| China is one of the thirteen water-scarce countries.At present,the growth ofChina’s population and the development of economic have been restricted.Thephenomenon of the rate of the water resources utilization is low,which exitsespecially in agricultural.In order to change this situation,the twelfth five yearplan has focused the Increases of the area of water-saving and improve thetechnology development of the water-saving irrigation.Drip irrigation is themost effective water-saving irrigation technology.It has the advantage of highrate of water use and good irrigation uniformity.The drip irrigation emitter is thecore part of the drip irrigation system and the main part of energydissipation.Because of the size of the emitter,it is easy to be blocked,whichinfluences the irrigation uniformity of the drip irrigation system and scraps thedrip irrigation system.Jam mainly starts from the vortex field.There is fewresearch in vortex field in labyrinth channel.This paper use the rectangle labyrinth emitter as the research object,whichis simulated by FLUENT and gets the diagram of velocity vector,velocitycontours,pressure distribution and the distribution of tangential velocity.ThroughTECPLOT can this paper get the area of the vortex field,the position of thecenter point,the velocity distribution of the vortex field and main flow area,thestrength of the vortex.This paper also analyze flow and rate of flow,whichinfluence the vortex,and get the following conclusions:1) Flow in rectangle labyrinth emitter can be divided into the main flow with high velocity,wortex located in the side wall and small vortex located in thecorner of the channel.With the increase of the flow,velocity in each area getshigher and the streamline gets concentrated.The number of small flow vortexarea decreased gradually with the increase of the flow rate.The small vortex inthe upstream face is larger than it in downstream face.2) With the development of the flow,the area of flow is larger than othersand the area stand still.The center of the vortex do not move,which located inzero speed zone.It means that the development of the flow has no influence inzero speed zone;The change of flow have no influence in the pattern of flow.Thearea of vortex gets bigger with the increase of flow and the center of the vortexmove to downstream.The increase of flow can not change the phenomenon ofthe zero speed zone and can not eliminate the jam generation.3) With the development of flow,the pressure in the area of vortex isdecreased,the change of pressure difference stands the same.The pressurebetween the boundary and the center is larger than it between wall and thecenter.The speed of pressure reduce from the boundary to the center and getlowest in the center.With the increace of flow,the pressure get higher,whichmeans the increase of the flow can improve the effect of energy dissipation andthe increase of flow can improve this function.4) The sediment particles in the import and export in rectangular labyrinthemitter clog easier than them in the middle in rectangular labyrinth.When thespeed of sediment particles get the same velocity in the boundary and they canget in the vortex. The strength of the vortex is largher than it in othervortexes.When the stress can not push the sediment particles out,the vortexmotion can not stop and may get in the zero speed zone.It can cause the channeljam.The other sediment particles also get in vortex when the speed is the sameas the boundary.5) The vortex motion enhances most obviously when the flow increasesfrom5L/h to7L/h.We should maintain the flow at7L/h. 6) The first vortexunder the maximum flow should be used in optimizationof the area of vortex in channel. |
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