Jonathan Wahlqvist

Detection of a typical arson fire scenario – comparison between experiments and simulations

Abstract in Undetermined Between one and two school fires occur in Sweden every day. In most cases, arson is the cause of the fire. The most severe fires generally start outside the building and spread up along the facade and into the attic through ventilation openings in the eaves. Linear heat detectors can be placed on facades to detect these types of fires. Such devices detect fire when short-circuited at a specific temperature. In this article, an attempt to simulate linear heat detectors is presented. Data from small-scale and full-scale experiments are compared with these simulations. The small-scale experiments and simulations demonstrate that the cable failure model in Fire Dynamics Simulator can be used to predict detection in linear heat detectors that use short-circuiting as the means of signaling an overheated condition. The full-scale experiments provide a measure of the uncertainties involved, as well as the possibility of using simulations of linear heat detectors in a fire engineering design. (Less)

Room-Fire Characterization Using Highly Range-Resolved Picosecond Lidar Diagnostics and CFD Simulations

In fire safety engineering, the use of computational fluid dynamics (CFD) allows for detailed multidimensional calculations of important parameters, for example, temperature. However, increasing use of CFD models puts requirements on experimental validation, a challenge for many measurement techniques under harsh fire conditions. In this work, laser-based picosecond light detection and ranging (ps-lidar) was used for remote measurements in a ½-scale ISO 9705 room containing either a methanol pool fire or a methane diffusion flame. Spatially resolved Rayleigh thermometry was conducted in the vertical door plane and in a horizontal plane inside the room. Temperatures obtained by ps-lidar are compared with values from thermocouples located in the doorway as well as results from CFD simulations. The technique allows for quantitative thermometry provided that minimal particle scattering interferences are present. Measurements of detailed distributions of temperature and particulates clearly demonstrate the potential of ps-lidar for diagnostics in large-scale combustion.