高含沙水渠道测控一体化板闸测流试验及其数值模拟

Flow gauging test and numerical simulation of integrated gate for measurement and control of high sediment content water channel

为了了解测控一体化板闸在高含沙水渠道的测流精度是否满足规范要求,选取宁夏南山台扬水灌区18条测流条件较好且具有代表性的支渠,通过对比无喉道量水槽的测流结果,整理分析不同灌水时期测控一体化板闸的测流数据,采用ANSYS Fluent建立物理模型,模拟研究测控一体化板闸的水力性能随含沙量的变化规律,并结合Rubicon测控一体化板闸测流原理,分析含沙量影响测控一体化板闸测流精度的成因.结果表明:当渠道水含沙量较大时,测控一体化板闸与无喉道量水槽的测流结果偏差较大;板闸计量箱内的流速分布、湍动能、含沙量、沙粒粒径均可能影响超声波流量计的测流精度;随着含沙量的增加,测控一体化板闸计量箱内湍动能减小,但流速分布无明显变化.因此,含沙量对测控一体化板闸测流精度有一定影响,主要由超声波在含沙水中的衰减作用以及含沙水的制紊作用导致,而流速分布对其影响较小.

In order to know whether the flow measurement accuracy of the integrated monitoring and control slab gate in the channel with high sediment concentration meets the specification requirements.18 representative branch canals with good flow measurement conditions in Nanshantai pumping irrigation area of Ningxia were selected.Compared the flow measurement results of the flume without throats,the flow measurement data of the integrated plate gate with measurement and control in diffe-rent irrigation periods were sorted out and analyzed.ANSYS Fluent was used to establish a physical model to simulate and study the variation law of hydraulic performance of the integrated monitoring and control slab gate with sediment concentration.Combined with Rubicon measurement and control integrated plate gate current measurement principle,the causes of sediment concentration affecting the flow measurement accuracy of the integrated plate gate were analyzed.The results show that the deviation of flow gauging between the integrated gates and the cut-throat flume is enlarge when the sediment content of channel water gradually increases.All the elements of the velocity distribution,turbulent kinetic energy,sediment concentration and particle size have effect on the accuracy of ultrasonic flow meter in the measuring box.With the increase of sediment concentration,the turbulent kinetic energy decreases but the velocity distribution has no obvious change in the metering box.Therefore,the sediment concentration has a certain impact on the flow measurement accuracy of the integrated plate gate.Further,it is mainly caused by the attenuation of ultrasonic wave and the turbulent kinetic energy decreases of sediment laden water,and the relative to the velocity distribution has little influence on it.