The risk of terrorist attack on large cryogenic hydrocarbon fuel tankers is unclear, due partly to difficulties in understanding how the spill, pool vaporization, turbulent dispersion and fuel-vapor mixing are coupled. The current study’s objective is to model the vaporization, dispersion, and deflagration of liquid methane pools boiling on water while subjected to airflow around a prismatic body. The Fire Dynamics Simulator CFD code developed by NIST facilitates large-eddy simulations of the turbulent dispersion that is coupled to a combustion model capturing premixed flame ignition, propagation, and if sustainable, transition to diffusion pool fire…
Author: McGill, Jason
Source: University of Maryland
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Contents
CHAPTER 1 – INTRODUCTION
1.1 Shipping of Liquid Hydrocarbons and Potential Hazards
1.1.1 The Growing Significance of LNG to Global Energy Demand
1.1.2 Associated Risk of LNG Transport
1.2 Review of Spill Modeling
1.2.1 Fay Model
1.2.2 Conrado and Vesovic
1.3 Review of Dispersion Modeling for Chemical Spills
1.3.1 Modeling Spill Vaporization
1.3.2 Modeling Turbulent Dispersion
1.4 Fire Dynamic Simulator (FDS)
1.5 Objectives and Approaches
CHAPTER 2 – MODELING TECHNIQUES
2.1 Spill Modeling
2.1.1 Transient Spill Modeling
2.1.2 Steady-State Spill Modeling
2.2 Vaporization and Dispersion Modeling
2.3 Representative Problem and Boundary Condition
2.4 Reaction Modeling
2.5 Implementation of Models
2.5.1 Input and Model Set-Up
2.5.2 Output and Analysis
CHAPTER 3 – LNG SPILL/DISPERSION MODELS
3.1 Pool Model
3.2 FDS Dispersion Results
3.2.1 Total Flammable Fuel Mass and Fuel Mass Fraction
3.2.2 Lower Flammability Limit Methane Cloud
3.2.3 U-Velocity Iso-Contours and Velocity Vectors
3.2.4 Mixture Fraction-Temperature Relationship
CHAPTER 4 COMBUSTION MODEL
4.1 Combustion Modeling Results
4.1.1 Methane Cloud Ignition
4.1.2 Heat Release Rate
4.1.3 Diffusion Flame Height
4.1.4 Incident Heat Flux
CONCLUSION
5.1 Summary of Findings
5.2 Recommendations
APPENDIX
A.1 Source Files for the Fire Dynamics Simulator
A.2 Optional FDS Input Quantities
A.3 Sample FDS Input File
B.1 Implementation of a Parallel Processing Network Using MPICH2
C.1 Mixture Fraction-Temperature Scatter Plots