侧开缝对竖通道内旋转热流场影响的实验研究

为了掌握竖通道两侧开缝对于通道内热流场的影响,在一32cm(长)×32cm(宽)×200cm(高)的竖通道内进行了旋转热流场实验研究,对比了在不同热源条件下,竖通道侧开缝宽度为3.0cm和3.5cm时,侧开缝底部5cm高区域被遮挡前后通道内热流场的变化。实验结果表明,与遮挡前相比,遮挡通道侧开缝底部对火焰燃烧和热流场的运动状态都会产生影响。遮挡通道侧开缝底部区域,会在一定程度上限制外界冷空气进入通道内,从而减弱通道内的火焰旋转程度,致使燃料燃尽的耗时更长,平均火焰高度降低,其影响程度随着燃料池增大而减弱;遮挡侧开缝底部区域后,造成通道内下部区域中心轴线处的温度降低,最大影响区域在50cm高度附近,而在150cm高度以上基本没有影响;平均火焰高度与燃料池直径之比的无量纲量H/Φ与Peclet数之间的比例系数近似为1.732,并且是否遮挡侧开缝底部区域对于两者之间比例关系的影响不大。

Experimental Study on Effect of Side Gaps on Hot Flow Field Inside a Vertical Channel

Effect of side gaps on hot flow field inside a vertical channel was studied by an experiment of fire whirl in a vertical channel with the dimension 32 cm×32 cm×200 cm.Changes of hot flow field in the channel were obtained by changing fires and obstructing 5 cm at the bottom of gaps with wideth of vent 3.0 cm or 3.5 cm.From the experiment results,it can be concluded that the obstruction affected the combustion and hot fluid field.It blocked cold air flow into the channel and the fire was weakened.Then the duration of combustion became longer and the flame height was reduced.The effect became weaker with the oil pan becoming larger.Temperature at the axes and bottom of the channel became lower when the bottom of gaps was obstructed.The largest effect occurred at about 50 cm above the floor.Above 150 cm the effect was almost canceled.The ratio of averaged flame height to the diameter of fuel pool H/Φ was 1.732.The effect on the ratio was negligible whether the bottom areas of the side gaps were blocked.