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对烟囱效应消失的条件进行理论分析,建立数学模型,采用Matlab计算自然对流条件下楼梯井烟囱效应消失的临界换气量,并且利用FDS模拟9种工况进行验证。对楼梯井烟囱效应的两个关键参数,即楼梯井高度和楼梯井内部温度进行研究。设置楼梯井高度分别为7、12、17层,温度分别为15、35、55℃,比较各工况的最大体积流率和烟囱效应消失时的临界换气次数。Matlab计算结果比FDS大的原因为实际气体为可压缩气体,且不只流入下一个区。结果表明,上下开口的楼梯井体积流率和时间的关系可以用q_v=(a+b×t~(1.5))~(-1)拟合;最大体积流率主要受楼梯井内部温度影响;临界换气次数主要受楼梯井高度的影响。
Theoretical analysis of the disappearance of the chimney effect, the establishment of mathematical models, the use of Matlab to calculate the natural convection conditions of the staircase well chimney effect of the disappearance of the critical amount of ventilation, and the use of FDS simulation of 9 conditions for validation. Two key parameters of the chimney effect of the stairwells, namely, the height of the stairwells and the temperature inside the stairwells, are studied. Set the height of the stairwell 7,12,17 layers, respectively, the temperature was 15,35,55 ℃, comparing the maximum volume flow rate of each condition and the critical ventilation when the chimney effect disappears. The reason that Matlab calculates the result farther than FDS is that the actual gas is a compressible gas, and not only flows into the next zone. The results show that the relationship between volume flow rate and time can be fitted by q_v = (a + b × t ~ (1.5)) ~ (-1). The maximum volume flow rate is mainly affected by the internal temperature of the stairwell. The critical number of ventilation is mainly affected by the height of the stairwell.