应用LK k-ε模型的气承式充气膜结构风荷载和风环境研究

Study on wind load and wind environment of the air-supported membrane structures using LK k-ε model

首先以6m立方体建筑绕流为例,对计算风工程中常用的RANS模型进行了评估,得出LK k-ε模型在同时预测风压和流场方面具有较好的效果。之后应用LK k-ε模型对不同矢跨比的三个典型气承式充气膜结构在不同风向角下的风荷载和周围风环境进行了研究。计算结果显示随着风向角的增加,气膜顶部的极大负压区域和极大负压值都明显增大,在来流为90°时(风向与气膜长边垂直)达到最大,且在该风向角下,随着气膜矢跨比的增加,顶部负压也明显增大。综合来看,气膜结构的抗风设计以极大负压为主,极大负压区域主要出现在气膜的顶部和四个拐角位置。以风速比为指标对气膜周围风环境的研究表明,在气膜的拐角附近和下游某些区域都出现了明显的来流加速现象。

The RANS models which are commonly used in wind engineering field were evaluated by simulating the flow around 6 m cubic. It is found that the LK k-ε model is more effective on the prediction of both the wind pressure and the flow field. Then the wind load and wind environment of three typical air-supported membrane structures with different risespan ratios in different wind directions were investigated by using the LK k-ε model. The results show that the maximum negative pressure area and value at the top of the membrane structure increase significantly as the increase of the angle of wind direction,and reach the maximum when the angle of wind direction is 90 degree( the wind direction is perpendicular to the long edge of the structure). Moreover at this wind direction,the negative pressure at the top increases significantly with the increase of the rise-span ratio. In general,the wind resistance design of air-supported membrane structure is mainly based on the maximum negative pressure,and the maximum negative pressure area usually appears at the top of the structure and its four corners. Taking the wind speed ratio as the index,the study on the wind environment around the airsupported membrane structure indicates that there is obvious flow acceleration near the corner of the structure and at some downstream areas behind the structures.