隧道横通道附近火源最不利位置的确定

Determination of the Most Unfavorable Location of Fire Source near Cross Passage in Tunnel

通过量纲分析推导横通道附近火源最不利位置与火源功率、隧道纵向风速的关系式。采用1∶20隧道模型对不同火源功率、不同隧道纵向风速时横通道附近火源最不利位置进行研究。结果表明:随着火源功率增加,横通道附近火源最不利位置保持不变,说明改变火源功率并不影响横通道附近火源最不利位置;随着隧道纵向风速增加,横通道附近火源最不利位置的最小值基本不变,而其最大值则在风速小于2.5m·s^(-1)时呈0.8次方增加趋势,在风速大于2.5m·s^(-1)时横通道附近火源最不利位置的最大值基本不变。对模型试验数据进行拟合,明确了隧道横通道附近火源最不利位置与隧道纵向风速、火源功率之间的关系,得到横通道附近火源最不利位置的无量纲计算公式。

The relational expression for the most unfavorable location of fire source near the cross passage in tunnel, heat release rate and longitudinal wind velocity was derived by dimensional analysis. Experiments were conducted with a 1 ＂ 20 tunnel model to study the most unfavorable location of fire source near the cross passage under different heat release rates and longitudinal wind velocities. Results show that the most unfavorable location of fire source near the cross passage remains unchanged with the increase of the heat release rate, which indicates that the change of heat release rate does not affect the most unfavorable location of fire source near the cross passage. The minimum value of the most unfavor- able location of fire source is almost invariant with the increase of the longitudinal wind velocity in tunnel. However, the maximum value shows an increase trend of the 0.8 power of longitudinal wind velocity when the longitudinal wind velocity is less than 2.5 m s-1, and it remains almost invariant when the longitudi- nal wind velocity is greater than 2.5 m s-1. By fitting the experimental data, the relationships between the most unfavorable location of fire source near cross passage and the heat release rate and the longitudinal wind velocity are cleared, and the dimensionless calculation formula for the most unfavorable location of fire source near the cross passage is obtained.