| Drip irrigation is considered to be one of the best irrigation methods for water saving,and it has been widely used all over the world with its advantages of saving water and energy,increasing production and efficiency.At present,in the application process of drip irrigation system,the clogging of the irrigator has become a bottleneck problem restricting the application of drip irrigation technology,and it is also an international problem.A large number of practical results have proved that regular flushing of the capillary is very effective and necessary to extend the service life of the drip irrigation system.At present,most of the drip irrigation systems at home and abroad use the method of manually opening the tail of the capillary,and then manually closing it after no obvious impurities flow out.For a drip irrigation system with a certain scale,under the cumbersome flushing operation process and huge manpower consumption,most managers only perform capillary flushing once at the beginning or end of the entire crop growth period,which cannot achieve the expected results.The capillary end flushing valve can be automatically opened every time the drip irrigation system starts to run,and after a period of flushing,the valve will automatically be closed.By comparing the structure and hydraulic performance of the elbow-type and in-line flushing valves on the market,the elbow-type flushing valve is determined as the preferred structure for this study,and the design mechanism and structural parameters of the automatic flushing valve at the end of the capillary are selected.And optimization,because of technology confidentiality and patent protection abroad,there is no public information to be found,and related research is rare in China.In this regard,this article carries out experimental research in the following aspects:(1)Through the hydraulic performance test of the flush valve,the hydraulic performance and the response law of influencing factors are explored and analyzed.The flushing time is negatively related to the inlet pressure.The flushing water volume is affected by both the inlet pressure and the flushing time.Increasing the dentation length and dentation width reduces the minimum flow area of the water flow and reduces the flow of water into the upper cavity.Increasing the flushing time and flushing water volume of the flushing valve,increasing the height of the lower cavity can increase the deformation volume,and increasing the height of the valve cover can increase the amount of water entering the upper cavity.The order of the primary and secondary effects on the flushing time and flushing water volume is dentation width>lower Cavity height>dentation length>valve cover height;the flushing flow rate of the flushing valve is less affected by the structural parameters of the flushing valve,and is mainly related to the inlet pressure.(2)This paper introduces the flow channel outlet flow parameters,and builds a mathematical model between hydraulic performance(flushing time and flushing water volume)and influencing factors(inlet pressure,flow channel outlet flow,valve cover height and lower cavity height).At the same time,this chapter introduces the collaborative optimization method based on UG three-dimensional parametric modeling-ANSYS Workbench fluid simulation-OASIS intelligent iterative optimization,with the flow channel outlet flow rate of 0.7mL/s as the target target,intelligent and rapid selection under different inlet pressures The flow channel structure parameters of the flushing valve.Randomly match the selected flow channel structure parameters with the height parameters of the bonnet and the height of the lower cavity and 3D print them into real objects.The hydraulic performance test is carried out under different inlet pressures,and the measured solutions are compared with the hydraulics.The performance mathematical expression regression solution is compared and analyzed to verify the reliability of the mathematical expression and the collaborative optimization method.The results show that the relative error RE of the flushing time and the flushing water volume are both within 15%,which verifies the accuracy of the mathematical expression of the flushing valve hydraulic performance and the reliability of the collaborative optimization method.In the subsequent development and improvement of flushing valves,designers can predict the hydraulic performance of flushing valves based on mathematical expressions.At the same time,they can use reverse thinking to inversely deduce the parameter combinations of influencing factors based on actual engineering requirements for performance parameters such as flushing time.Using the collaborative optimization method,the flow channel parameter combination can be quickly selected to determine the value of each parameter of the flushing valve under a specific flushing time requirement.(3)Numerical simulation study on anti-clogging performance of water-sand two-phase flow of flushing valve,qualitatively exploring the influence of parameters on its own anti-clogging performance.From the numerical analysis of the flow rate inside the flow channel,particle movement time,etc.,with the increase of the flow channel tooth length,the anti-clogging performance of the flushing valve improves,but a larger increase in the flow channel tooth length causes the water flow to form a vortex in the main flow area,which decreases Particle passing rate;as the tooth width of the flow channel increases,the anti-clogging performance decreases;as the inlet pressure increases,the anti-clogging performance increases,but increasing the pressure will increase the probability of particle collisions,which leads to an increase in particle movement distance;According to the analysis of the particle pass rate of the flush valve flow path under the parameter combination,the flush valve flow path has better anti-clogging performance,but its anti-clogging performance needs to be tested in actual engineering.(4)Apply different specifications of flushing valves to the sediment drip irrigation system,and monitor the changes in the hydraulic performance of the flushing valve and the flow rate of the irrigator for a long time to test the anti-clogging performance of the flushing valve and its influence on the anti-clogging performance of the irrigator.The hydraulic performance of the flushing valve is relatively stable,indicating that its own anti-clogging performance is better.The sediment mainly exists in the upper cavity of the flushing valve;in this drip irrigation system,the 30s flushing valve is sufficient to effectively relieve the clogging of the irrigator.After the system runs,The corresponding irrigators Dra and Cu are 98.5%and 99.4%,respectively,indicating that the flush valve can alleviate the problem of irrigator clogging;the dry weight of the clogging substance inside the irrigator and the dry weight of the capillary wall clogging substance have a good correlation. |
PDF Full Text Request