微孔混凝土灌水器形状及其尺寸对流量的影响

为揭示微孔混凝土灌水器形状及参数对流量的影响,提高微孔混凝土灌水器选用的合理性,该文以砂子、水泥、硅溶胶为原料,采用干压结合雾化加湿法制备开口孔隙率为20.3%~20.5%的微孔混凝土圆片和圆管试样,然后将2种试样组装成灌水器,研究微孔混凝土灌水器的形状及参数对流量的影响。结果表明:片状灌水器的流量随圆片直径增加而增大,随圆片厚度增加而减小,片状灌水器的单位面积流量只取决于圆片厚度,与圆片直径无关,当水头为3 m时,随着圆片厚度由5 mm增至20 mm,片状灌水器的单位面积流量由40.5 m L/(h·cm~2)降至25.7 m L/(h·cm~2);管状灌水器流量随圆管长度和直径增加逐渐增大,管状灌水器的单位面积流量随圆管厚度增加而减小,随圆管直径增加逐渐增大。该研究为微孔混凝土灌水器的科学应用提供了理论依据。

Influence of shape and size on flow rate of microporous concrete irrigation emitters

Microporous concrete irrigation emitters possess excellent hydraulic performance. The influence of opening porosity on the flow rate of the microporous concrete irrigation emitters has been studied in detail, while the influence of structural shape and parameters on the flow rate of microporous concrete irrigation emitters remains unclear. The water requirement of different crops could be satisfied by adjusting the opening porosity to change the flow rate of the microporous concrete irrigation emitters. In order to make the further improvement of irrigation effect and make rational use of the microporous concrete irrigation emitters, the study in this paper was focused on revealing the influence of shape and parameters on the flow rate of microporous concrete irrigation emitters. We took sands and cement as raw materials and silica solution as adhesive, and prepared 2 kinds of microporous concrete specimens with mean pore size of 2.5-2.6 μm, opening porosity of 20.3%-20.5% and flexural strength of 3.2 MPa by using a combined technique of dry pressing and atomizing humidifying curing, and then 2 types of irrigation emitters were made by assembling the disk and tube specimens respectively in plastic casings. The irrigation emitters were installed on the hydraulic performance test platform, and then the flow rate of the 2 types of irrigation emitters was measured. By changing the water head of the hydraulic performance test platform, the diameter and thickness of the disk, the length, diameter and wall thickness of the tube, the influence of structural shape and parameters on the flow rate of microporous concrete irrigation emitters was studied systematically. For the disk-type irrigation emitters, the flow rate increased with the increase of disk diameter while decreased with the increase of disk thickness, the flow rate per unit area depended completely on the disk thickness but had nothing to do with the disk diameter. When the water head was 3 m, the flow rate per unit area of the disk-type irrigation emitters decreases gradually from 40.5 mL/(h·cm2) to 25.7 mL/(h·cm2) as the disk thickness increased from 5 mm to 20 mm. For the tube-type irrigation emitters, the flow rate increased gradually with the increase of length and diameter of the tube while it decreased gradually with the increase of wall thickness, the flow rate per unit area was great impacted by both diameter and the wall thickness of the tube. Basically, the flow rate per unit area of the tube-type irrigation emitters decreased obviously with the increase of wall thickness but increased gradually with the increase of tube diameter. Though the thickness of disk and tube was the same, the flow rate per unit area of the tube-type irrigation emitters was always lower than that of the disk-type irrigation emitters. As the tube diameter increased, the flow rate per unit area of the tube-type irrigation emitters increased gradually and got closer and closer to the flow rate per unit area of the disk-type irrigation emitters. When the water head was 3 m, as the tube diameter increased from 60 mm to 120 mm, the flow rate per unit area of the tube-type irrigation emitters with wall thickness of 5, 10, 15, 20 mm increased gradually and reached to their respective theoretical value of 40.5, 35.4, 30.6 and 25.7 mL/(h·cm2). The results in this paper provide valuable information for scientific use of microporous concrete irrigation emitters. In the actual process of irrigation, according to the results in this study, selecting and using microporous concrete irrigation emitters with suitable shape and parameters will be conducive to water absorption of crop, and also be helpful to improve water-saving effect of the microporous concrete irrigation emitters.