一、前言时针式喷灌机输水支管上装有若干喷头,其喷头布置一般分为等距和非等距两种布置,喷头出流量均以面积比为依据,因此,输水支管均属多孔非均匀出流.对于这种多孔非均匀出流管道的水头损失计算,美国瞿树东1972年导出了在无末端出流情况下多口系数极限值,见表1,使时针式喷灌机输水支管水头损失计算工作大为简化.但对于有支管末端出流(如装 I. INTRODUCTION There are several sprinklers on the water jet branch pipe of the hour-light sprinkler. The sprinklers are generally divided into two kinds of layouts: equidistant and non-equidistant. The output of the sprinklers are all based on area ratio. Therefore, Uniform outflow for this porous non-uniform outflow pipe head loss calculation, the United States Qu Shu-Dong in 1972 exported without extremes in the case of multi-port coefficient limits, see Table 1, so that the hourglass water pipe branch head Loss calculation is greatly simplified, but for branch ends outflow (such as equipment