A Study of the Blast Wave Shape from Elongated VCEs

PresentationElongated congestion patterns are common at chemical processing and petroleum refining facilities due to the arrangement of processing units. The accidental vapor cloud explosion (VCE) which occurred at the Buncefield, UK facility involved an elongated congested volume formed by the trees and undergrowth along the site boundary. Although elongated congested volumes are common, there have been few evaluations reported for the blast loads produced by elongated VCEs. Standard VCE blast load prediction techniques do not directly consider the impact of this congested volume geometry versus a more compact geometry. This paper discusses an evaluation performed to characterize the blast loads from elongated VCEs and identified some significant differences in the resulting blast wave shape versus those predicted by well-known VCE blast load methodologies (e.g., BST and TNO MEM). The standard blast curves are based on an assumption that the portion of the flammable gas cloud participating in the VCE is hemispherical and located at grade level. The results of this evaluation showed that the blast wave shape for a deflagration in an elongated congested volume is similar to that for an acoustic wave in the near-field along the long-axis direction. Like an acoustic wave, an elongated VCE blast wave has a very quick transition from the positive phase peak pressure to the negative phase peak pressure, relative to the positive phase duration. The magnitude of the applied negative pressure on a building face depends strongly on the transition time between the positive and negative phase peak pressures, and this applied negative phase can be important to structural response under certain conditions. The main purpose of this evaluation was to extend previous work in order to investigate how an elongated VCE geometry impacts the resultant blast wave shape in the near-field. The influence of the normalized flame travel distance and the flame speed on the blast wave shape is also examined

Synthetic Digital Ecologies: Proceedings of the 32nd Annual Conference of the Association for Computer Aided Design in Architecture

Why use the terms synthetic and ecology in the context of a conference dedicated to the field of digital architecture, computation and fabrication? How do we begin to unpack the synthetic union of diverse elements, processes, collaborators, and code underlying any single contemporary design or research project? What could our field gain by interrogating these diverse ecologies? What are the relationships and interactions between our design processes, including our various tools and techniques, and the multiple environments with which we routinely work, collaborate and make? It is these questions and more that we hope to address at this year’s “Synthetic Digital Ecologies” conference. A quick scan of the papers and projects that will be presented at ACADIA reveals an extraordinary ecology of experimental research that emerged by working between messy labs, studios, workshops, hacker spaces and the like. In many ways today’s so-called “digital architects” do not feel compelled to distinguish between what is digitally designed and what is not. They are leading the way through a promiscuous and synthetic mixing of skill sets, of pens and paper, hardware and software, electronics and g-code. In a single research project these designers might collaborate with a computer scientist, a robotics expert and a glass blower, and in many cases they might even attempt to do all of these things themselves. It was with this in mind that we put forth an international call inviting, “… architects, fabricators, engineers, media artists, technologists, software developers, hackers and others in related fields of inquiry …” to submit papers and projects for this year’s conference. This year the proceedings have been organized into twelve synthetic categories based around the potential for diverse research topics to inform new and unexpected conversations. Instead of organizing peer-reviewed papers and projects through their formal characteristics, we were interested in forming new synthetic categories by curating unexpected juxtapositions. This ecology of ideas and research was meant to provoke and inspire new ways of thinking, making, building and collaborating

Experiments with neutron induced neutron emission from U-235, Pu-239, and graphite

A neutron induced neutron emission experiment was conducted as the Los Alamos Neutron Science Center (LANSCE) facility at Los Alamos National Laboratory (LANL). In this experiment, a sample was placed in a well collimated neutron beam and was surrounded by an array of 28 fast neutron detectors (EJ-309). The experiment was performed with a neutron flight path of 21.5 m from the source to the sample, and 1 m from the sample to the detectors. The neutron emission from the sample was measured as a function of neutron time of flight covering an incident energy range from 0.7- 20 MeV. The samples included U-235, Pu-239, carbon (graphite), and blanks that matched the encapsulation of the sample. The measured samples were constantly cycled in and out of the neutron beam. This type of experiment measures neutron emission from all reactions occurring in the sample such as fission and elastic and inelastic scattering. Similar to the methodology previously developed at RPI [1], the measurements were compared with detailed simulations of the experiment using different cross section evaluations for the sample. The observed differences can be attributed to the evaluated neutron cross section and angular distributions. The carbon sample was used as a reference to validate both the experiment and simulation methodology and showed good agreement between experiments and simulations. A review of the experimental setup, analysis methods, and some of the results will be presented

Experiments with neutron induced neutron emission from U-235, Pu-239, and graphite

A neutron induced neutron emission experiment was conducted as the Los Alamos Neutron Science Center (LANSCE) facility at Los Alamos National Laboratory (LANL). In this experiment, a sample was placed in a well collimated neutron beam and was surrounded by an array of 28 fast neutron detectors (EJ-309). The experiment was performed with a neutron flight path of 21.5 m from the source to the sample, and 1 m from the sample to the detectors. The neutron emission from the sample was measured as a function of neutron time of flight covering an incident energy range from 0.7- 20 MeV. The samples included U-235, Pu-239, carbon (graphite), and blanks that matched the encapsulation of the sample. The measured samples were constantly cycled in and out of the neutron beam. This type of experiment measures neutron emission from all reactions occurring in the sample such as fission and elastic and inelastic scattering. Similar to the methodology previously developed at RPI [1], the measurements were compared with detailed simulations of the experiment using different cross section evaluations for the sample. The observed differences can be attributed to the evaluated neutron cross section and angular distributions. The carbon sample was used as a reference to validate both the experiment and simulation methodology and showed good agreement between experiments and simulations. A review of the experimental setup, analysis methods, and some of the results will be presented