山區地形中風速壓剖面之檢討

Assessment of Wind Velocity Profiles in Mountain Areas

本研究針對現行風力設計規範中有關山區三個基本特殊地形（懸崖、山脊與山丘）之風場進行探討，據以建立相應之風場資料庫，繼而評估規範中建議風速壓剖面之適宜程度。研究中先首應用風洞試驗量取相對低雷諾數情況下模型地形之風場，以為數值模擬結果驗證之基準。待風場數值模式確立後，再以系統化的數值模擬獲取與實際情況相符合的高雷諾數風場資料。除了細部檢視此三種特殊地形之風況特性外，本研究再藉數值結果與規範中建議風速剖面飽滿程度之比較檢討其間之差異。主要結果顯示，在山脊與山丘的情況，其背風面會因分流的發生而導致迴流的現象，而此非恆定流的風速變化呈現近似常態分佈的形式。此外，研究中亦發現規範中有關此三個基本特殊地形之設計風速壓剖面，在部份的區域中規範的建議的風速壓剖面上低估之情形。

The flow characteristics in cases of an escarpment, a ridge and a hill were investigated systematically to establish the wind flow data base and to assess the validity of the related code in terms of velocity pressure profiles. In the study, velocity profiles of models were measured in a wind tunnel and the results were used to confirm the accuracy of the numerical simulations. After the applicability of the numerical method was assured, a series of numerical simulations were performed to predict the flows of the three unique topographical cases. Accordingly, not only the flow features were examined in detail but the validity of the code suggestions was evaluated. Major results show that in the ridge and hill cases, reverse flow exists in the leeward region due to the occurrence of separation and the local velocity fluctuations behave in a manner close to a normal distribution. Moreover, the velocity profiles suggested by the present code appear somewhat non-conservative.