Experiment On Flow Pattern In Labyrinth Emitter And Numerical Simulation Of The Pressure Field

Water is one of the most valuable natural resources which is the survival and development of human society; it is also a strategic economic resources and an important part of the country’s comprehensive national strength. With the development of economy and the population rapid increase, water shortage has become a worldwide problem that many countries and regions are facing in the world. Water shortages become important constraints of the current world economic and social development, therefore, water-saving technology has become increasingly urgent.China is a large agricultural country whose Agriculture accounts for73%of the total national water consumption, there is a serious contradiction between the agricultural water supply which is the bottle neck problem restricting China’s agricultural development, and therefore it is imperative to develop water-saving irrigation techniques. Drip irrigation technology is the most advanced and effective in many water-saving irrigation technology; but because of the fine structure complex and small size of drip irrigation emitters, the micro analysis about the internal pressure field in flow channel of drip irrigation emitters are less. This article through the experiment reaches a conclusion that the flow pattern can be regarded as turbulence or transition region in the runner of the labyrinth emitter; meanwhile I study the distribution of the internal pressure field in flow channel of labyrinth emitter by fluid dynamics software Fluent and provide some references to solve the problem of labyrinth anti-c logging.Combined with natural science fund project in Shanxi Province《The drip irrigation water sand two phase flow research》(2008011054), on the basis of a more detailed overview of the research results of drip irrigation emitters were studied by experiment and numerical simulation of the flow pattern and pressure field. To analyze the test results and numerical simulation results, the following conclusions can be drawn:(1) There is "low speed area" and whirlpool area in the runner of the labyrinth emitter; and "low speed area" will make the sediment particle here deposit;(2) The labyrinth path has great disturbance on the flow, making the laminar flow change into the turbulence flow when Reynolds number is small; on the whole, the flow pattern can be regarded as turbulence or transition region; therefore, the numerical simulation of the pressure field is in the turbulent flow in this paper;(3) Unlike the classical Reynolds test, the head loss in the labyrinth path is proportional to the2.0-2.5th power of average velocity of section; the flow pattern index of labyrinth emitter can be0.5below;(4) The critical Reynolds number of flow state conversion between transition region and the turbulence ranges from87.5to125.0in the test;(5) The numerical simulation results of the pressure field indicate that, in the same flow, the pressure of the labyrinth path centerline and energy loss are decreasing;pressure range and pressure are increasing with the flow area; (6) The numerical simulation results of the pressure field show that, in the same flow section, the pressure of the labyrinth path centerline and pressure range and pressure are increasing, the difference between the pressure maximum point of pressure across the high point is bigger and bigger; there is pressure point mutation in the whirlpool place, whose pressure sharply reduced;(7) There is negative relationship between velocity and pressure in the runner of the labyrinth emitter within the whirlpool along the Y-axis direction, labyrinth maze turning point of the lateral wall and the whirlpool centerline along the Y-axis direction; there is positive relationship between velocity and pressure in the runner of the labyrinth emitter within the whirlpool along the Y-axis direction, labyrinth maze turning point of the lateral wall and the whirlpool centerline along the Y-axis direction.