Structure Optimization And Hydraulic Performance Research Of Negtive Pressure Feedback Jet Sprinkler

With the development of water-saving irrigation,the proportion of micro-sprinkler irrigation area will be greatly increased,and the technology of sprinkler irrigation will be widely used and rapidly developed.As the key component of sprinkling irrigation system,sprinklers determine the cost and quality of sprinkling irrigation system.Negative pressure feedback jet sprinkler is a new type of dual-nozzle rotating sprinkler with pulse characteristics,which is designed based on the principle of jet wall attachment switching.It has the advantages of simple structure,low cost,long range and good stability.Based on the previous research,this dissertation further systematically optimized the flow channel of the sprinkler,and optimized the drive plate structure with greater influence on the sprinkler's water distribution.This will further improve the water distribution of the sprinkler,improve the hydraulic performance of the sprinkler and provide theoretical support for the development and application of the jet sprinkler.The main contents of this paper are as follows:(1)According to the existing research,the design intervals of seven flow channel parameters were determined,including the potential difference ratio,sidewall inclination Angle,split pitch ratio,depth to width ratio,curvature radius ratio of elbow,relative length of main and auxiliary nozzle,elevation Angle.Based on the numerical simulation of 162 sets of negative pressure feedback jet sprinkler flow channel model,the design range of main nozzle radius and auxiliary nozzle radius were determined,which were 4.0~4.5 mm and 3.5~4.5 mm,respectively.Orthogonal test was designed in this paper,and the inlet flow and range were taken as evaluation indexes to analyze the hydraulic performance of each structure channel within the design range of the above eight channel structure parameters.The dissertation has determined that the channel structure with small inlet flow and long range was the optimal model,and its specific parameters were the position difference ratio of 0.475,the inclination angle of sidewall of 12.0°,the split distance ratio of 9.0,the depth width ratio of 2.5,the curvature radius ratio of elbow of 3.0,the relative length combination of main and auxiliary nozzles of 8×6,the diameter combination of main and auxiliary nozzles of 4.5 mm×3.5 mm,and the elevation angle of 30°.At the same time,the pulse characteristics of the optimized channel model were further analyzed(2)Processing experimental prototype,creating negative pressure feedback jet sprinkler test rig,within the scope of the inlet pressure of 0.15~0.30 MPa,this dissertation has adopted the control variable method,has changed the Angle,tooth chamfer radius of curvature and teeth groove depth of three key structural parameters in turn,and has carried out 6 kinds of obliquity,5kinds of groove curvature radius,5 kinds of teeth groove depth 16 group of hydraulic performance test driver board structure.The test results showed that under the inlet pressure of0.15~0.30 MPa,the sprinkler range,inlet flow rate and irrigation intensity were independent of the structure of the driving plate,which were 13.0~15.0 m,1.265~1.767 m~3/h,2.384~2.495mm/h in turn.With the increase of the angle of the driving plate,the spray water of the auxiliary sprinkler was concentrated near,the hydraulic performance of the sprinkler was the best when the angle of the driving plate was 16°.With the reduction of the radius of curvature of the driving plate,the water volume of the sprinkler was close to the nearest place.The hydraulic performance of the sprinkler was the best when the radius of curvature of the driving plate was40 mm.With the increase of the cogging depth of the driving plate,the water quantity of the sprinkler was close to the nearest place.The hydraulic performance of the nozzle was the best when the depth of the teeth was 2.5 mm.(3)The hydraulic performance of the negative pressure feedback jet sprinkler before optimization,the negative pressure feedback jet sprinkler after optimization and the hydraulic performance of the rocker arm sprinkler were compared under the same conditions,the test results showed that compared with before optimization jet sprinkler,sprinkler range increased by6.6%~9.5%after optimization,sprinkler irrigation intensity was reduced by 22.3%~28.4%,sprinkler irrigation uniformity coefficient increased by 0.8~4.4%;Compared with the rocker arm sprinkler,the range of sprinkler after optimization was improved by 8.1%~10.4%,the intensity of sprinkler was reduced by 10.3%~16.9%,and the uniformity coefficient of sprinkler head was increased by 4.0~9.3 percentage points.(4)According to the optimized negative pressure feedback jet sprinkler,cubic spline interpolation was used to interpolate radial water flow of nozzle by MATAB software.The distribution of water quantity in typical area was calculated under different combination spacing.Sprinkler irrigation uniformity coefficient was calculated by Christiansen formula.Under the condition of inlet pressure of 0.15,0.20,0.25 and 0.3 MPa,the best combination space of square combination of negative pressure feedback jet sprinkler was 16.5,16.9,17.9 and 18.6 m,respectively.