Modeling and Application of Rotary Refractive Sprinkler Head Mobile Spray Water Distribution Calculation Model

Abstract

【Objective】 Uniformity coefficient is an important parameter in design and operation of sprinkler irrigation. Based on CU and DU, this paper proposed a methods to evaluate whole and local water distribution to help improve design of sprinkler systems and the rational configuration of operating parameters. 【Method】 We propose a uniformity coefficient DUl and DUh based on by defying positive and negative skewed distribution. Water distribution of the Nelson D3000 nozzle was measured and calculated, and the ability of DUl, DUh, CU and DU for evaluating water distribution, sensitivity to deficient or excessive irrigation, and uniformity under different nozzle-spacing and working pressure were compared and evaluated. 【Result】 When the irrigation occurs at 1.5R combined spacing, only DUh shows poor uniformity, where the positive deviation is concentrated in a small region. The sensitivity of CU and DUh was 11.15% and 9.32%, respectively. DUl and DUh were more sensitive to small area deficit irrigation, with sensitivity being 4.69% and 5.70%, respectively. The combined distance has significant influence on DUl, DUh, CU and DU. With the increase in working pressure, DUl and DUh showed significant differences, and the differences were more significant than CU and DU, with the F value being 0.123 and 0.399. DUl, DUh are more accurate. Based on CU level classification standard, the division standard of horizontal classification evaluation index with the dynamic change of uniformity coefficient DUl and DUh with positive and negative deviation distribution is constructed. Assuming an equal distribution of positive and negative deviations, the pass criteria for DUl and DUh are 70% and 130%, respectively. 【Conclusion】 DUl and DUh based on deviation distribution are superior to CU and DU for accurately evaluating water distribution uniformity and optimizing sprinkler configuration.

Keywords

• sprinkler irrigation
• uniformity coefficient
• deviation distribution
• uniformity of distribution
• sensitivity analysis
• significance test