导流片对Y型网式过滤器性能的影响

针对网式过滤器内部导流片改变了原有的水沙运动规律,使其水沙运动更加复杂的现状,该文采用CFD-DEM耦合数值模拟和试验测试的方法,对比分析了有无导流片时,过滤器内的水流运行、流量分布及压降系数等水力特性的变化,研究了沙粒在网腔和滤网面上的运动及分布情况。结果表明:与无导流片时相比,导流片使得滤网面上流量变得均匀。清水试验时,有导流片的压降系数较无导流片的大17.92%,水头损失大。过滤浑水时,有导流片的过滤器压降系数小,流速下降比变化平缓,过流能力明显提高;沙粒主要分布在滤网面中心线上及两侧较大流量的位置,有、无导流片时堵头内的沙粒数占总数比分别为90.07%、50.98。导流片的安装减少了泥沙在滤网面上的堆积,提高了过滤器的抗堵塞性能。

Effects of guide vanes on performance of Y-screen filter

The guide vanes can make movement of water and sand in the filter more complicated and difficult to distinguish as it changes the water and sand movement. The characteristics of water movement, the change of flow rate distribution and pressure drop coefficient were analyzed for the filter with or without guide vanes filter. Simulation with CFD-DEM (computational fluid dynamics-discrete element method) and experimental method were used to study the movement and distribution law of sand in the filter cavity and on the screen surface. The results showed that under the condition of clean water, the pressure drop coefficient of the filter with the guide vanes was 17.92% higher than that without the guide vanes, and the head loss was larger than that without the guide vanes also. While filtering the muddy water, the head loss of the guide vanes filter was smaller than that without a guide vanes, and the flow rate decreased more gently than that of clear water. The flow capacity of the filter with the guide vanes was significantly increased, and both the filtration effect and efficiency were improved. The flow field distribution on the screen filter without the guide vanes was extremely uneven, and the difference between the maximum flow rate and the minimum flow rate was 4.9 times. Compared with characteristics of water movement in the filter with and without guide vanes, the maximum flow rate of the guide vanes filter decreased by 4.78% while the minimum flow rate increased by 10.75%, and the area of the high-speed flow area decreased by 47.05% when it was greater than 13 L/h. That indicated that the guide vans had the characteristics of diversion and distribution, making the flow in and out of filter more stable. When the filter was without guide vanes, the sand was mainly distributed on the center line of the screen and on both sides, these positions correspond to areas with high flow rate. The sand was mainly distributed in the plug, which accounted for 90.07% when the filter was with guide vanes at the time of 4 s, and a small amount of sand was on the screen surface, while only 50.98% of the sand was in the plug of filter without guide vanes. It could be seen that the guide vanes let more particles flow to the plug with the water flow, and fewer particles are distributed in the filter chamber and attached to the filter screen, then the probability of blocking was reduced. Through the muddy water experiment, the filtration performance of the filter with and without the guide vanes was tested. The experiment results showed that the filtration volume of the guide vanes filter was larger than that without the guide vanes at the same time, which indicated that the filter with guide vanes had higher filtration efficiency. The distribution of particles of experiment on the filter screen was basically consistent with the distribution of simulation results. Therefore, reasonable design of guide vanes and plug can improve the anti-clogging performance of the screen filter.