70 research outputs found
Valencia bridge fire tests: Validation of simplified and advanced numerical approaches to model bridge fire scenarios
[EN] Bridge fires are a major concern and the subject of many studies that use numerical models. However, experimental studies are still required to test the validity of these numerical models and improve their accuracy. This paper uses temperature results of the Valencia bridge fire tests carried out at the Universitat Politecnica de Valencia, in Valencia (Spain) to calibrate the fire models that constitute the first step in modeling any bridge fire event. The calibration is carried out by both a simplified approach (Heskestad and Hamada's correlation) and advanced numerical models (Computational Fluid Dynamics models built with the Fire Dynamics Simulator -FDS- software).
The Valencia bridge fire tests involved four fire scenarios under a composite bridge with Heat Release Rate (HRR) values between 361 and 1352 kW. The results show that applying Heskestad and Hamada's correlation gave good results when used within its limits of application (HRR < 0.764 MW) but did not work well beyond them, which means it would be suitable for planning reduced scale bridge fire tests but not in the analysis of real bridge fires. On the other hand, FDS provides good predictions of the temperatures and can be used to study bridge fire responses. This work is therefore an important step forward in the study of bridge fires and towards the improvement of the resilience of infrastructure networks vis-a-vis fire hazards. It also highlights the problems that can arise in fire tests in the open air, the influence of the wind being of critical importance.Funding for this research was provided by the Spanish Ministry of Science and Innovation (Research Project BIA 2011-27104). The authors are grateful to the Infrastructure and Safety departments of the Universitat Politecnica de Valencia and the City of Valencia Fire Department (Cuerpo de Bomberos de Valencia), which provided crucial support in conducting the tests.Alós-Moya, J.; Paya-Zaforteza, I.; Hospitaler Pérez, A.; Loma-Ossorio, E. (2019). Valencia bridge fire tests: Validation of simplified and advanced numerical approaches to model bridge fire scenarios. Advances in Engineering Software (Online). 128:55-68. https://doi.org/10.1016/j.advengsoft.2018.11.003S556812
An experimental and kinetic modelling study of the oxidation of the four isomers of butanol
Butanol, an alcohol which can be produced from biomass sources, has received
recent interest as an alternative to gasoline for use in spark ignition engines
and as a possible blending compound with fossil diesel or biodiesel. Therefore,
the autoignition of the four isomers of butanol (1-butanol, 2-butanol,
iso-butanol, and tert-butanol) has been experimentally studied at high
temperatures in a shock tube and a kinetic mechanism for description of their
high-temperature oxidation has been developed. Ignition delay times for
butanol/oxygen/argon mixtures have been measured behind reflected shock waves
at temperatures and pressures ranging from approximately 1200 to 1800 K and 1
to 4 bar. Electronically excited OH emission and pressure measurements were
used to determine ignition delay times. A detailed kinetic mechanism has been
developed to describe the oxidation of the butanol isomers and validated by
comparison to the shock tube measurements. Reaction flux and sensitivity
analysis indicate that the consumption of 1 butanol and iso-butanol, the most
reactive isomers, takes place primarily by H-atom abstraction resulting in the
formation of radicals, the decomposition of which yields highly reactive
branching agents, H-atoms and OH radicals. Conversely, the consumption of tert
butanol and 2-butanol, the least reactive isomers, takes place primarily via
dehydration, resulting in the formation of alkenes, which lead to resonance
stabilized radicals with very low reactivity. To our knowledge, the ignition
delay measurements and oxidation mechanism presented here for 2-butanol,
iso-butanol, and tert butanol are the first of their kind.
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