圆形喷灌机非旋转喷头流量系数的研究

分析推导了圆形喷灌机非旋转喷头圆锥形喷嘴流量系数的影响因素和理论公式,并分别对国外D3000喷头和国产PZ喷头的流量系数进行了测试。结果表明:D3000和PZ喷头流量系数的理论计算平均值为0.9377,D3000喷头流量系数测试平均值为0.969,因PZ喷头加工制造精度差,其流量系数测试平均值为0.9121。喷头流量系数的测试平均值高于理论计算平均值3.3%。当圆锥形喷嘴锥角为10.01°～23.18°时,流量系数的合理范围为0.93～0.98,取建议值0.95时,喷头流量的理论计算值与测试值的相对误差均值小于2%,完全可以满足圆形喷灌机喷头配置精度的要求。

Study on the Discharge Coefficient of Nonrotatable Sprays for Center-pivot System

The effect factors and theoretical formulas for discharge coefficient of conical nozzle of nonrotatable sprays used in center-pivot systems were discussed in this paper. And discharge coefficients of the D3000 and PZ sprays were tested respectively. The results showed that the theoretical calculatedmean discharge coefficient for the two sprays is 0.9377 and the measured mean discharge coefficient for the D3000 is 0.969. As the PZ spray has worse machining, the measured value is only 0.9121. With the inside contraction angle ranging from 10.01°~23.18°, the discharge coefficient is 0.93~0.98. When the recommended discharge coefficient is (0.95), the mean relative errors between the calculated and measured discharge of nonrotatable sprays is less than 2%, which can meet the requirement of spray selection.