阶梯溢流坝自由表面掺气特性数值模拟

Numerical simulation of characteristics of free-surface aeration on stepped spillway

阶梯溢流坝作为泄水建筑物早已出现。实践发现,经过阶梯溢流坝的水流可以大量卷吸空气,从而增大水体的含氧量,因此可以利用它作为水体复氧、改善水质的措施。但对于阶梯溢流坝复氧能力的理论分析至今尚未见报道。本文引入水气两相流模型,用k ε紊流数学模型模拟计算了阶梯溢流坝自由表面掺气的特征量。计算结果与试验资料进行了对比,结果表明,计算值与实测值吻合良好,可以认为本文的数值模拟方法是可行的。这将为阶梯溢流坝复氧能力计算以及从理论上得到阶梯溢流坝的最佳布置形式提供理论基础。

Stepped spillways have existed as escape works for a long time. It is found that water can trap much air when passing through steps and then increase oxygen content in water body, so stepped spillways can be used as a measure of reaeration and to improve water quality. However, there is no reliable theoretical method for quantitative calculation of reaeration ability of the stepped spillways. By introducing air-water two phase flow model, this article uses k-ε turbulence model to calculate the characteristic variables of free-surface aeration on stepped spillway. The calculated results are fitted with the experimental results well. So the numerical modeling method in this article for calculating characteristic variables of free-surface aeration on stepped spillways is reasonable and offers a firm foundation on calculating reaeration ability of stepped spillways The simulation approach can provide a possible optimization tool for designing stepped spillways with more efficient aeration capability.