水力插板透水丁坝水流结构随透水率的变化规律研究

Study on variation law of flow structure of hydraulic flashboard permeable spur dike along with water permeability

为了研究水力插板透水丁坝水流结构随透水率变化的规律,采用ANSYS FLUENT 15. 0,基于RNG k-ε湍流模型,对不同透水率下透水丁坝周围的流场进行三维数值模拟。结果表明,透水丁坝坝体前后压差随透水率的增大逐渐减小,上游坝根处压强最大,坝头下游侧附近压强最小,坝根和坝头部位易发生水毁。回流强度随着透水率的增大逐渐减弱。当透水率达到40%时,回流基本消失,坝后为一个缓流区。不同透水率下水槽同一横断面处流速分布规律相似。随着离丁坝侧河岸距离的增加可划分为流速缓慢增大区、流速迅速增大区和流速稳定区。随着透水率的增大,主流区流速逐渐减小,坝后作用区流速逐渐增大。研究成果能够为透水率这一重要工程设计参数的合理选取提供参考,实际应用中推荐透水率为30%。

In order to study the variation law of flow structure of hydraulic flashboard permeable spur dike along with water permeability,the 3-D numerical simulations are made on the flow fields around the permeable spur dikes with different permeabilities on the basis of RNG k-εturbulent model with ANSYS FLUENT 15.0.The result shows that pressure difference between the front and back of the spur dike decreases gradually along with the increase of water permeability,while the pressure at the upstream root of the dike is the maximum and is the minimum near the downstream side of the dike head,thus water damage is prone to occur at both the dike root and the dike head.The backflow intensity gradually decreases along with the increase of water permeability.When water permeability reaches 40%,the backflow generally disappears and an area of slack water forms behind the dike.Under different water permeabilities,the distribution laws of the flow velocities at the same cross-section of flume are similar.Following with the increase of the distance from the river bank on the side of spur dike,the flow velocity can be divided into slow increase area,rapid increase area and stable area.The flow velocity in the main stream area gradually decreases along with the increase of water permeability,while the flow velocity in the effect area behind dike gradually increases as well.The study result can provide reference for reasonable selection of water permeability--this important engineering design parameter and the recommended water permeability for the actual application is 30%.