Zhaozhi Wang

Coupled Fire/Evacuation Analysis of the Station Nightclub Fire

In this paper, coupled fire and evacuation simulation tools are used to simulate the Station Nightclub fire. This study differs from the analysis conducted by NIST in three key areas; (1) an enhanced flame spread model and (2) a toxicity generation model are used, (3) the evacuation is coupled to the fire simulation. Predicted early burning locations in the full-scale fire simulation are in line with photographic evidence and the predicted onset of flashover is similar to that produced by NIST. However, it is suggested that both predictions of the flashover time are approximately 15 sec earlier than actually occurred. Three evacuation scenarios are then considered, two of which are coupled with the fire simulation. The coupled fire and evacuation simulation suggests that 180 fatalities result from a building population of 460. With a 15 sec delay in the fire timeline, the evacuation simulation produces 84 fatalities which are in good agreement with actual number of fatalities. An important observation resulting from this work is that traditional fire engineering ASET/RSET calculations which do not couple the fire and evacuation simulations have the potential to be considerably over optimistic in terms of the level of safety achieved by building designs.

Evacuation analysis of 1000+ seat Blended Wing Body aircraft configurations: Computer Simulations and Full-Scale Evacuation Experiment

Blended Wing Body (BWB) aircraft with around 1000 passengers and crew are being proposed by aircraft manufacturers. This type of aircraft configuration is radically different from conventional tube type passenger aircraft and so it is essential to explore issues related to both fire and evacuation for these configurations. Due to both the large size and the unusual nature of the cabin layouts, computer simulation provides the ideal method to explore these issues. In this paper we describe the application of both fire and evacuation simulation to BWB cabin configurations. The validity of the computer evacaution simulations is also explored through full-scale evacuation experiments.

Numerical investigation of fires in small rail car compartments

In this article, an enhanced flame spread model is used to simulate a rail car compartment fire test. The model was found to be able to reproduce the following experiential results: the predicted progressive burning locations are consistent with the experimental record; the predicted temperatures and heat fluxes at various locations essentially follow the measured trends; and the predicted onset of flashover is within 9% of the measured time of 180 s. The sensitivity of the predicted time to flashover is assessed using 18 fire scenarios in which the uncertainties in the measured material properties are systematically examined. The time to flashover is found to be most sensitive to changes in seat material properties. For the investigated rail car compartment, the impact of porosity of the overhead luggage rack structure on time to flashover is also examined and found to be significant for small ignition source fires. Language: en

Simulating smoke transport in large scale enclosure fires using a multi-particle-size model

In Computational Fluid Dynamics (CFD) based fire simulation, the particle laden smoke is usually assumed to be in a gaseous state. This is due to the assumption that most of the smoke particles have diameters less than about 2.0 µm and so their settling velocities can be ignored compared with the intensive turbulent fire gas flow. This simplification can lead to severely under-predicted smoke levels in the lower layer at remote locations from the fire source. This problem is addressed in this paper through the development of a Multi-Particle-Size model which takes into consideration the uneven mass size distributions of smoke particles. The model divides the smoke particles into three groups with various diameter ranges. The transport of smoke particles in each group is represented by a governing equation, in which the gravitational force is addressed by adding a correction into the convection term. The efficiency of the model to reproduce smoke transport is demonstrated by simulating a large scale PVC-cable fire experiment conducted in a long corridor. Compared with a conventional smoke transport model, the new model is shown to be better able of reproducing the measured experimental smoke data and the recorded visibilities.

Fire and evacuation analysis in BWB aircraft configurations: Computer simulations and large-scale evacuation experiment

How long would it take to evacuate a blended wing body (BWB) aircraft with around 1,000 passengers and crew? How long would it take an external post-crash fire to develop non-survivable conditions within the cabin of a BWB aircraft? Is it possible for all the passengers to safely evacuate from a BWB cabin subjected to a post-crash fire? These questions are explored in this paper through computer simulation. As part of project NACRE, the airEXODUS evacuation model was used to explore evacuation issues associated with BWB aircraft and to investigate fire issues, the CFD fire simulation software SMARTFIRE was used. The fire and evacuation simulations were then coupled to investigate how the evacuation would proceed under the conditions produced by a post-crash fire. In conjunction with this work, a large-scale evacuation experiment was conducted in February 2008 to verify evacuation model predictions. This paper presents some of the results produced from this analysis.

Assessing levels of hydrogen cyanide in fire experiments using a generalized correlation

A generalized relationship between the normalized yields of carbon monoxide and hydrogen cyanide for nitrogen-containing materials has recently been derived. This correlation is used in the current study to analyze experimentally derived hydrogen cyanide data from three sets of fire tests. For a reduced-scale compartment fire test, the yields of hydrogen cyanide with varied equivalence ratios and the transient hydrogen cyanide concentrations are estimated; for a series of room-corridor sofa fire tests, the extremely high hydrogen cyanide level observed is demonstrated to be a realistic result and a hydrogen cyanide yield value of 0.047 g/g is suggested for this sofa in post-flashover fires for fire safety assessments; and finally, for a series of smoke chamber tests with polyurethane, possible causes for the failure to detect hydrogen cyanide are suggested. Language: en