喷头导流器位置参数的计算及其对喷头性能影响

为了准确调节喷头导流器的位置,分析了垂直摇臂式喷头叶片式导流器在水射流中的运动过程,计算了导流器与摇臂转动轴间的距离、导流器中心线偏移射流中心的角度、导流器直叶片与射流中心线的夹角等3个参数各自的关系式。采用二次回归正交组合试验研究了导流器的位置参数对喷头的摇臂频率、步进角度和喷灌均匀度的影响规律。结果表明:影响摇臂频率的主次顺序依次为导流器偏移射流中心的角度、导流器直叶片与射流中心线的夹角和导流器与摇臂转轴之间的距离;影响步进角度主次顺序依次为导流器偏移射流中心的角度、导流器与摇臂转轴之间的距离和导流器直叶片与射流中心线的夹角。摇臂频率随着导流器与摇臂转轴之间的距离增大而减小,导流器偏移射流中心的角度和导流器直叶片与射流中心线夹角增大而增大;喷头的步进角度随着三者的增大而减小。优化之后导流器的位置参数分别为:导流器与摇臂转轴之间的距离为273 mm、导流器偏移射流中心的角度为4°、导流器直叶片与射流中心线的夹角为13°。导流器位置参数优化之后,喷头的水量分布更加合理;且随着组合间距的增加,优化之后的喷灌均匀度要大大高于优化之前。该研究可为垂直摇臂式喷头的设计及优化布置提供参考。

Calculation of sprinkler drive vane positional parameters and its influence on sprinkler performance

Abstract: As the water shortage is becoming more and more serious, water-saving irrigation has become an important part of agriculture modernization. Raising the level of agricultural mechanization and improving the utility ratio of water are necessary ways to access agriculture modernization. As the most important parts in sprinkler irrigation system, sprinklers can spray water into the air, turning into small water droplets and then landing on those crops that need irrigation, their performances directly affect the sprinkler irrigation system and engineering quality. At present, the most representative and most widely used sprinkler of the high pressure sprinklers is vertical impact drive sprinkler. The content of this article contains the following aspects. The motion process of sprinkler drive vane for a vertical impact sprinkler in the water jet was analyzed. In order to accurately adjust the position of the drive vane, the respective regression equations of three parameters were calculated, which are the distance between the drive vane and rocker arm shaft (Factor A), the angle between the centerline of drive vane and that of the jet (Factor B), and the angle between straight vane and the centerline of jet (Factor C). Using quadratic regression orthogonal test, the influences of positional factors of drive vane on the shifting frequency, the angle of step-by-step operation and the Christiansen coefficient of irrigation uniformity were investigated. The impact factors in order for the shifting frequency of drive vane are Factor B, Factor C and Factor A; The angle of step-by-step operation is most affected by Factor B, then by Factor A, last by Factor C; In comparison, the influence of three factors on the Christiansen coefficient of irrigation uniformity is not significant. More exactly, the shifting frequency of drive vane diminishes as the distance between the drive vane and rocker arm shaft increases and it rises with the other two factors. However, the angle of step-by-step operation decreases with the increases of these three parameters. The regression equations were derived by Excel through the optimal combination of factors for the highest irrigation uniformity that figured out: Factor A is supposed to be 273 mm, Factor B is 4° and Factor C is 13°. After the optimization of positional parameters for the drive vane, the water in the near range of sprinkler is supplemented better by the jet compared to that before optimization, thus the water distribution is more reasonable. Further, the Christiansen coefficient of irrigation uniformity under larger sprinkler spacing after optimization is far higher than that before optimization. Therefore, the sprinkler with drive vane in optimized positional parameters is more suitable for the overlapping irrigation. The results can provide a basis for designing and optimal layout of vertical impact sprinklers.