The effect of tunnel height on critical ventilation velocity in tunnel fires

• Main Authors: Yi-Kai Yan, 顏翊凱
• Other Authors: Kuang-Chung Tsai
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/97616742654653509251

碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程研究所 === 102 === Ventilation is an effective method for controlling smoke during a tunnel fire. The “critical ventilation velocity” ucr is defined as the minimum velocity at which smoke is prevented from spreading under longitudinal ventilation flow in tunnel fire situations. Many theoretical, experimental and numerical researches have investigated the effect of different geometries of cross section of tunnel on the ucr. Most of the researches discussed the tunnel width, and tunnel height was not discussed. This study used an 1:20 small-scale tunnel (8 m in length, 0.3 m、0.4 m、0.5 m、0.6 m、0.8 m in height and 0.6 m in width) to understand the influence of tunnel height on critical ventilation velocity. Gasoline in square pans (2.7 kW、5.4 kW、8.1 kW、10.8 kW、13.5 kW for free burning) was used as fire source. There are two ways to determine the ucr. Results show that the tunnel height significantly influences the smoke flow in tunnel fire and ucr. When the tunnel aspect ratio is greater than 1, the flow velocity was higher in tunnels with lower heights. However, when the tunnel aspect ratio is less than 1, the flow velocity was lower in tunnels with lower heights..