroke model engine. Presented results show possibility for improvement of two-stroke engines performance, in terms of rotation rate increase and NO x emission reduction. Such compact engines using locally mined fuel could be highly demanded in remote Arctic areas.

Laser-assisted homogeneous charge ignition in a constant volume combustion chamber

NASA Astrophysics Data System (ADS)

Srivastava, Dhananjay Kumar; Weinrotter, Martin; Kofler, Henrich; Agarwal, Avinash Kumar; Wintner, Ernst

2009-06-01

Homogeneous charge compression ignition (HCCI) is a very promising future combustion concept for internal combustion engines. There are several technical difficulties associated with this concept, and precisely controlling the start of auto-ignition is the most prominent of them. In this paper, a novel concept to control the start of auto-ignition is presented. The concept is based on the fact that most HCCI engines are operated with high exhaust gas recirculation (EGR) rates in order to slow-down the fast combustion processes. Recirculated exhaust gas contains combustion products including moisture, which has a relative peak of the absorption coefficient around 3 μm. These water molecules absorb the incident erbium laser radiations ( λ=2.79 μm) and get heated up to expedite ignition. In the present experimental work, auto-ignition conditions are locally attained in an experimental constant volume combustion chamber under simulated EGR conditions. Taking advantage of this feature, the time when the mixture is thought to "auto-ignite" could be adjusted/controlled by the laser pulse width optimisation, followed by its resonant absorption by water molecules present in recirculated exhaust gas.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tarver, C M

Recent laser ignition experiments on octahydro-1,3,5,7-tetranitro-1,3,5,7-terrazocine (HMX) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) subjected to laser fluxes ranging from 10 to 800 W/cm{sup 2} produced ignition times from seconds to milliseconds. Global chemical kinetic thermal decomposition models for HMX and TATB have been developed to calculate times to thermal explosion for experiments in the seconds to days time frame. These models are applied to the laser ignition experimental data in this paper. Excellent agreement was obtained for TATB, while the calculated ignition times were longer than experiment for HMX at lower laser fluxes. At the temperatures produced in the laser experiments, HMX melts.more » Melting generally increases condensed phase reaction rates so faster rates were used for three of the HMX reaction rates. This improved agreement with experiments at the lower laser fluxes but yielded very fast ignition at high fluxes. The calculated times to ignition are in reasonable agreement with the laser ignition experiments, and this justifies the use of these models for estimating reaction times at impact and shock ''hot spot'' temperatures.« less

Conservation threats due to human-caused increases in fire frequency in Mediterranean-climate ecosystems.

PubMed

Syphard, Alexandra D; Radeloff, Volker C; Hawbaker, Todd J; Stewart, Susan I

2009-06-01

Periodic wildfire is an important natural process in Mediterranean-climate ecosystems, but increasing fire recurrence threatens the fragile ecology of these regions. Because most fires are human-caused, we investigated how human population patterns affect fire frequency. Prior research in California suggests the relationship between population density and fire frequency is not linear. There are few human ignitions in areas with low population density, so fire frequency is low. As population density increases, human ignitions and fire frequency also increase, but beyond a density threshold, the relationship becomes negative as fuels become sparser and fire suppression resources are concentrated. We tested whether this hypothesis also applies to the other Mediterranean-climate ecosystems of the world. We used global satellite databases of population, fire activity, and land cover to evaluate the spatial relationship between humans and fire in the world's five Mediterranean-climate ecosystems. Both the mean and median population densities were consistently and substantially higher in areas with than without fire, but fire again peaked at intermediate population densities, which suggests that the spatial relationship is complex and nonlinear. Some land-cover types burned more frequently than expected, but no systematic differences were observed across the five regions. The consistent association between higher population densities and fire suggests that regardless of differences between land-cover types, natural fire regimes, or overall population, the presence of people in Mediterranean-climate regions strongly affects the frequency of fires; thus, population growth in areas now sparsely settled presents a conservation concern. Considering the sensitivity of plant species to repeated burning and the global conservation significance of Mediterranean-climate ecosystems, conservation planning needs to consider the human influence on fire frequency. Fine-scale spatial analysis of relationships between people and fire may help identify areas where increases in fire frequency will threaten ecologically valuable areas. ©2009 Society for Conservation Biology.

