虹吸井溢流堰跌水掺气浓度数值模拟探索研究

Study on numerical simulation of falling water aeration concentration of siphon-well overflow weir

滨海电厂排水虹吸井溢流堰跌水掺气是造成受纳海域泡沫污染的重要因素之一,掌握虹吸井段跌水掺气浓度对研究排水消泡措施具有重要意义。鉴于掺气试验物理模型相似性、复杂水流条件下掺气浓度测量精度、模型试验周期和成本等问题,虹吸井物理模型试验具有一定的局限性。随着计算流体力学软件发展成熟,数值模拟方法逐渐成为研究复杂流动的有效工具,且可进行多方案分析计算,对物理模型试验具有指导、补充作用。本文采用FLUENT软件结合VOF模型与标准k-ε模型对虹吸井溢流堰跌水掺气问题进行了数值模拟。通过与物理模型试验结果的对比分析,显示有较好的拟合性。在此基础上,计算分析了虹吸井溢流堰下游不同过流量、不同潮水位和不同跌水高度的掺气浓度变化。计算结果证明此方法可在一定程度上反映掺气浓度的变化规律,并可为不同工程方案掺气程度对比研究提供依据。

As the falling water aeration of the drainage siphon-well overflow weir for coastal power plant is one of the important factors to cause the foam pollution in the receiving sea area, grasping the falling water aeration concentration in the section of siphon-well has an important significance to study the drainage defoaming measures. In view of the problems, such as similarity of the physical model of aeration test, the measurement accuracy of aeration concentration under complicated flow conditions, the model test cycle and cost, etc., certain limitations are there for the physical model test of siphon-well.Along with the development of the software for computational fluid dynamics, the numerical simulation method gradually becomes an effective tool for the study of complicated flow, which can be adopted to make multi-scheme analysis and calculation, and then has a guiding and supplementary role for the physical model test. With FLUENT software combined with VOF model and standard k-ε model, a numerical simulation is made herein on the falling water aeration of overflow weir for siphon-well. Through the comparative analysis with the test result from the physical model, a better fitting is exhibited. On the basis of this, the variations of the aeration concentration at different overflow-discharges, different tidal levels and different heights of falling water are calculated and analyzed. The calculation result demonstrates that the variation law of aeration concentration can be reflected by this method to a certain extent, and then a basis for the comparative study made on aeration degree for different engineering schemes can be provided as well.