Experimental Characterization of Smoke Generators for Fire Protection

Abstract

This report summarizes experimental studies to characterize two different smoke generators with respect to the thermal and aerodynamic behavior. The measurements were performed at the test rig of the DLR in Göttingen. The test rig provides optimal environmental conditions for the studies since it is closed from the surrounding and the sidewalls are temperature-controlled in order to provide isothermal boundary conditions. Furthermore, the ventilation flows are well defined and can be adjusted very flexible. For each smoke generator, different smoke pulse programs and scenarios were analyzed. Hereto, different sensor-based and optical measurement techniques were used. The sensor-based methods include temperature probes, omnidirectional flow velocity probes, carbon-dioxide sensors as well as sensors to measure the particle size. Additionally, Laser-Doppler-Anemometry and Phase-Doppler-Anemometry are used as laser-based measurement approaches to determine the velocity and size distribution of the smoke particles. With the objective to get a better and detailed understanding of the smoke generators, the velocity and temperature distribution above the smoke outlet were captured for various points at different height levels. Further, volume flow measurements above the smoke chimney as well as for the supplying amount of carbon dioxide were performed to acquire technical parameters during a smoke pulse. Herewith, detailed quantitative validation data has been acquired successfully including averages and statistical data. In conclusion, the temperature, the velocity and the concentration fields above the smoke generators are spatially strongly inhomogeneous and temporally not constant. Generally, the studies and the corresponding results are helpful to validate the numerical model of the smoke generators. Consequently, the simulation addressingfire protection tests provide a better accuracy with a higher level of detail.