Design Method Of Drippers With Labyrinth Runner Structure In Tooth Shape

Drops the head is the core component of drip irrigation system in our country drops head backward level under the background of independent research and development design,this article mainly has carried on the appropriate tooth shape labyrinth runner structure model selection of the head,relationship between each parameter and the performance of the hydraulic head,tooth shape design of labyrinth runner structure drops head three parts research,this paper proposes a accord with large,medium and small three drops of traffic design scheme.First of all,using computational fluid dynamics CFD software,the tooth profile of three different structure labyrinth runner drops head for numerical simulation of the specific needs of various turbulence model provided by Fluent software,grid type and size,control accuracy are compared,and selection and the simulation value compared with the measured worth deviation size,select the most close to the measured values of the model solution.At the same time,the feasibility of the above numerical simulation scheme in the dropper simulation is further verified in the hydraulic performance test.According to the test results of the hydraulic performance of the dropper,the influences of single factor structural parameters and combined structural parameters on the hydraulic performance of the dropper are explored,and the flow rate,flow coefficient and flow pattern index are analyzed respectively,and the corresponding multiple linear regression equation is established.Finally,according to the significance analysis results of the second part and the linear equation,the reasonable flow of the dropper design is established.The main conclusions are as follows:(1)Fluent software in different turbulence model is suitable for different fluid research conditions.In order to simulate the structure of the tooth shape labyrinth runner outlet flow,flow coefficient,flow index more accurately,three aspects of the hydraulic performance parameters about drippers in different turbulence model,different grid tumble type and size,control accuracy under the simulating test,the results compared with the measured test,from the Angle of the parameters of the deviation value to choose the most close to the real value of the simulation model.The results show that the standard k-? and RNG-?model combined with automatic meshing and hexahedral-dominated meshing method are suitable for the simulation of labyrinth runner structures.The model is adopted to calculate the reliability of the structure,and no further test verification is needed.At the same time,the size of the grid is selected as 0.2mm,the number of grids is controlled between tens of thousands and hundreds of thousands,the residual error control precision of the simulated calculation is 0.001,in this case,the convergence rate is 100%,and the number of calculation steps for more than 90% structures to reach the convergence is within 5000 steps.(2)According to the analysis of the structural parameters and the hydraulic performance of the drippers,the flow rate of the drippers decreases with the increasement of the number of flow units,and the flow rate of the drippers is negatively correlated with the number of flow units.There was no significant positive or negative correlation between the flow rate and the pitch on the whole.Drops of flow and flow of head tooth Angle between a 120 ° Angle of turning tear,overall,drops were positively correlated relationship between flow and tooth Angle of head.Under the conditions of different tooth spacing,number of runner units,width of runner and depth of runner,the relationship between the flow coefficient of the tip and the tooth Angle of the tip presented a positive correlation on the whole except for a few cases.(3)According to the test results of the hydraulic performance of the drippers,the influences of single factor structural parameters and combined structural parameters on the hydraulic performance of the drop head were comprehensively explored,and the significance analysis was carried out from three aspects of flow rate,flow coefficient and flow state index,and the corresponding multiple linear regression equation was established.Significant,according to the results of the analysis of the single factor,drop flow and tooth Angle of head,flow channel width Combination of factors,drop head flow and flow cross sectional area,the total length of flow channel,groove curvature are significant sex,drop head flow coefficient and flow cross sectional area,the total length of flow channel,groove curvature are significant sex,(4)Based on the analysis results of single factor and combination factor structural parameters of the dropper on its hydraulic performance and the linear equation,the reasonable flow chart of the dropper design is established,and the design scheme of the dropper with rated flow rate and flow pattern index is put forward.In the case of tooth rotation Angle of 120°,the initial structure is determined by calculating runner width and runner spacing through linear equations.In the next step,the runner width,runner spacing and runner element number are successively adjusted to obtain the dropper meeting the designed flow rate.The dropper flow rate deviation is controlled within 5% and the flow pattern index is around 0.5.