淤积工况下薄壁三角堰流量特征研究

Performance of Triangular Crested Weir under Impact of Sediment Deposition

【目的】探究淤积工况下薄壁三角堰的流量特征。【方法】利用计算流体力学软件FLUENT 19.0,结合室内试验,模拟薄壁三角堰渠道从无淤积至淤满过程中9个淤积工况下的过堰流场,分析流场内的流量、流速和水位变化,探讨渠道流量特征随淤积厚度的变化情况。【结果】模拟流量与理论流量、实测流量数值吻合,渠道内流速分布符合流速分布一般规律,证明模拟结果准确可靠;当理论流量为0.2210 L/s时,随着堰前淤积的加厚,模拟流量与实测流量呈无规律的波动变化,波动范围为理论流量的-0.45%~8.60%;当理论流量为0.2210 L/s时,对比无淤积和淤积工况下的堰前水面曲线,模拟与实测曲线均在近堰板处出现不同程度的的水位壅高,高度随淤积厚度的增加而波动上升。【结论】淤积会使堰前水位壅高且增大薄壁三角堰过流能力,而堰流公式中缺少适应这种变化的修正参数,导致生产中所得理论流量偏小。

【Objective】Weir is a device to measure water flow in open channels.Its accuracy and robustness depend on many factors.In this paper,we studied the performance of the triangular crested weir as impacted by sediment deposition in open channels.【Method】The study was based on computational fluid dynamic modelling.We simulated water flow under nine conditions ranging from no sediment deposition to full sediment deposition using the software FLUENT 19.0.The simulated results were verified against experimental measurements.【Result】①The simulation results were reliable and robust as comparison with experimental data showed that the simulated water flow rate and velocity distribution in the channels agreed well with those experimentally measured.②When the theoretical flow rate was 0.2210 L/s,the simulated and measured flow rates fluctuated erratically as the thickness of the sediment deposition increased,and the simulated flow water differed from the theoretical one with the difference varying from-0.45%to 8.60%.③When the theoretical flow water was 0.2210 L/s,comparison of the free-surface profiles with and without sediment deposition showed that the simulated and measured profiles occurred at different degrees of water level accumulation near the weir plate;the height of water level increased erratically with the increase in sediment deposition.【Conclusion】Comparison with experimental data showed that the simulation results are accurate and reliable.The water level in front of the weir rises because of the sediment deposition,and the flow capacity of the weir increases as a result.However,as the wire traditional formula does not have a correction term to account for sediment deposition,the flow rate estimated is smaller than the real ones.