單側雙開口建築物通風之實驗研究;Experimental Study of Wind-dreven Ventilation with Two Openings on a Single Wall

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Title:	單側雙開口建築物通風之實驗研究;Experimental Study of Wind-dreven Ventilation with Two Openings on a Single Wall
Authors:	蔡易廷;Tsai,Yi-ting
Contributors:	土木工程學系
Keywords:	自然通風;風壓通風;單側通風;風洞實驗;示踪劑濃度衰減法;Natural ventilation;Wind-driven ventilation;Single-sided ventilation;Wind tunnel experiment;Tracer gas technique
Date:	2015-07-20
Issue Date:	2015-09-23 10:05:25 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究使用風洞實驗及示踪氣體之濃度衰減法來量測單側雙開口建築物之通風量，且探討風速、風向和開口大小對通風量之影響。由實驗結果發現當風向平行於開口時，無因次化之通風量不會隨著室外風速及開口面積增加而變化。此外，當風向角為0度及67.5~180度時，兩開口處之壓力係數差異很小，室內之擾動風壓大於兩開口處之壓差，所以室內、外之空氣交換是藉由擾動風壓主導，通風量之預測不能藉由孔口方程式來做預測。當風向角介於22.5~45度時，兩開口處之壓差遠大於室內擾動風壓，所以此情況為兩開口之壓差驅使室內外之空氣流通，因此可代入傳統的孔口方程式來做通風量之預測。除此之外，本研究還有探討室內隔間對建築物之通風影響，由研究結果發現當風向角為0~90度時，有室內隔間之建築物通風量會小於無室內隔間之建築物通風量，通風量之預測可藉由Chu and Wang (2010)的阻抗模式及阻抗因子來做預測。當風向角介於112.5~180度時，通風量將不再受室內隔間牆所影響，換氣量接近無室內隔間牆建築物之換氣量。;This study used wind tunnel experiments to investigate the influence of wind speed, direction and opening size on the wind-driven ventilation with two openings on a single wall. The exchange rates Q across the openings were systemically measured by tracer gas decay method. The experimental results indicate that the dimensionless exchange rate, Q* = Q/UHA, of shear-induced ventilation (wind is parallel to the openings) is independent of the wind speed UH and opening area A. Furthermore, the exchange rate cannot be predicted by the orifice equation when the wind direction equals to 0o and 67.5o~180o, because the time-averaged pressure difference across the opening is close to zero. The fluctuating pressure across the building openings will entrain air across the opening, and the exchange rate is proportional to the root-mean-square of fluctuating pressures. For wind direction equals to 22.5o ~ 45o, since the pressure difference is much larger than fluctuating pressure, the ventilation is dominated by the pressure difference across the openings. In addition, this study also investigates the single-sided ventilation for buildings with internal partition. The exchange rate for building with internal partition is smaller than building without internal partition for wind direction equals to 0o ~ 90o. When wind direction equals to 112.5o ~ 180o, the exchange rate is independent of the internal partition wall. The ventilation rates with the internal plate can be predicted by a modified version of the resistance model of Chu and Wang (2010).
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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