Publications

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Solid rocket propellant plume temperatures have been measured using spectroscopic methods as part of an ongoing effort to specify the thermal-chemical-physical environment in and around a burning fragment of an exploded solid rocket at atmospheric pressures. Such specification is needed for launch safety studies where hazardous payloads become involved with large fragments of burning propellant. The propellant burns in an off-design condition producing a hot gas flame loaded with burning metal droplets. Each component of the flame (soot, droplets and gas) has a characteristic temperature, and it is only through the use of spectroscopy that their temperature can be independently identified.

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Accidents involving solid propellants containing aluminum can be difficult to model due to the additional heat transfer from molten aluminum or aluminum combustion and impingement/deposition of oxide on target objects. A series of tests has been carried out using a commercially available oxy-acetylene torch and powder feeder to investigate the effects of molten/oxidized aluminum on stainless steel 304 substrates. SEM and EDS have been used to determine diffusion/interaction of aluminum with the stainless steel and characterize the constituents of the resulting interfacial layers. These techniques indicated that at the test conditions, aluminum was undetectably oxidized before it deposited on the substrate surface. However, temperature data from thermocouples attached to backside of each substrate detected an increased heat flux to the substrate when aluminum is introduced into the flame spray. Results also indicate that the boundary layers of the aluminum and stainless steel were well defined implying that little diffusion or solution of the aluminum with the stainless steel occurred. Copyright © 2012 by ASME.

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This paper discusses testing and modeling efforts to experimentally determine, and numerically model the behavior of aluminum at incipient melt conditions. More particularly, the role of the oxide layer which develops on the surface of aluminum which is heating in an oxidizing environment has been found to influence deformation. Several configurations where tested composed of aluminum rods at different orientations with regard to standard gravity, and video images were taken to record movement. Modeling with comparable materials shows similar behavior and encourages additional work where some numerical comparisons could be researched further. © 2011 INTERNATIONAL ASSOCIATION FOR FIRE SAFETY SCIENCE.

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A multifunctional reactor is a chemical engineering device that exploits enhanced heat and mass transfer to promote production of a desired chemical, combining more than one unit operation in a single system. The main component of the reactor system under study here is a vertical column containing packing material through which liquid(s) and gas flow cocurrently downward. Under certain conditions, a range of hydrodynamic regimes can be achieved within the column that can either enhance or inhibit a desired chemical reaction. To study such reactors in a controlled laboratory environment, two experimental facilities were constructed at Sandia National Laboratories. One experiment, referred to as the Two-Phase Experiment, operates with two phases (air and water). The second experiment, referred to as the Three-Phase Experiment, operates with three phases (immiscible organic liquid and aqueous liquid, and nitrogen). This report describes the motivation, design, construction, operational hazards, and operation of the both of these experiments. Data and conclusions are included.

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In the fire safety community, the trend is toward implementing performance-based standards in place of existing prescriptive ones. Prescriptive standards can be difficult to adapt to changing design methods, materials, and application situations of systems that ultimately must perform well in unwanted fire situations. In general, this trend has produced positive results and is embraced by the fire protection community. The question arises as to whether this approach could be used to advantage in cook-off testing. Prescribed fuel fire cook-off tests have been instigated because of historical incidents that led to extensive damage to structures and loss of life. They are designed to evaluate the propensity for a violent response. The prescribed protocol has several advantages: it can be defined in terms of controllable parameters (wind speed, fuel type, pool size, etc.); and it may be conservative for a particular scenario. However, fires are inherently variable and prescribed tests are not necessarily representative of a particular accident scenario. Moreover, prescribed protocols are not necessarily adaptable and may not be conservative. We also consider performance-based testing. This requires more knowledge and thought regarding not only the fire environment, but the behavior of the munitions themselves. Sandia uses a performance based approach in assuring the safe behavior of systems of interest that contain energetic materials. Sandia also conducts prescriptive fire testing for the IAEA, NRC and the DOT. Here we comment on the strengths and weakness of both approaches and suggest a path forward should it be desirable to pursue a performance based cook-off standard.