外窗通风换气性能测试与流场模拟

Testing and Flow Field Simulation of External Window Ventilation Performance

采用示踪气体法(选取二氧化碳作为示踪气体)中的下降法(将一定量的示踪气体充入测试区域,在测试区域空气中示踪气体体积分数均匀后开始记录示踪气体体积分数的下降过程,通过记录数据可以计算出房间换气次数,从而得出待测外窗的通风换气性能),对上悬窗、内平开窗、外平推窗的通风换气性能进行测试。外平推窗的通风换气能力最强,上悬窗的通风换气能力最弱,内平开窗的通风换气能力居中。流体力学数值模拟结果表明,在测试期间,由于室内温度高于室外温度,在热压作用下,室内高温空气与室外低温空气在外平推窗的窗口处完成了换热。类似风帽的外平推窗,既促进了自然通风的进行,又避免了室外空气对室内气流组织的干扰。

The ventilation performance of upper hanging window, inswinging casement window and outswinging casement window is tested by the descent method, one of tracer gas methods using carbon diox- ide as a tracer gas, in which a certain amount of tracer gas is filled into the testing area, the descent process of the tracer gas volume fraction begins to be recorded af- ter uniform distribution of tracer gas volume fraction in the air in the testing area, and the frequency of ventila- tion can be calculated according to the recorded data, thus obtaining the ventilation performance of the meas- ured external window. The ventilation capacity of the outswinging casement window is the strongest, that of the upper hanging window is the weakest, and that of the inswinging casement window is moderate. The nu- merical simulation results of fluid mechanics show that during the testing, because the indoor temperature is higher than the outdoor temperature, the heat transfer between indoor high-temperature air and outdoor low- temperature air is completed at the outswinging case- ment window under thermal pressure. The outswinging casement window like hood can not only promote the natural ventilation, but also avoid the interference with indoor air from outdoor air.