Font Size: a A A

The Comparison Of Flow Field And Pressure Field In Different Types Of Labyrinth Emitter

Posted on:2015-04-14Degree:MasterType:Thesis
Country:ChinaCandidate:S YangFull Text:PDF
GTID:2283330434459066Subject:Hydraulic engineering
Abstract/Summary:PDF Full Text Request
Water is a very precious natural resource, and the survival and development of human society is inseparable from it. China is one of the thirteen severe water shortages countries, which has water resources is very scarce. With the rapid development of economy and population in our country, The demand of water resources is increasing, which also contributed to the strain on water resources, but also aggravate the shortage of water resources situation.Therefore, our government and related departments advocate to save water, and they aslo great promote water conservation measures.Our country is a large agricultural country, which use huge years of irrigation water. But traditional irrigation technology has been used in most regions of our country, which cause the waste of water resources seriously. Now, Some countries in the world began to promote and apply the water-saving irrigation technology.Because it can rational use water resourcesand promote the advantages of crop production.The drip irrigation is a more advanced water-saving irrigation technology is more advanced,which compared with Pipe Irrigation and,sprinkler irrigation techniques has the highest water utilization.Drip Irrigation Emitter is considered to be the best equipment of water-saving irrigation technology. It has the characteristics of high rate, strong environmental adaptability with water. Labyrinth channel is the best channel structure of Irrigation Emitter,which is complex that make its energy dissipation capability high. The excellent hydraulic performance emitter,which has high anti clogging performance and irrigation uniformity. So the study on the hydraulic performance of emitters is very important. Channel structure is the key factor that affects the hydraulic performance of emitters. In recent years, a lot of research that about the influence of structural parameters on hydraulic performance of labyrinth channel emitters has been done. But most of them study the same type of labyrinth channel emitters,and the hydraulic performance comparison of different types of Labyrinth Emitter is less and less.This article selects the most common profile, rectangle, triangle and trapezoid labyrinth emitter as the research object. Then extract four kinds of channel structure parameters, and apply FLUENT software to simulate the water flow condition in the channel. The simulation conditions set3m,5m,7m of8kinds of pressure head, then we can respectively to get the velocity vector graph, velocity profile map of lateral section, static pressure distribution map, pressure distribution map of lateral section. And calculated the relationship of pressure and flow the relationship of pressure and reynolds number, flow coefficient, flow states coefficient,head loss coefficient, the pressure drop of unit channel length pressure drop, vortex strength and center velocity in the vortex. From the above aspects, the hydraulic performance of four types of labyrinth emitter is studied.We can draw a conclusion on the basis of numerical simulation and calculation results:1) Flow states coefficient can be used to evaluate the hydraulic performance of emitters,and the smaller that value is, the better that the hydraulic performance of emitters is. The flow states coefficient of profile labyrinth emitter is the smallest among four, so the hydraulic performance of which is better than the other three types of labyrinth emitter. The smaller the flow coefficient value is, the more stable the flow is. The profile labyrinth emitter has minimum flow states coefficient value, so the flow of which is minimum volatility and the most stable.2)Under the same condition of pressure head, reynolds number of four labyrinth emitters were greater than the critical Reynolds number of255, which explain the four types of labyrinth emitters is all in the turbulent state, and four labyrinth emitters has good energy dissipation capacity and the anti-clogging performance.3)The velocity vector diagram of four labyrinth emitters is compared that discovery:the water flow of four labyrinth channels has similar circumstances.Under the same pressure head, the number and position of vortex is different. Rectangle labyrinth emitter has3vortexes and the vortex volume is small. The other labyrinth emitters have4vortexes and the vortex volume is large. The vortex position of rectangular labyrinth emitter is located in the corner of the channel, and the vortex position of the other labyrinth emitters is near the channel wall.The vortex range of profile and triangle labyrinth emitter is greater than that of other two labyrinth emitters.4) The velocity distribution of profile labyrinth emitter in the specified section is very stable, which does not contain the vortex section.5) The head loss coefficient of the profile labyrinth emitter is larger than the other three kinds of labyrinth emitter. With the increase of the pressure head,the head loss coefficient of four labyrinth emitter decreases slowly.6) From three aspects compared that include the intensity, energy dissipation capacity as well as the center velocity of the vortex, vortex of the profile Labyrinth Emitter is relative to the others, which is not easy to cause clogging and has good energy dissipation capacity.7) Generally speaking, under the same longitudinal channel section area and shape as well as the same length channel of four labyrinth emitters conditions, hydraulic performance of the profile labyrinth emitter is better than the rectangular, triangular, trapezoidal labyrinth emitter...
Keywords/Search Tags:labyrinth emitter, channel structure, numerical simulation, hydraulic performance, vortex strength
PDF Full Text Request
Related items