Study On The Hydraulic Performance Of Two-way Flow Column

The bidirectional flow structure and the columnar emitter are combined to form the bidirectional flow columnar emitter.This paper mainly studies the hydraulic performance of the opposed bidirectional flow column drip irrigation emitter and the splayed bidirectional flow column drip irrigation emitter so that this new type of column emitter can be applied in engineering practice.In this paper,the hydraulic performance of different structures is simulated and analyzed according to the orthogonal design scheme by using the method of combining experiment and numerical simulation.The main conclusions are as follows:(1)Pre-experiment and simulation analysis of three groups of opposed bidirectional flow column drip irrigation emitters show that the flow regime index is 0.441?0.453;In the numerical simulation,the grid size is 0.1mm,and the error between the turbulence model and the test value is the smallest when the turbulence model is the standard model,in which the flow rate and flow state index error are 0.15%?2.45%and 0.20%?0.45%respectively.The design scheme of the opposed bidirectional flow column drip irrigation emitter is L25(56).and the simulation results show that the flow rate reaches 3L/h and the flow index is 0.430?0.459 under the common pressure of 0.1 MPa.(2)The distance g between the water diversion structure unit and the water blocking structure unit has the greatest influence on the flow state index,and the distance r between the water blocking structure unit and the emitter side wall has the smallest intluence on the dlow state index.the distance r between the water diversion structure unit and the water blocking structure unit>the distance e between the water diversion structure unit and the emitter side wall>the height h of the water blocking structure unit>the distance f between the water diversion structure unit and the water blocking structure unit>the distance r between the water blocking structure unit and the emitter side wall.Opposite bidirectional flow columnar drip irrigation emtter is suitable for low pressure interval;Using steady flow index instead of flow index to evaluate hydraulic performance of two-way flow column emitters,19 emitters with better hydraulic performance and 10 emitters with worse hydraulic performance were obtained.(3)Numerical simulation of splayed bidirectional flow column drip irrigation emitter is carried out.The flow regime index ranges from 0.405 to 0.497,and the flow rate ranges from 1.511 L/h to 4.431 L/h at a pressure of 0.1 MPa.The influence order of the splayed structure on the flow state incfex is splayed opening angle ?>the distance j between the two outer sides of the v-shaped water blocking structure unit and the inner side of the water blocking wall is selected>splayed water hole distance 1>the distance k between the two outer sides of the splayed water dividing structure unit and the inner side of the water blocking wall>the v-shaped opening angle ?>the distance m between the apex of the v-shaped water blocking structure unit and the apex of the splayed water dividing structure unit;The two outer sides of the V-shaped water-blocking structure unit are negatively correlated with the distance J inside the water-blocking wall and the flow regime index of the V-shaped opening angle ?.The eight-shaped opening angle ?,the distance K between the two outer sides of the eight-shaped water-dividing structure unit and the inner side of the water-blocking wall,the distance L of the eight-shaped water-passing hole,the flow regime index of the distance M between the apex of the V-shaped water-blocking structure unit and the apex of the eight-shaped water-dividing structure unit are positively correlated.The splayed bidirectional flow column emitter is suitable for high pressure range.