Study On Hydraulic Performance Of Screen And Disc Filters For Drip Irrigation

As an efficient water irrigation technology,drip irrigation is an effective way to achieve the goal that can save irrigation water and fertilizer.However,the narrow channel and complex structure always make emitters easily to occur clogging.As the key equipment of the drip irrigation,the performance of its work would affect the whole system.In this paper,the hydraulic performance,filtering capabilities and numerical simulation of four kinds of filter including screen filter and disc filter were studied.Hydraulic performance test under the seven flow rate;During the filtering capabilities test,3 kinds of sediment concentration(250 mg/L?340 mg/L?440 mg/L)and 3kinds of flow rate(1.5 m3/h?3 m3/h?4.5 m3/h)were choosed.Also,the filtering capabilities test about the water with fertilizer were texted.Then numerical simulation of screen filter and disc filter were studied using the standard k-?model with FLUENT.Then the following main conclusions were reached.(1)Through the hydraulic performance test about 4 filters,the results showed that under clean water conditions,the filter's head loss increased with the increase of the flow that could be described with a quadratic parabola,head loss of filter's with larger mesh number was greater when the flow rate was constant.(2)The numerical simulation result of hydraulic performance showed that the velocity distribution on the filter element was is very uneven,which will lead to the particulate that be filter distribution not homogeneous,reduce the filtering capabilities of filter element;The head loss of filter mainly caused in the joint of core and inlet or outlet.The structure of the inlet and outlet can be improved and optimized to be a less head loss.The velocity distribution along the direction of barrel length were decreased.There was almost zero above the bottom,particulate easily stayed there,so regular cleaning is very necessary.(3)The texts about filtering capabilities with muddy water showed that :under muddy water conditions,the filter's head loss was related to the flow variation and sediment concertration.With the increase of flow and sediment concertration,the higher the initial head loss was,the shorter the filtration cycle was.Under the same conditions,the disc filter's head loss and sediment removal rate were both obviously higher than the screen's.(4)The texts about filtering capabilities with fertilizer water showed that the screen and disc filter work fine when nitrogen and potassium irrigation used.Phosphate irrigation will lead to a serious clogging which is caused by physics and chemistry.The fertilizers concentration will decrease after water flow through the filter.So we need to clean the filter normally in order to make sure the adequate fertilizers into the field.solid particle was not distributed uniformly on the filter elements.The structure should be optimized to improve the performance of the filter.(5)Using the FLUENT to achieved structure optimization,the results showed that the head loss of filter and the distribution of velocity can be changed by changing the angle between inlet and outlet and the barrel.When the angle of screen filter was 90°,the head loss was reduced while the velocity distribution was more uniform;when the angle of disc filter was 90°,the head loss wasn't significantly reduced,but the there's no more vortex.