風向對風壓通風影響之實驗研究

Influence of Wind Direction on the Wind-driven Natural Ventilation

陳昭瑋(Jhao-Wei Chen)

指導教授 ： 朱佳仁

國立中央大學/工學院/土木工程學系/碩士(2011年)

摘要

本研究利用風洞實驗、電子式壓力計及示踪氣體法來研究風向、室內阻礙物、室外紊流強度及走廊等參數對於建築物風壓通風量的影響，另外並探討門的開闔角度對於通風量的影響。實驗結果發現當建築物僅有單一開口時，風向角為45o時會有最大通風量，這是因為當風傾斜吹入開口時會使室內產生類似循環對流(circulation flow)的現象，使得新鮮空氣容易進入室內，混合室內空氣後再流出室外。本研究也發現在剪力通風的狀況下，室外紊流強度愈大，室內外換氣率愈大，其換氣率可用無因次通風量來預測。在貫流通風的狀況下，室內阻礙物的阻滯比愈大，通風量會愈小。且阻礙物愈靠近迎風面開口及背風面開口時，阻抗因子也會隨之增加。受室內阻礙物影響的風壓通風量可用Chu and Wang (2010)的阻抗模式及阻抗因子加以預測。另外研究結果發現當室內門闔開的角度愈大，流量係數愈大，此流量係數可做為未來預測室內有走廊之風壓通風量。

關鍵字

門的效應 ； 流量係 ； 示踪氣體 ； 風洞實驗 ； 風壓通風 ； 自然通風

並列摘要

This study used wind tunnel experiments and tracer gas technique to investigate the influence of wind direction and internal obstacle on the wind-driven ventilation rate of a single-zone building and building with corridor. In addition, external turbulence intensity and the door effect was also examined in this study. The results demonstrate that the maximum ventilation rate occurs at wind direction equals to 45o for building with single-sided opening. It is because the fresh air is easier to enter the building opening when there is an oblique angle between the opening façade and wind direction. This study also found that the ambient turbulence can enhance the shear-induced ventilation rate when the wind direction is parallel to the opening. In addition, the experimental results reveal that the cross-ventilation decreased as the blockage ratio of internal obstacles increased, or the distance between the obstacle and opening decreased. The ventilation rate and resistance factor can be predicted by the resistance model from Chu and Wang (2010). Finally, the results of fan technique display that the discharge coefficient is a function of the door angle, but is independent of the Reynolds number. The concentration variation in the corridor can be predicted by a continuous ventilation model.

並列關鍵字

Tracer gas technique ； Discharge coefficient ； Wind tunnel experiment ； Natural ventilation ； Wind direction

參考文獻

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