Influence Of Position And Parameters Of Singleinternal Tooth On Hydraulic Performance Of Double Labyrinth Channels

Water resource is the origin of life and is indispensable for the survival of human being and the advancement of the world.However,water shortage is becoming extremely severe around the world,especially in China,which,coupled with the ever-increasingly serious water pollution,makes it an essential trend to greatly advocate the water-saving irrigation technique.As one of feasible and high-efficiency water-saving irrigation techniques at present,drip irrigation technique enjoys better ability to save water and energy and presents a better irrigation quality than other irrigation techniques.Thus it can improve the quality of crops.The structure and parameters of emitter can pose significant impacts on the irrigation quality.The advantage of the labyrinth channel emitter which is the mainstream emitter in current society lies in its complicated channel structure which can be used to add the head loss and finally achieve energy consumption.Therefore,labyrinth channel is widely applied.Inthe paper,the single internal tooth-based rectangle double-labyrinth-channels emitter is proposed which is formed by setting single internal tooth into the channel of labyrinth channel emitter widely used in the society.Physical modelling experiment and computational fluid dynamics software are performed on 4 kinds of single internal tooth-based rectangle double-labyrinth-channels emitters,with 12 different positions and 5 different heights of internal tooth forming 60 different combinations.Based on the experiment and calculation,the pressure-flow relation curve is obtained including the change law of flow stance index,flow coefficient as well as the Reynolds number.Specific conclusions are drawn as follows.1 The flow of single internal tooth-based rectangle double-labyrinth-channels emitter increases with the increase in pressure and decreases with the increase in height of internal tooth.2 After setting single internal tooth in part with or without vortex along the transverse channel of rectangle labyrinth channel emitter respectively,the flow stance index of emitter formed by setting single internal tooth in part with vortex is larger than that formed by setting single internal tooth in part without vortex,indicating that emitter formed by setting single internal tooth in part without vortex along the transverse channel of rectangle labyrinth channel emitter exhibits better irrigation quality and hydraulic performance than that formed by setting single internal tooth in part with vortex,no matter the single internal tooth is set in the up side,center or down side along the vertical channel.3 Emitter formed by setting single internal teeth with height of 0.7mm,0.9mm and 1.1mm in the right side along the vertical channel of double-labyrinth-channel emitter presents a smaller flow stance index compared with that formed by setting single internal teeth in the left side,indicating that under a given setting position of internal tooth along transverse channel and given height of 0.7mm,0.9mm and 1.1mm,emitter formed by setting single internal tooth in the right side along the vertical channel exhibits a better hydraulic performance than that formed by setting single internal tooth in the left side.4 Single internal tooth-based rectangle double-labyrinth-channels emitter formed by setting single internal tooth in the left side along vertical channel sees the flow stance index firstly increases then reduces as the height of single internal tooth increase.The flow stance index of emitter formed by setting single internal tooth in the right side along vertical channel firstly reduces and then increases with the increase in height of single internal tooth.5 The flow coefficient of single internal tooth-based rectangle double-labyrinth-channels emitter decreases with the increase in height of single internal tooth and is not affected by the change of setting position of tooth.6 We comprehensively compared the water velocity field of four different t ypes of douches of which teeth are added in three different positions along vertic al direction,the upside,the middle side and the downside,finding that when add ing teeth in upside along vertical direction,the ratio of vortex zone area to channel is larger than that in the case of adding teeth in middle side and downside alon g the vertical direction.It shows that douches which see teeth added in upside al ong vertical direction boost a better energy dissipation performance than those s eeing teeth added in middle side and down side along the vertical direction.