This paper applies a pragmatic interval-based approach to validation of a fire dynamics model involving computational fluid dynamics, combustion, participating-media radiation, and heat transfer. Significant aleatory and epistemic sources of uncertainty exist in the experiments and simulations. The validation comparison of experimental and simulation results, and corresponding criteria and procedures for model affirmation or refutation, take place in "real space" as opposed to "difference space" where subtractive differences between experiments and simulations are assessed. The versatile model validation framework handles difficulties associated with representing and aggregating aleatory and epistemic uncertainties from multiple correlated and uncorrelated source types, including: • experimental variability from multiple repeat experiments • uncertainty of experimental inputs • experimental output measurement uncertainties • uncertainties that arise in data processing and inference from raw simulation and experiment outputs • parameter and model-form uncertainties intrinsic to the model • numerical solution uncertainty from model discretization effects. The framework and procedures of the model validation methodology are here applied to a difficult validation problem involving experimental and predicted calorimeter temperatures in a wind-driven hydrocarbon pool fire.
The objective of this work is to perform an uncertainty quantification (UQ) and model validation analysis of simulations of tests in the cross-wind test facility (XTF) at Sandia National Laboratories. In these tests, a calorimeter was subjected to a fire and the thermal response was measured via thermocouples. The UQ and validation analysis pertains to the experimental and predicted thermal response of the calorimeter. The calculations were performed using Sierra/Fuego/Syrinx/Calore, an Advanced Simulation and Computing (ASC) code capable of predicting object thermal response to a fire environment. Based on the validation results at eight diversely representative TC locations on the calorimeter the predicted calorimeter temperatures effectively bound the experimental temperatures. This post-validates Sandia's first integrated use of fire modeling with thermal response modeling and associated uncertainty estimates in an abnormal-thermal QMU analysis.
A joint temperature/soot laser-based optical diagnostic was developed for the determination of the joint temperature/soot probability density function (PDF) for hydrocarbon-fueled meter-scale turbulent pool fires. This Laboratory Directed Research and Development (LDRD) effort was in support of the Advanced Simulation and Computing (ASC) program which seeks to produce computational models for the simulation of fire environments for risk assessment and analysis. The development of this laser-based optical diagnostic is motivated by the need for highly-resolved spatio-temporal information for which traditional diagnostic probes, such as thermocouples, are ill-suited. The in-flame gas temperature is determined from the shape of the nitrogen Coherent Anti-Stokes Raman Scattering (CARS) signature and the soot volume fraction is extracted from the intensity of the Laser-Induced Incandescence (LII) image of the CARS probed region. The current state of the diagnostic will be discussed including the uncertainty and physical limits of the measurements as well as the future applications of this probe.
In 2004, at the request of the Department of Energy, Sandia National Laboratories (Sandia) prepared a report, ''Guidance on the Risk and Safety Analysis of Large Liquefied Natural Gas (LNG) Spills Over Water''. That report provided framework for assessing hazards and identifying approaches to minimize the consequences to people and property from an LNG spill over water. The report also presented the general scale of possible hazards from a spill from 125,000 m3 o 150,000 m3 class LNG carriers, at the time the most common LNG carrier capacity.
In March 2005, the United States Coast Guard requested that Sandia National Laboratories provide a technical review and evaluation of the appropriateness and completeness of models, assumptions, analyses, and risk management options presented in the Cabrillo Port LNG Deepwater Port Independent Risk Assessment-Revision 1 (Cabrillo Port IRA). The goal of Sandia's technical evaluation of the Cabrillo Port IRA was to assist the Coast Guard in ensuring that the hazards to the public and property from a potential LNG spill during transfer, storage, and regasification operations were appropriately evaluated and estimated. Sandia was asked to review and evaluate the Cabrillo Port IRA results relative to the risk and safety analysis framework developed in the recent Sandia report, ''Guidance on Risk Analysis and Safety Implications of a Large Liquefied Natural Gas (LNG) Spill over Water''. That report provides a framework for assessing hazards and identifying approaches to minimize the consequences to people and property from an LNG spill over water. This report summarizes the results of the Sandia review of the Cabrillo Port IRA and supporting analyses. Based on our initial review, additional threat and hazard analyses, consequence modeling, and process safety considerations were suggested. The additional analyses recommended were conducted by the Cabrillo Port IRA authors in cooperation with Sandia and a technical review panel composed of representatives from the Coast Guard and the California State Lands Commission. The results from the additional analyses improved the understanding and confidence in the potential hazards and consequences to people and property from the proposed Cabrillo Port LNG Deepwater Port Project. The results of the Sandia review, the additional analyses and evaluations conducted, and the resolutions of suggested changes for inclusion in a final Cabrillo Port IRA are summarized in this report.
While recognized standards exist for the systematic safety analysis of potential spills or releases from LNG (Liquefied Natural Gas) storage terminals and facilities on land, no equivalent set of standards or guidance exists for the evaluation of the safety or consequences from LNG spills over water. Heightened security awareness and energy surety issues have increased industry's and the public's attention to these activities. The report reviews several existing studies of LNG spills with respect to their assumptions, inputs, models, and experimental data. Based on this review and further analysis, the report provides guidance on the appropriateness of models, assumptions, and risk management to address public safety and property relative to a potential LNG spill over water.