| This research is one of the main contents of National Spark Program “Demonstration and Application of Micro-irrigation of Water-Fertilizer-Pesticide Integrated Technology in Orchard in Hilly and Mountain Area”(No.2015GA690006).The water-pesticide integral micro-sprinkler can irrigate the root of the crops under low pressure,and spray pesticide on the back side of the leaves of crop under medium pressure.In this paper,the water-pesticide integral micro-sprinkler was optimally designed by orthogonal test,numerical simulation and PIV technology,and found the influence of the key structural parameters on hydraulic performance.The main research contents and results were as follows:(1)To optimum design of the key structure of water-pesticide integral microsprinkler on orchard irrigation system.The structure and working principle of waterpesticide integral micro-sprinkler were analyzed.The influence of the diameter of sprinkler outlet,the number of small round hole,the diameter of small round hole,the number of oblique slot and the width of oblique slot on hydraulic performance was studied by orthogonal test.And the optimal structural parameters were determined.The results indicate that: under the conditions of low pressure and medium pressure,the primary and secondary order of geometrical parameters which affect the comprehensive evaluation index is achieved,which is the diameter of sprinkler outlet,the diameter of small round hole,the number of oblique slot,the width of oblique slot,the number of small round hole.The optimal structural parameters is got,which the diameter of sprinkler outlet is 3mm,the number of small round hole is 3,the diameter of small round hole is 2mm,the number of oblique slot is 3 and the width of oblique slot is 0.8mm.(2)To master the influence and change rule of internal flow field through changing the key structural parameters of sprinkler.Numerical simulation was applied to analyze the influence and change rule of the number of small round hole,the diameter of small round hole,the number of oblique slot and the width of oblique slot on the internal flow field of sprinklers.The results indicate that: under low pressure of 150 kPa,the wetted radius is larger when the number of small round hole is 3.when the diameter of small round hole is 2mm,the spraying net height is lower under low pressure of 150 kPa,and the spraying net height and the wetted radius are larger under medium pressure of 350 kPa,which meet the research expectation.When the number of oblique slot is 3 and the width of oblique slot is 0.8mm,the spraying net height is lower and wetted radius is larger under low pressure of 150 kPa,which meet the research expectation under low pressure.(3)To comparatively study velocity and the ending average raindrop diameter of the external flow field between optimized and original sprinklers.The PIV measurement technology was applied to compare the external flow field between optimized and original sprinklers.The results indicate that: with the increase of working pressure,the maximum velocity of the external flow field increase gradually.Under the same working pressure,the maximum velocity of optimized sprinkler is 1.14~1.92 times of that before optimization in external flow field,indicating that the energy conversion efficiency of optimal sprinkler is higher.Under the same pressure,the ending average raindrop diameter of sprinkler with optimal structural parameter is smaller than that before optimization,and the raindrop is more broken and the degree of atomization is more obvious.(4)To comparatively study and comprehensive evaluate hydraulic performance between optimized and original sprinklers.The hydraulic performance of optimal sprinkler was measured,and comparing it with that before optimization.The results indicate that: under the conditions of low and medium pressure,the flow rate of the optimized sprinkler is lower than that before optimization.The slope of curve of sprinkler net height for optimal sprinkler is a stable value compared with that before optimization.And compared with sprinkler before optimization,the ultimate wetted radius and uniformity coefficient of optimized sprinkler are greatly improved,which the ultimate wetted radius is increased by 23.5% and the uniformity coefficient is increased by 16.15%.The hydraulic performance of sprinkler with optimal structural parameters is better than sprinkler before optimization,which meet the research expectation.Based on efficacy coefficient method,optimized sprinkler and sprinkler before optimization were evaluated comprehensively.The results indicated that: the spraying performance of sprinkler with optimal structural parameters is better than sprinkler before optimization. |
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