喻黎明,李俊锋,李娜,等. 不同网孔与筒体模型对Y型网式过滤器性能的影响[J]. 农业工程学报,2023,39(14):97-105. DOI: 10.11975/j.issn.1002-6819.202303141
    引用本文: 喻黎明,李俊锋,李娜,等. 不同网孔与筒体模型对Y型网式过滤器性能的影响[J]. 农业工程学报,2023,39(14):97-105. DOI: 10.11975/j.issn.1002-6819.202303141
    YU Liming, LI Junfeng, LI Na, et al. Effects of different screen mesh and cylinder models on the performance of Y-type screen filter[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2023, 39(14): 97-105. DOI: 10.11975/j.issn.1002-6819.202303141
    Citation: YU Liming, LI Junfeng, LI Na, et al. Effects of different screen mesh and cylinder models on the performance of Y-type screen filter[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2023, 39(14): 97-105. DOI: 10.11975/j.issn.1002-6819.202303141

    不同网孔与筒体模型对Y型网式过滤器性能的影响

    Effects of different screen mesh and cylinder models on the performance of Y-type screen filter

    • 摘要: Y型网式过滤器广泛运用于微灌系统,其良好的水力性能是保证微灌系统稳定运行的关键,为了分析其水力性能,该研究采用数值模拟和物理试验相结合的方法,分析了网式过滤器在3种滤网网孔(正方形、圆形、菱形)以及3种筒体弧线角度(0°、15°、30°)下,过滤器内压降系数、滤芯网面流量分布、内部流场、压力分布等水力特性的变化。结果表明:物理试验与数值模拟之间的水头损失系数平均差异为9%,表明了数值模拟的可靠性,其中圆形网孔过滤器水头损失系数最大,正方形次之,菱形最小;滤网网孔形状对过滤器网面过流量分布的影响较大,正方形网孔过滤器的中速过流量区域占比最高达到了47.5%,圆形次之,菱形最小仅为26.5%。过滤器的水头损失随着筒体弧线角度的增加而逐渐减小,35°的压降系数较0°的减小了73.15%,网面流量的分布也随着角度的增加变得更为均匀,其中35°的中速过流量区域面积较0°增大了71.5%,水力性能明显提高;此外随着筒体弧线角度的增加,出口侧中上段滤网处的内外压差明显减小。因此在实际微灌系统中,选择网孔为正方形、筒体弧线角度30°的过滤器,其内部流场缓和、网面流量分布均匀,提高了过滤器的水力性能和使用寿命。该研究成果可为网式过滤器结构优化提供设计方案与理论依据。

       

      Abstract: Y-type mesh filters have been widely used in the micro-irrigation systems. A better hydraulic performance is highly required for the stable operation during irrigation. In this study, the standard k-model was adopted to simulate the internal flow field of different filters using the computational fluid dynamics with multi-angle analysis. A series of simulation tests were carried out under three types of filter screen shapes (square, circular and diamond) and three angles of cylinder arc (0°, 15°, and 30°). Specifically, a systematic analysis was implemented on the hydraulic characteristics of the internal pressure drop coefficient, the flow distribution on the surface of the filter element, the internal flow field, and the pressure distribution. Physical tests were also conducted to verify the numerical simulation. The results show that: There was 9% average difference in the head loss coefficient between the physical test and the numerical simulation, indicating the better reliability of the numerical simulation. The head loss of the filter was concentrated on the outlet side of the screen, which was accounted for 85% of the total head loss. A stagnant zone of water flow was formed inside the plug, where the velocity was very low without the water flowing back. The smallest pressure was found in the center of the filter chamber from the center to the surrounding area. There was also an increase in the minimal pressure in a stepwise manner from the center to the periphery. Among them, the circular mesh filter shared the largest head loss coefficient, followed by the square mesh filter, and the smallest was found in the diamond mesh filter. The pressure dropped at the mesh, and the total pressure dropped to change, as the shape of the mesh changed. But there was no variation in the value and distribution of the maximum and minimum pressure in the chamber. It infers that the shape of the mesh posed a greater influence on the distribution of the overflow rate on the mesh surface of the filter. The highest proportion of medium-rate overflow area was 47.5% in the square mesh filters, followed by the circular shape, and the smallest medium-rate overflow area of diamond shape was only 26.5%. The head loss of the filter gradually decreased with the increase of the arc angle of the cartridge. The pressure drop coefficient at 35° decreased by 73.15%, compared with 0°. There was also the much more uniform distribution of the flow rate on the mesh surface with the increase of the angle, in which the area of the medium speed overflow area at 35° increased by 71.48%, compared with 0°, indicating the outstandingly improved hydraulic performance. There was the significant decrease in the internal and external pressure difference at the middle and upper section of the screen on the outlet side with the increase of the arc angle of the cartridge , particularly for the differences between 35° and 0°. The difference of the pressure drop between 35° and 0° was 2.97 times. Therefore, an optimal filter can be selected with a square cylinder arc angle of 30°in the actual micro-irrigation system, in order to improve the hydraulic performance and service life of the filter with the gentle internal flow field and uniform flow distribution on the mesh surface.

       

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