Research On Flow Resistance In Labyrinth Emitter

Study on flow resistance in labyrinth emitter is part of the hydraulicperformance, mainly affected by its flow characteristics and structural parameters. Inthis paper, self-designed channel and labyrinth channel were studied by means of thePIV and CFD simulation. The paper has done a research on flow characters inlabyrinth channel, confirmed the relationship between the inner head loss andvelocity. Furthermore, the CFD simulation was confirmed and by the means of thistool, the effect due to the structural changes on the flow resistance was probed.According to the research, several conclusions were obtained as followings:1. The emitter size of the flow channel is between micro channel and macrochannel, For the straight channel, flow regime transition Reynolds number isbetween1700and2300which means it still comply to the macro hydraulics theory;For labyrinth channel, tracer particles were observed and its internal watermovement were analyzed, but they could not judge the water flow regime.2. For the straight channel, maze section, the frictional head loss has a linerrelationship with the average velocity. For the labyrinth channel, the local head losshas a index relationship with the average velocity, the index is between1.67and3.1,compared with the maze hydraulics turbulence which is between1.75and2, thedifference is obvious. The local head loss accounted for more than90%of the totalhead loss.3. CFD is a powerful tool for solving fluid flow problems, the turbulence modelwas used in the fourth chapter to simulate the flow channel and were compared withexperimental, and the results turned out that the program can be used as a viablesolution. Maze runner internal flow field can be divided into mainstream areas,low-speed areas and whirlpool area; low-speed zone could easily lead to clogging.4. The range analysis shows that the angle α affects the flow coefficient most, followed by the J, the h is the least. When h is1mm, α is65°, J=0, the hydraulicperformance is the best. ANOVA analysis is consistent with the range analysis andaccording to the regression analysis equation x and k between the three parameters。5. The pressure loss on the length of the entire labyrinth channel meets linearreducing law, the α and J affects the head loss coefficient most.