双向步进式全射流喷头工作稳定性

分析了PXSB50型双向步进式全射流喷头正反向步进过程的差异,从而对其稳定性进行研究.分别研究了喷头射流元件在正反向步进过程中控制导管回路内气液两相流的流动情况,并对回路压差进行了对比.信号导管长度、补气孔的大小及位置影响了喷头的运转步进频率、步进角度和喷头射程.正反向步进频率均随着导管长度的减小而增大,射程随着步进频率的增大而变小.对于相同的导管长度,正向步进频率明显大于反向步进频率,正向射程小于反向射程.补气孔位置离换向结构越近,频率越大,步进角度及射程也随之减小.通过分析和试验,找到了使PXSB50型喷头按照灌溉要求的正向频率及反向频率稳定运行时的喷头导管长度、补气孔大小及位置：取信号水管长度为378 mm,正向导管为648 mm,反向导管为648 mm,正向补气孔直径为2.0 mm,反向补气孔直径为2.5 mm,正向补气孔的位置为3 mm.

Working stability of two-way stepping fluidic sprinkler

The differences between the forward- and backward-stepping process of the two-way stepping fluidic sprinkler of type PXSB50 were analyzed to study the stability of the sprinkler. The gas-liquid two-phase flow in the pipes for controlling forward- and backward-stepping process was studied and the pressure difference in the pipes was compared. The length of the deriving fluid tube, the size and position of the air compensating hole have influence on forward or backward-stepping frequency and angle, spraying range. The frequency was increased but the spraying range was with reducing length. For the same length, the forward-stepping frequency was considerably higher than the backward-stepping frequency; accordingly the spraying range in the forward-stepping process was smaller than that in the backward-stepping process. The closer the air compensating hole was placed to the reversing mecha- nism, the faster the stepping frequency becomes, and the smaller both the stepping angle and the spra- ying range get. For the two-way stepping fluidic sprinkler of type PXSB50, an optimum combination of the length of the deriving fluid tube, the size and position of the air compensating hole was obtained by theoretical analysis and experiment, those parameters as follows： the length of the deriving fluid tube 378 mm, the length of the forward-stepping pipe 648 mm, the length of the backward-stepping pipe 648 ram, the diameter of the forward-stepping air compensating hole is 2.0 mm, the diameter of the backward-stepping air compensating hole is 2.5 mm, the position of the forward-stepping air compen- sating hole is 3 mm.