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Study On Hydraulic Performance Of Segmentation Bidirectional Flow Drip Irrigation Emitters

Posted on:2020-09-19Degree:MasterType:Thesis
Country:ChinaCandidate:J L LiFull Text:PDF
GTID:2393330596479397Subject:Agricultural Soil and Water Engineering
Abstract/Summary:PDF Full Text Request
Segmented bidirectional flow channel is a new type of drip irrigation emitter.It is of great significance to develop the structure and analyze the mechanism of segmented bidirectional flow channel,to study on hydraulic performance and flow stabilization mechanism of improved bidirectional flow channel under different pressure intervals.In this paper,the combination of experimental analysis and Fluent numerical simulation is used to study the hydraulic performance of different structures.The main conclusions are as follows:(1)Based on Fluent software,the effects of mesh generation and turbulent model selection on the accuracy of numerical simulation are studied.Comparing and analyzing the experimental and simulated values of 3 groups of improved bidirectional flow channels,the mesh size 0.10mm and standard k-? model should be selected.Under this method,the relative errors of the flow rate and the flow index are 0.108%?1.343%and 0.134%?1.730%,respectively.(2)According to L25(56)orthogonal table,25 groups of improved bidirectional flow channel structure parameters calculation scheme is formed.By using the numerical simulation,the minimum flow rate of 25 groups of flow channels is 1.498L/h under 0.1MPa pressure,the flow index is 0.4008-0.4984,and the flow channel with small flow rate and good hydraulic performance is obtained.From range analysis and regression analysis,we can see that the influence of the angle a between the retaining part and the upper side wall on the flow index is the greatest and the influence is significant,and there is a positive correlation.(3)The flow index of different flow channels under different pressure intervals is analyzed,and the results show that 25 groups of improved bidirectional flow channels are in the low pressure region of 0.05?0.15MPa,the flow index is 0.4036?0.5125,and in the high pressure region of 0.15?0.25MPa,the flow index is 0.3075?0.4888.The hydraulic performance of the flow channel in the high pressure region is better than that in the low pressure area,and the difference of the flow index in the high and low pressure regions is great.The mechanism of steady flow in channel shows that the distribution of pressure field is different with different structure of the emitters,but the pressure is decreasing by sections.(4)The calculation results of 9 component segmented bidirectional flow channels show that the flow index is 0.4081?0.4475,and the minimum flow rate at 0.1MPa pressure is 1.663L/h,and less than 2L/h.Better hydraulic performance can be obtained while maintaining the small flow rate of the emitter.The mechanism of steady flow in segmented bidirectional flow channel shows that the greater the pressure drop is,the better the hydraulic performance is.When the flow ratio of negative flow and positive flow is 0.609?0.940,the larger the ratio is,the smaller the flow index is.
Keywords/Search Tags:Segmented bidirectional flow channel, Drip irrigation emitter, Structural parameters, Hydraulic performance, Numerical simulation
PDF Full Text Request
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