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移动式单喷头喷灌机的田间试验表明,如果要保持适宜的喷灌均匀度,随着风速的增大,必须相应地缩小移动的间距。而且当风向与移动方向接近平行时,其移动间距还必须进一步缩小。这里引用一个经验方程来估算移动间距,即在试验喷灌机时,将移动间距作为风速、风向和水压的函数估算之。如果按无风条件下的移动间距进行喷灌,则其水量分布图在有风时是不均匀的。若随之将移动间距变窄以符合大风的条伴,其水量分布图即便在几种风向的条件下,也可能适宜,但是,若风向与移动方向近于平行,则其水量分布图很差。同样,若按有风条件将间距变窄进行喷灌,在风速降低时,其水量分布图也很差。在无风情况下,移动间距为湿润直径的30％至75％,通常获得适宜的均匀度。水量分布不均,使有的地面水量太少,从而降低作物产量;有的地面水量太多,引起深层渗漏,从而导致土壤肥力的损失,能量成本提高,作物产量降低等。均匀喷灌则因土地、喷灌设备、抽水和化肥等费用的增大而显得更为重要。非均匀灌水因深层渗漏而导致水和土壤肥力的损失,使地下水污染,以及某些地面灌水不足和作物减产等。在明尼芬达州中西部,用移动式大流量单咀喷头灌水的耕地面积日益增多,在这个地方喷灌已用于贫瘠而又干旱的地面,播种季节又特别多风。本报告是一篇科研论文,它所叙述的是探讨移动式单喷头喷灌机的性能和大风条件下能提供适宜喷灌均匀度的操作程序。均匀系数(C_u)达0.85以上被认为是适宜的。它可按照克里斯琴逊的公式算出,即:C_u=1-(∑|X_i-|)/(n)………式中:C_u-均匀系数X_i-单个量雨筒在田间测量的灌水深度X_i的平均值n-读数。应用已算出的重叠灌水深度,即可算出不同的移动间距的C_u值。为使各最大移动间距的C_u值达0.85,其最大间距要在每一试验中分别测定之。而且,其最大间距也可根据以前按固定式试验推导出的方程(舒耳等人)(未注明日期)进行计算,並且将它与按移动式喷头数据求得的间距进行了比较,以确定该方程的实用价值,能否作为在不同风速和风向条件下预测移动间距的一般指南。
Field trials of a mobile single-nozzle irrigation machine showed that, to maintain proper sprinkler uniformity, as the wind speed increases, the spacing of the moves must be reduced accordingly. And when the wind direction and the moving direction is nearly parallel, its moving distance must be further reduced. Here, an empirical equation is used to estimate the moving distance, that is, when testing the irrigation machine, the moving distance is estimated as a function of wind speed, wind direction and water pressure. If sprinkler irrigation is carried out at no moving distance under windless conditions, the water profile is not uniform at windy day. If the moving distance is narrowed to conform to the strong wind, the water distribution may be suitable even in several wind directions. However, if the wind direction and the moving direction are nearly parallel, the water amount distribution is poor . Likewise, if the spacing is narrowed for sprinkler irrigation on windy conditions, the water profile is also poor at lower wind speeds. In the absence of wind, the moving distance is 30% to 75% of the wetted diameter, usually with a suitable degree of uniformity. Uneven distribution of water, so that some of the ground water is too small, thereby reducing crop yield; some ground water too much, causing deep leakage, resulting in loss of soil fertility, energy costs, crop yields and so on. Even sprinkler irrigation is more important due to the increased costs of land, sprinkler irrigation, pumping and fertilizer. Heterogeneous irrigation results in loss of water and soil fertility due to deep seepage, pollution of groundwater, inadequate watering on some grounds, and reduced production of crops. In central and western Minnefinda, the area of arable land flooded with mobile high-flow single-jet nozzles is growing, where sprinkler irrigation has been applied to barren and arid ground and the planting season is particularly windy. This report is a research paper that describes the performance of a mobile single-nozzle irrigation machine and the operating procedures that provide optimum sprinkler uniformity under strong winds. A uniform coefficient (C_u) of 0.85 or more is considered to be suitable. It can be calculated according to Christensen’s formula, namely: C_u = 1- (Σ | X_i- |) / (n) ......... Where: C_u-uniform coefficient X_i- single measuring tube in the field of irrigation depth The average value of X_i - the reading. By applying the calculated depth of overlap irrigation, the C_u values of different moving distances can be calculated. In order to make the maximum moving distance of C_u value of 0.85, the maximum spacing to be determined in each test separately. Furthermore, the maximum spacing can also be calculated from the equation (undated) previously derived from stationary tests (unsurprising) and compared to the distance calculated for the mobile nozzle data to Determining the practical value of this equation can be used as a general guideline for predicting the moving distance under different wind speeds and wind conditions.