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- Aircraft cabin air flow (1)
- Burning behaviour (1)
- Bus interior materials (1)
- Bus materials (1)
- Computational fluid dynamics (1)
- Cone calorimeter (1)
- DIN tube furnace (1)
- FTIR spectroscopy (1)
- Fire (1)
- Furniture (1)
- Gas mixtures (1)
- Large scale (1)
- Model validation (1)
- Reference values (1)
- Smoke toxicity (1)
- Spill evaporation (1)
Organisationseinheit der BAM
Dangerous goods are transported as air freight in commercial aircrafts. Using plastic jerrycans or plastic containers, liquids or gases can escape by leakage or permeation effects. Prior research by the German Federal Institute for Materials Research and Testing (BAM) showed that the lower explosion limit can be reached when transporting dangerous goods in sea-freight containers under normal transportation situations. This motivated the presented study of the transportation situation of dangerous goods in cargo compartments of commercial airplanes. The scope of this paper is to present the experimental method used for validating a numerical model for CFD (Computational Fluid Dynamics) simulations. The CFD model will be used in a future study to evaluate the potential risk from transporting dangerous goods.
The objective of this paper is to present the model mock-up of an aircraft cargo compartment and some examples of three dimensional velocity profiles of the air flow in the mock-up. The velocity profiles are calculated using numerical simulations and measured by Laser-Doppler-Anemometry (LDA) experiments. The mock-up is a generic model of a wide-body aircraft lower deck cargo compartment in a 1:10 scale. Geometry, air exchange rates and inlet as well as outlet flow conditions in the cargo compartment are modeled using realistic boundary conditions. The commercial CFD (Computational Fluid Dynamics) code ANSYS CFX 14 is used for numerical flow simulations applying RANS (Reynolds-Averaged-Navier-Stokes) equations and turbulence models. The turbulence models studied are the renormalization group k-ε-model (RNG), the Reynolds-Stress model by Launder, Reece and Rodi (LRR) and the SST-k-ω-model by Menter (SST).
The flow measurement with LDA in the mock-up of a cargo compartment proves to be a feasible method for producing data to validate CFD simulations. Qualitative evaluation of the results shows a good overall agreement between numerical and experimental results. The experimental validation indicates that the implemented CFD model is capable of reproducing the flow situation in the model mock-up.
About 80 % of all fire fatalities in Germany occur in fires in homes1. UK statistics show that living and bed room fires are more often responsible for fatalities than kitchen fires although kitchen fires occur much more often2. It has been known for some time that modern materials tend to burn differently from older materials and it has been acknowledged that the amount of combustible plastics in homes has increased significantly over the last decades3-7. To investigate the influence of modern furniture and ventilation conditions of fires in homes a series of four large scale tests in two living rooms with adjacent rooms was performed by BAM and the Frankfurt fire service8. Two living rooms, one with older furniture and one with modern furniture were tested twice each. Each test started with the ignition of a paper cushion on an upholstered chair. The influence of modern materials on the fire development was investigated as well as the influence of the ventilation on the fire development. Two tests with closed windows and two tests with open windows were performed. Temperatures were measured in the living rooms and the adjacent rooms, gas compositions were measured in the adjacent rooms and videos were taken in all rooms. The ventilation as well as the different materials influenced the fire development regarding temperatures in the rooms and smoke production and composition significantly. The fire in the living room with modern furniture developed faster than the same setting with older furniture. More ventilation (open window) led to higher temperatures in the rooms and faster fire development as well. Smoke gas composition was measured in the adjacent rooms to assess the positive effect for a person being in the adjacent room and not in the room of fire origin. In all settings an upholstered chair was the first burning item. The modern upholstered chair was investigated in three pre-experiments under different conditions to enhance the understanding of the living room fires. The measured mass losses and derived mass loss rates have been used for numerical modelling of the pre-experiments.
In recent years, fire safety requirements for bus interior materials have been increased and introduced into international regulations. Fire safety requirements for the burning rate, melting and dripping behaviour of interior materials already exist for many years. However, it remains unclear to what extent the release of smoke, combustion products and their toxicity should be limited. Therefore, a research and development project 82.0723 funded by BASt (Federal Highway Research Institute) was initiated to develop a simplified procedure for testing the toxicity and smoke development in case of fire of interior materials used in buses. The scope of the research included calculations to assess the toxicity of fire gases and the derivation of specifications for the formation of practicable limit values for smoke toxicity. Further investigations are needed to derive these limit values for smoke toxicity in order to be applicable for real fire scenarios in buses.
In this paper, we investigate the evaporation mass flow originating from spills of gas-oline. Large spills of gasoline may form during partial or complete roof sinkings or inthe case of perforations at various deck fittings at external floating roof tanks usedfor the storage. Additionally, spills may form in the retention area in the case of leak-ages at pipes or at the hull. The aim is to predict the order of magnitude of real-scaleevaporation mass flow. The determined evaporation mass flows will be used in arelated project as input values for subsequent dispersion modeling in the vicinity ofthe tanks. This is relevant for questions of fire and explosion protection as well as forenvironmental protection aspects in tank farms or refineries, which use externalfloating roof tanks. The measurements presented in this paper were compared withpredictions by empirical models and investigations of evaporations from small floorspills, round-bottom flask, or from Petri dishes published in the literature. The maingoal of this paper is to test the applicability of empirical models to provide reasonableevaporation mass flows as input for CFD dispersion simulations.
Although fire safety regulations for buses have been adapted in recent years regarding, for example, fire detection and engine fire suppression systems, the changes in regulations for bus interior materials are minimal. A comparison of fire safety regulations for interior materials in other transport sectors for trains, ships or aircraft reveals a much lower level of requirements for bus materials. Although repeated bus accidents as well as fire statistics show the danger a bus fire can pose to passengers.
In particular, the combination of a fire incident and passengers with reduced mobility led to severe disasters in Germany and other European countries. To enhance the fire safety for passengers, the interior bus materials are crucial as the fire development in the bus cabin determines whether escape and rescue is possible. Against this background, bus interior materials were tested in different fire test scenarios. Measurement of a wide variety of parameters, for example, the mass loss, ignition time, smoke gas composition, heat release rate among others were carried out. Tested materials complied to the newest set of requirements. For this purpose, interior materials and their components had to be identified according to their chemical structure. Parts of the tests were funded by BASt (Federal Highway Research Institute) in the project 82.0723/2018. Experimental results show reaction-to-fire behaviour which lead to very limited times for escape and rescue in case of fire in a bus cabin. Based on the studies on fire behaviour and toxicity assessment, recommendations for improved fire safety regulations for interior materials could be made.