考虑工作压力的垂直摇臂式喷头可调结构参数优化与试验

为了使垂直摇臂式喷头运行时处于最优水力性能状态,采用中心复合试验设计与响应曲面分析对喷头的可调工作参数进行优化研究。以配重与旋转中心的距离、工作压力和喷嘴直径为变量,以喷灌变异系数、平均喷灌强度、正方形布置均匀系数和正三角形布置均匀系数为响应指标,建立了不同响应指标与变量的多元回归模型,研究了各因素及其交互作用对不同响应指标的影响。利用回归模型进行单目标与多目标的参数优化,并对其进行试验验证。结果表明:各因素对喷灌变异系数的影响顺序依次是:工作压力、喷嘴直径、配重与旋转中心的距离;对平均喷灌强度的影响顺序依次是:喷嘴直径、配重与旋转中心的距离、工作压力;对正方形布置均匀系数的影响顺序依次是:工作压力、配重与旋转中心的距离、喷嘴直径;对正三角形布置均匀系数的影响顺序依次是:工作压力、配重与旋转中心的距离、喷嘴直径。多目标优化下的最佳组合参数为:配重与旋转中心的距离116 mm、工作压力543 k Pa、喷嘴直径12.6 mm,其对应的喷灌变异系数、平均喷灌强度、正方形布置均匀系数和正三角形布置均匀系数分别为:0.27、6.37 mm/h、87.60%、87.93%,预测值与试验值的误差小于5%,预测回归模型具有较高的可信度。该研究可为垂直摇臂式喷头的设计以及合理调节配重与旋转中心的距离、工作压力和喷嘴直径使喷头运行时处于最优水力性能提供参考。

Optimization and experiment of adjustable structural parameters for vertical impact sprinkler with working pressure

Abstract: The adjustable structural parameters of sprinkler were optimized in order to get the optimal hydraulic performance of vertical impact sprinkler. The variation coefficient of sprinkler irrigation, average application rate of sprinkler irrigation, uniformity coefficient under square arrangement and uniformity coefficient under regular triangle arrangement were taken as response indices to analyze the influence of distance between counterweight and rotational center, working pressure and nozzle diameter on hydraulic performance. The experimental study on the adjustable parameters of vertical impact sprinkler with working pressure was performed with the central composite design and the response surface methodology. The multiple regression models between the different response indices and working parameters were established. The analysis of variance was used to analyze the influence of the factors and their interactions on different indices according to the analytical results. The multiple regression models were used to optimize the indices by single-objective optimization and multi-objective optimization. Finally, the effectiveness was validated through an experiment. The results showed that: the significance order of impact factors for variation coefficient of sprinkler irrigation was working pressure, nozzle diameter, and distance between counterweight and rotational center; that for average application rate of sprinkler irrigation was nozzle diameter, distance between counterweight and rotational center, and working pressure; that for uniformity coefficient under square arrangement was working pressure, distance between counterweight and rotational center, and nozzle diameter; that for uniformity coefficient under regular triangle arrangement was working pressure, distance between counterweight and rotational center, and nozzle diameter. R2 value of multiple regression models for variation coefficient of sprinkler irrigation, average application rate of sprinkler irrigation, uniformity coefficient under square arrangement and uniformity coefficient under regular triangle arrangement were 0.9576, 0.9696, 0.9559 and 0.9546 respectively. Under the condition of single-objective optimization, the optimal parameter combination for the minimum variation coefficient of sprinkler irrigation was figured out as follows: the distance between counterweight and rotational center was 126 mm, the working pressure was 600 kPa, and the nozzle diameter was 16.6 mm; the optimal parameter combination for the minimum average application rate of sprinkler irrigation was that the distance between counterweight and rotational center was 115 mm, the working pressure was 219 kPa, and the nozzle diameter was 12.5 mm; the optimal parameter combination for the maximum uniformity coefficient under square arrangement was that the distance between counterweight and rotational center was 143 mm, the working pressure was 585 kPa, and the nozzle diameter was 23.7 mm; the optimal parameter combination for the maximum uniformity coefficient under regular triangle arrangement was that the distance between counterweight and rotational center was 115 mm, the working pressure was 219 kPa, and the nozzle diameter was 12.5 mm. Under the condition of multi-objective optimization, the optimal parameter combination for the minimum variation coefficient of sprinkler irrigation and average application rate of sprinkler irrigation, the maximum uniformity coefficient under square arrangement and uniformity coefficient under regular triangle arrangement was that the distance between counterweight and rotational center was 146 mm, the working pressure was 583 kPa, and the nozzle diameter was 23.4 mm; and its corresponding variation coefficient of sprinkler irrigation, average application rate of sprinkler irrigation, uniformity coefficient under square arrangement and uniformity coefficient under regular triangle arrangement were 0.27, 6.37 mm/h, 87.60% and 87.93%, respectively. The optimization results were validated, and the error between predicted values and experimental values was less than 5%, which indicated the predicting regression models had high credibility. The study provides the reference for designing the vertical impact sprinkler and properly regulating the working parameters to get the optimal hydraulic performance.