侧墙掺气坎水力特性的数值模拟

采用数值模拟的方法,研究了侧墙掺气坎的水力特性。与试验结果对比分析表明,用紊流数学模型来模拟泄水道反弧末端侧墙掺气坎的水力特性是可行的。数值模拟表明,不论是跌坎上游侧墙贴角,还是跌坎下游侧墙突扩,当侧墙掺气坎尺寸较大时,均会出现反弧末端过坎射流落水点下游两侧水翅串顶的不利流态。其控制条件为底空腔和侧空腔的相对长度,当侧空腔长度大于底空腔长度时,较长的侧空腔就为跌落至底板的紊动水流提供了流动通道,会出现不利流态,反之,当侧空腔长度较小时,能形成较好的流态。过坎水流落水点下游的流态对跌坎上游侧墙贴角尺寸较为敏感,相对而言,对跌坎下游侧墙突扩尺寸就不那么敏感。数值模拟也证实,采用尺寸较小的侧墙掺气坎,形成较小的侧空腔,能满足进行侧掺气的同时具有较好的流场水力特性。

Numerical Simulation of Hydraulic Characteristics of Lateral Direction Aerators

The paper studied the hydraulic characteristics of the side wall aerator by using the numerical simulation.The comparison between the study results and the test results indicates that it is feasible to simulate the hydraulic characteristics of the aerators of the side walls at the end of ogee section in spillway by using the mathematic model of the turbulent flow.The numerical simulation shows that either the lateral deflector aerator or the expanding of the side walls could result in a bad flow pattern when the measurement of the side wall aerator becomes bigger.The key condition is the relative lengths of the bottom and side air chambers.When the length of the side air chamber is longer than the bottom's,the longer side air chamber provides passage for turbulent flow falling toward the base board and disadvantageous flow pattern will appear.On the contrary,when the length of the side air chamber is shorter,a better flow pattern occurs.The flow pattern is more sensitive to the dimensions of the lateral deflector aerator than the expanding aerator.It is also proved by numerical simulation that the small-sized lateral direction aerator,which brings a small side air chamber,can satisfy the side air entrainment and better flow characteristics.