市政供热有限空间通风防护技术数值模拟

为有效指导市政供热有限空间机械通风现场施工, 保障作业人员安全, 采用CFD方法对通风过程进行数值模拟计算, 研究通风过程中有限空间内部流场、温度场、氧气体积分数、二氧化碳体积分数的分布规律.结果表明：进行机械通风时, 相对于供热管沟, 小室内新旧空气替换较快, 温度下降及气体体积分数恢复都较为迅速；供热管沟内风流场受内部结构和热升力的影响, 风流主要沿管沟底部流动, 管沟顶部空气速度较小、温度较高、氧气和二氧化碳体积分数恢复较慢.针对所研究的管沟, 通风量为6 000、8 000、10 000、12 000、14 000 m3·h-1时, 最小通风时间应分别不小于45、32、22、15、10 min.实际作业中应以管沟中段顶部空气中的氧气体积分数作为衡量通风效果的关键参数
In order to provide effective guidance to the construction and to ensure the safety of workers, numerical simulations were performed on distributions of airflow, temperature fields, oxygen content, and carbon dioxide content during the process of mechanical ventilation using the CFD software. The results demonstrated that, in the course of mechanical ventilation, compared with the pipe trench, the recovery of environmental condition such as temperature and gas volume fraction including oxygen and carbon dioxide were more rapid in the heat chamber. The air flow was mainly along the bottom of the pipe trench and the air velocity at the top of the pipe trench was small because of the internal structure and thermal lift in the pipe trench. For the pipe aforementioned, when the ventilation volume was 6 000, 8 000, 10 000, 12 000, 14 000 m3·h-1, the minimum ventilation time needed should not be less than45, 32, 22, 15, 10 minutes, respectively. In practical operation, oxygen content at the top of the central part of the trench should be regarded as the key parameter to evaluate the ventilation effects