Pulse ignition characterization of mercury ion thruster hollow cathode using an improved pulse ignitor

NASA Technical Reports Server (NTRS)

Wintucky, E. G.; Gruber, R. P.

1978-01-01

An investigation of the high voltage pulse ignition characteristics of the 8 cm mercury ion thruster neutralizer cathode identified a low rate of voltage rise and long pulse duration as desirable factors for reliable cathode starting. Cathode starting breakdown voltages were measured over a range of mercury flow rates and tip heater powers for pulses with five different rates of voltage rise. Breakdown voltage requirements for the fastest rising pulse (2.5 to 3.0 kV/micro sec) were substantially higher (2 kV or more) than for the slowest rising pulse (0.3 to 0.5 kV/micro sec) for the same starting conditions. Also described is an improved, low impedance pulse ignitor circuit which reduces power losses and eliminates problems with control and packaging associated with earlier designs.

The status of Fast Ignition Realization Experiment (FIREX) and prospects for inertial fusion energy

NASA Astrophysics Data System (ADS)

Azechi, H.; FIREX Project Team

2016-05-01

Here we report recent progress for the fast ignition inertial confinement fusion demonstration. The fraction of low energy (< 1 MeV) component of the relativistic electron beam (REB), which efficiently heats the fuel core, increases by a factor of 4 by enhancing pulse contrast of heating laser and removing preformed plasma sources. Kilo-tesla magnetic field is studied to guide the diverging REB to the fuel core. The transport simulation of the REB accelerated by the heating laser in the externally applied and compressed magnetic field indicates that the REB can be guided efficiently to the fuel core. The integrated simulation shows > 4% of the heating efficiency and > 4 keV of ion temperature are achievable by using GEKKO-XII and LFEX, properly designed cone-fuel and an external magnetic field.

Debris and shrapnel assessments for National Ignition Facility targets and diagnostics

NASA Astrophysics Data System (ADS)

Masters, N. D.; Fisher, A.; Kalantar, D.; Stölken, J.; Smith, C.; Vignes, R.; Burns, S.; Doeppner, T.; Kritcher, A.; Park, H.-S.

2016-05-01

High-energy laser experiments at the National Ignition Facility (NIF) can create debris and shrapnel capable of damaging laser optics and diagnostic instruments. The size, composition and location of target components and sacrificial shielding (e.g., disposable debris shields, or diagnostic filters) and the protection they provide is constrained by many factors, including: chamber and diagnostic geometries, experimental goals and material considerations. An assessment of the generation, nature and velocity of shrapnel and debris and their potential threats is necessary prior to fielding targets or diagnostics. These assessments may influence target and shielding design, filter configurations and diagnostic selection. This paper will outline the approach used to manage the debris and shrapnel risk associated with NIF targets and diagnostics and present some aspects of two such cases: the Material Strength Rayleigh- Taylor campaign and the Mono Angle Crystal Spectrometer (MACS).

National Ignition Facility project acquisition plan revision 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clobes, A.R.

The purpose of this National Ignition Facility Acquisition Plan is to describe the overall procurement strategy planned for the National Ignition Facility M Project. It was prepared for the NIP Prood Office by the NIF Procurement Manager.

Potential of Spark Ignition Engine, 1979 Summary Source Document

DOT National Transportation Integrated Search

1980-03-01

This report provides an assessment of the potential for spark ignition engines passenger cars and light trucks. The assessment includes: tradeoffs between fuel economy and emissions; improvements in spark ignition engine efficiency; improvements in e...