Experimental Research On Spray Characteristics Of Micro-sprinkling Hoses With Low Water Head

Micro sprinkling hose is a kind of porous flow thin-soft plastic hose.A single irrigation emitter is composed of a few small holes according to certain rules.The emitters are laid equidistantly along the flow direction.The hoses are flattened when they are not filled with water.The water is ejected from the hole in the upper part of the hose which is filled with water,and then broken into water droplets due to the air resistance.Finally,the water droplets wet the ground and form a moist area.In the field of irrigation conditions,the water at the end of the pipeline is generally low,so the way that enhancing the spray uniformity by improving the water pressure is more difficult.In order to improve the irrigation effect of micro sprinkling hose,it is necessary to study the spray characteristics under low head conditions.In order to analyze the influence of water head,laying length and interval distance on spray characteristics of micro-spinkling hose in low water head between 1~5m,N45(45mm folding width)single-row 5 holes micro-spinkling hose was taken as the research object in the test.In the research,water distribution contour maps were made by the software Surfer and the characteristics of water distribution was analyzed based on the test data.The spray uniformity of the hose was evaluated by Christiansen Uniformity coefficient.Then,based on the distribution law of single-hose water distribution,the spray effect parameters of double-hose combination were calculated by superposition method.In the meantime,with the help of water distribution contour maps which were made by the software Surfer,the spray characteristics of the combination were analyzed in the conditions of different laying lengths,different water heads and different interval distance.The results of the research are as follows:(1)The software Surfer is a simple tool for drawing contours of water distribution,which can help researchers to understand the distribution of spray water in the wet area intuitively and provide a reference for the qualitative analysis of spray characteristics.(2)Water head and laying length have a significant effect on spray uniformity of a single micro-sprinkling hose along the direction.When the laying length is constant,spray uniformity of single hose increases with a increase of the water head.When the water head is constant,spray uniformity of single hose increases with a decrease of the laying length.(3)To ensure spray uniformity in the wet area,the laying length of a single N45single-row 5 holes micro sprinkling hose should not exceed 20 m when water head is less than 3m.When the water head is between 3~5m,the laying length of single hose should not exceed 40 m.Under the condition of the low water head,the laying length of the double-hose combination should not exceed 30 m.When the water head between 3~5m,the distance between two hoses should be between 4~6m.(4)To make micro sprinkling hose layout in the field more convenient,the distance between two hoses should not be too short.Therefore,when the water head between3~5m,the double-hose combination of single row 5-hole micro sprinkling hose with20~30m laying length can usually spray a range of 3 to 4 furrow.With the laying length being more than 40 m,the single row 5-hole micro sprinkling hose can be used as supplementary irrigation measures in the field.(5)Compared with sprinkler irrigation,the spray uniformity of the micro sprinkling hose is not high,so the spray uniformity evaluation criteria should be established to match the hydraulic characteristics of micro spinkling hose.When the water head less than 5m,the spray uniformity of a N45 single row 5-hole micro sprinkling hose should not be less than60%.(6)When the water head is very low(less than 1m),the hoses can be placed near the plant which could achieve similar effect to drip irrigation.Compared with drip irrigation and micro sprinkler irrigation,water saving cost of micro sprinkling hose is effectively reduced.The results of this research have a guiding role in optimizing the design parameters of micro sprinkling hose and rationally arranging field irrigation pipeline network.