| The jet pulse sprinkler is a new type of agricultural water-saving irrigation sprinkler independently developed by Jiangsu University.It has the advantages of long range,high spray uniformity and simple structure.The structure of the runner and the drive plate is the key to the hydraulic performance of the jet pulse sprinkler,but there is currently no overall optimization of the runner structure and the design and research of the drive structure based on the spray characteristics.This thesis adopted the method of combining theoretical analysis,numerical simulation,hydraulic performance test and verification.The relationship between the key structural parameters and hydraulic performance of jet pulse sprinkler and the design method of nozzle flow channel structure were determined.The internal flow characteristics and jet breaking characteristics of the jet pulse sprinkler were revealed.Two new drive plate structures were proposed for the first time,and a jet pulse sprinkler with a new structure was obtained.The specific research contents are as follows:(1)The design method of the flow channel structure of the jet pulse sprinkler was proposed.An eight-factor four-level full-combination test was carried out,and the test found that the design interval of the control runner width was 2mm～5mm,and the design interval of the elbow curvature radius was 24mm～64mm.In determining the design interval,a nine-factor four-level orthogonal test was carried out,and the comprehensive scoring method and the range analysis method were used to reveal the law and degree of influence of each factor level on the performance of the nozzle.The order of the degree of influence was:nozzle diameter,position difference,side wall inclination,split distance,nozzle length,elbow curvature radius,jet element inlet section length,and control flow channel width.The flow channel structure parameters for the best performance of the jet pulse sprinkler were:the diameter of the main nozzle and the auxiliary nozzle was 4.5mm×3.5mm,the position difference was 2.1mm,the side wall inclination was 12°,the split distance was 30mm,and the length of the main and auxiliary nozzles was 56mm×56mm,the radius of curvature of the elbow was 48mm,the length of the inlet section of the jet element was 8mm,and the width of the control flow channel was 5mm.(2)Numerical simulation and high-speed photography experiment of the internal flow of jet pulse sprinkler.The internal flow simulation and test results intuitively revealed the internal flow and jet breaking process of the pulse jet sprinkler,and reveal the reason for the formation of the"water peak"in the distance of the sprinkler from the perspective of jet breaking.It provided a useful reference for the subsequent exploration of the influence of sprinkler internal flow and jet breaking on the hydraulic performance of the sprinkler.The positions of the vortex bubbles and the measured jet pulse frequency in the experiment were consistent with the results of the numerical simulation,which verified the reliability of the numerical simulation method.(3)Two drive plate structures,"claw type"and"groove type"were proposed for the first time.Orthogonal experiments were carried out respectively,and the results showed that the influence degree of each structural factor of the"claw-type"drive plate on the uniformity of the jet pulse sprinkler wass as follows:the bottom width of the triangular drive plate,the length of the drive plate,the inclination of the drive plate,and the width of the drive plate;The structure was:the bottom width of the triangular drive plate was 7mm,the length of the drive plate was 18mm,the inclination angle of the drive plate was 14°,and the width of the drive plate was 11mm.The order of the influence of the structural factors of the"groove"drive plate on the uniformity of the jet pulse sprinkler was:the inclination angle of the inner groove,the length of the drive plate,the width of the groove,the inclination angle of the side drive plate,and the width of the drive plate;the optimal structure was:the inclination angle of the inner groove 13°,the length of the drive plate was 16mm,the groove width was 3mm,the inclination angle of the side drive plate was 17°,and the width of the drive plate was 11mm.(4)The hydraulic performance comparison test of the new-type drive plate jet pulse sprinkler(referred to as the new sprinkler)and the original jet pulse sprinkler and impact driven sprinkler.The test results showed that the range of the new sprinkler was 0.5m longer than that of the original sprinkler,and 1.0m～1.5m longer than the impact driven sprinkler.The flow rate of the new sprinkler was 0.12m~3/h～0.17m~3/h less than the original sprinkler,and 0.07m~3/h～0.16m~3/h than the impact driven sprinkler flow rate.The spraying uniformity of the new"claw type"sprinkler is-0.76%～6.11%higher than that of the original sprinkler,which was 3.75%～12.15%higher than that of the impact driven sprinkler;The uniformity was 7.84%～14.42%higher than that of the impact driven sprinkler.Comprehensive analysis showed that the structure of the"groove type"drive plate was reasonably designed,which significantly improved the hydraulic performance of the sprinkler. |
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