Using FDS to Investigate the Effect of Positive Pressure Ventilation for Fighting Wind-driven High-rise Fires

• Main Authors: WANG, TZU-YU, 王子俞
• Other Authors: I, YET-POLE
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/3u2e9z

碩士 === 國立雲林科技大學 === 環境與安全衛生工程系 === 106 === Wind can create extremely dangerous environments when it impacts on high-rise building fires. According to the statistics of the New York Fire Department, 14 wind-driven high-rise building fires between 1980 and 2008 caused unfortunate consequences of 11 civilians and 5 firefighters death. Positive Pressure Ventilation (PPV) can effectively reduce fire temperature, eliminate smoke, improve visibility and increase the safety of fire escapers and rescuers. However, the efficacy of PPV is influenced by various parameters, such as building structure layouts, wind conditions, and PPV deployment configurations. Therefore, this study employs the Fire Dynamics Simulator (FDS) to simulate the high-rise building fire and test the performance of PPV strategy under the influence of the aforementioned relevant parameters. The study results show that when a single fan is used for PPV, it can effectively block the smoke from entering the stairwell and reduce the temperature of the fire. However, when the external wind speed reaches 5 m/s or more (test wind speed ranges from 0 to 10 m/s, the warning wind speed is 4.5 m/s according to the NIST), it will have a serious impact on the fire scene, and will case the PPV strategy failure by using a single PPV. Therefore, this study enhances the PPV efficiency through two fans. It is found from the research that the effects of lowering the fire temperature and eliminating the smoke are significantly improved when the fans are used in parallel. Finally, after using the parallel fans with the fire resistant metal rolling gates inside the building, one can effectively increase the air impermeability of the fire floor, while guiding the airflow to leave the interior of the building through a pre-planned path. In the same time, one can significantly increase the ability of PPV to eliminate smoke, reduce fire temperature and improve visibility; the temperature is controlled to near ambient and the visibility is maintained above 30 meters at the important aisles. Therefore, in the absence of mechanical ventilation inside a building fire, a PPV strategy implemented by the firefighters can ultimately provide a safer environment for the personnel inside the fire.