Abstract
Combustible liquids are often present in large quantities in industrial facilities and in transportation. Leaks, vessel ruptures, transportation accidents and terrorist attacks involving liquids may lead to large scale fire incidents. Analyses of such incidents are needed in the safety analyses of nuclear power plants and other critical infrastructure. However, large scale incidents may be outside the area of validity of empirical models. Development and validation of numerical simulation methods are therefore needed.
This thesis has two objectives. The first is to develop and validate spray boundary conditions that can be used to model spray injection of water mist systems or for modeling liquid dispersal. The second is to predict burning rates of liquid pool fires starting from first principles. Large eddy simulation is used for the Eulerian gas phase solution and Lagrangian particle tracking for the sprays.
The spray model is developed and validated using data from experiments on highpressure water mist nozzles and liquidfilled missile impacts. Suitable droplet size distributions and initial velocities for use in spray simulations are determined from experimental data. The spray structure and entrainment into the sprays are predicted with reasonable accuracy. The conclusion is that liquid dispersal from missile impacts can be simulated using the same spray models as for water mist sprays.
The burning rate of the liquid pool is calculated on the basis of vapor pressure and a mass transfer calculation at the liquid surface. One dimensional heat transfer by conduction and radiation within the liquid is considered. Effective absorption coefficients are determined for use with a onedimensional radiation transport equation. An enhanced thermal conductivity model accounts for indepth convective heat transfer. The conclusion is that inclusion of spectrally resolved radiation calculations and of lateral convection may be necessary for predicting the temporal development of the burning rate.
Finally, the models are applied to the fullscale simulation of an airplane impact on a nuclear island. The predicted fireball lifetimes and sizes compare favorably with available empirical correlations. A significant amount of the fuel involved accumulates on the surfaces around the impact point.
This thesis has two objectives. The first is to develop and validate spray boundary conditions that can be used to model spray injection of water mist systems or for modeling liquid dispersal. The second is to predict burning rates of liquid pool fires starting from first principles. Large eddy simulation is used for the Eulerian gas phase solution and Lagrangian particle tracking for the sprays.
The spray model is developed and validated using data from experiments on highpressure water mist nozzles and liquidfilled missile impacts. Suitable droplet size distributions and initial velocities for use in spray simulations are determined from experimental data. The spray structure and entrainment into the sprays are predicted with reasonable accuracy. The conclusion is that liquid dispersal from missile impacts can be simulated using the same spray models as for water mist sprays.
The burning rate of the liquid pool is calculated on the basis of vapor pressure and a mass transfer calculation at the liquid surface. One dimensional heat transfer by conduction and radiation within the liquid is considered. Effective absorption coefficients are determined for use with a onedimensional radiation transport equation. An enhanced thermal conductivity model accounts for indepth convective heat transfer. The conclusion is that inclusion of spectrally resolved radiation calculations and of lateral convection may be necessary for predicting the temporal development of the burning rate.
Finally, the models are applied to the fullscale simulation of an airplane impact on a nuclear island. The predicted fireball lifetimes and sizes compare favorably with available empirical correlations. A significant amount of the fuel involved accumulates on the surfaces around the impact point.
Original language  English 

Qualification  Doctor Degree 
Awarding Institution 

Supervisors/Advisors 

Award date  19 Jan 2018 
Place of Publication  Espoo 
Publisher  
Print ISBNs  9789526077840, 9789513885991 
Electronic ISBNs  9789526077857, 9789513885984 
Publication status  Published  2017 
MoE publication type  G5 Doctoral dissertation (article) 
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Keywords
 fireball
 pool fire
 spray
 plane crash
Cite this
Sikanen, T. (2017). Simulation of transport, evaporation, and combustion of liquids in largescale fire incidents: Dissertation. Aalto University. http://www.vtt.fi/inf/pdf/science/2017/S169.pdf