等壓雨屏牆風載之研究－－數值模擬與風洞實驗之比較

Wind Loads on Pressure Equalized Rainscreen Walls－A Comparison between Numerical Simulation and Experimental Results

經文獻回顧知雨屏牆藉由透風孔將外氣導入中空層可達成雨屏內外的等壓，而本研究主要是以數值計算方法來預測開放式接縫雨屏牆之等壓性能；依據先前透過風洞實驗對雨屏牆相關因子於等壓性能影響已建立基本資料，應用計算流體力學中由Navier-Stokes 方程式發展出來的商用軟體Fluent 以電腦來進行數值模擬，並將數值模擬結果與實驗作一比對。經比對後，紊流模型參數測試計算以標準k-ε 最接近實驗之趨勢，兩種方法所測得中空層壓力同樣出現均衡的狀態，證明利用雨屏透風孔方式來達成減輕雨屏牆風載行為是一致的；在自由流風速19m/ s，雷諾數約為11.8°—105 正面迎風條件下，數值模擬所預測等壓性能比實驗值略高3~4% ，建議以4% 向下修正即可接近於風洞實驗所測得雨屏牆等壓性能。

From literature review, we learned that pressure equalization of the pressure equalization rainscreen (PER) walls is achieved by the vent holes which introduce the outside air into the cavity. The studies can be studied either by experiments and/or numerical simulation. This investigation uses both approaches and compares the corresponding results for PER walls. The comparison shows that the standard k-ε turbulent model is the most accurate model. Both of numerical simulation and wind-tunnel tests show that the pressures of cavity are equal. Under the wind velocity of 19m/s with the Reynolds number of 11.8× 105, both results show consistent trends and numerical simulation predicts a 4% higher pressure equalization than that obtained by experiments on the front surface of the rainscreen and can be corrected to match the experimental results.