竖井横截面积对隧道自然排烟效果影响的实验研究

在1∶6尺寸城市隧道实验台上开展了一系列试验,研究了不同火源功率、竖井横截面尺寸条件下隧道自然排烟竖井的排烟效果。结果表明,竖井的横截面尺寸直接影响竖井内烟气运动的驱动力大小,从而影响排烟效果。在一定的火源功率下,竖井横截面积过小时难以有效排出烟气,面积过大将会产生过于强烈的烟囱效应,导致排烟口下方空气被直接排出,排烟效果显著下降;竖井横截面积一定时,在不同的火源功率下,竖井放置方式同样影响竖井的排烟效果。

Experimental investigation on influence of shaft cross-sectional area on natural ventilation in urban road tunnel fires

Experiments were conducted in a small-scale model tunnel with a scale ratio of 1:6. The purpose of this paper is to investigate the effect of shaft cross-sectional geometry on the natural ventilation in urban road tunnel fires under different heat release rates. Results show that the dimension of shaft cross-section has a significant effect on the driving force of the smoke movement. In a certain heat release rate with a small area of shaft cross-section, the mass flow rate exhausted through shaft is not enough to effectively discharge the smoke, while a too large area will lead to too strong stack effect, and the ambient fresh air beneath the smoke layer will be exhausted directly. Moreover, with a certain area, the placement of the shaft also affects the smoke exhaust efficiency under different heat release rates.