Study On Spraying Characteristics Of Micro Spray Tape Under Longitudinal Structure Optimization

Micro spray tape irrigation is a new type of efficient water-saving irrigation technology that has emerged in recent years,with the advantages of water conservation,low cost,ease of use,etc.The application prospects are very wide.However,the number of spray holes along the longitudinal direction（longitudinal）of the traditional micro spray tape remains unchanged,and its spraying uniformity along the longitudinal direction will be significantly reduced,resulting in poor overall spraying effect.This study attempts to change the distribution of the number of spray holes along the longitudinal direction of the micro spray tape to study the changes in the spraying characteristics of the micro spray tape under the optimization of the longitudinal structure,which has not been reported in the relevant studies.The results of this study are of theoretical and practical significance for the enrichment of micro spray irrigation theory and the optimization of micro spray production.Five types of micro spray tapes were designed and tested under four working pressures（25 k Pa,30 k Pa,35 k Pa,40 k Pa）with a fold diameter of 42 mm and a total length of 40 m.The oblique 3 holes（CK）as a control group of micro spray tape,the end of the transformation to oblique 5 holes for different proportions of the total length of the longitudinal structure optimization test control(1/4,2/4,3/4,4/4 of the total length are numbered:T_1/4,T_2/4,T_3/4,T_4/4).The results and conclusions of the study are as follows:（1）The larger the proportion of oblique 5-hole micro spray tape,the larger the head loss along the end of the micro spray tape,the smaller the single-hole flow.4 working pressure T_1/4,T_2/4,T_3/4 end of the pressure,single-hole flow rate compared to the first end,the magnitude of the reduction in the basic respectively:32%～38%,50%～52%,52%～54%between;single-hole flow rate reduction respectively:20%～28%,25%～32%,32%～35%.Therefore,the structural ratio is the main reason that affects the end pressure and single-hole flow rate drop of the micro spray tape.（2）The use of SPSS to optimize the structure of the micro-jet with the head loss and pipe head flow in accordance with the general formula for head loss along the polyethylene pipe parameter fitting,in the 95%confidence interval,the fit is 0.939.but the micro spray tape as a kind of along the drainage tape,the fitted parameter values are different from the polyethylene tape.Through the calculation found that this is due to the micro spray tape in the direction of the length of the tape spraying water intensity caused by the larger.（3）By establishing the relationship between the pressure of the micro spray tape and the single-hole flow rate,the empirical formula for the single-hole flow rate of the micro spray tape was determined with the relevant parameters of the theoretical formula.It is found that with the increase in the proportion of oblique 5-hole micro spray tape,the flow index of water flow in the micro spray tape first decreases and then increases,using SPSS fitting found that when the length of the oblique 5-hole micro spray tape accounted for 57%,the flow index is the smallest,at which time the flow index is 0.382.CK and T_4/4 along the length of the flow coefficient and the distance from the head of the tube in line with the quadratic function relationship between T_1/4,T_2/4,T_3/4 The flow rate coefficients fluctuate between 0.684 and0.847.（4）According to Christian uniformity coefficient method to calculate the spray uniformity of the micro spray tape,found that T_2/4,T_3/4 in the working pressure does not exceed 35 k Pa,to ensure that the first end of the micro spray tape spray uniformity in more than 56.5%;T_1/4 end spray uniformity by the pressure will produce large fluctuations,while T_2/4,T3/4 end of the spray uniformity by the pressure is small,with better spraying uniformity.Therefore,by appropriately increasing the working pressure and the number of spray holes added to the end of the micro spray tape to increase the spray uniformity of the micro spray tape.（5）On the basis of the spraying water volume of a single micro spray tape,the cubic spline interpolation method is used to interpolate the water volume distribution along the tape length,and then the direct superposition method is used to simulate the spraying uniformity of micro spray tapes under different assembly spacing.Simulation shows that with the increase in the combination of spacing,the trend of gradually reducing the intensity of spraying water between the two micro spray tape,the drying area gradually increased;T_1/4 spraying uniformity gradually reduced,T_2/4,T_3/4 spraying uniformity first increased and then reduced.Therefore,when the proportion of oblique 5-hole micro-spray tape is small,should be appropriate to reduce the combination of spacing,reduce the spraying range of oblique 3-hole micro spray tape dry area to increase the uniformity of spraying;when the length of oblique5-hole micro spray tape accounted for a relatively large,should be appropriate to increase the combination of spacing,reduce the end of the micro-spray tape spray water distribution intensity,to increase the uniformity of spraying.Through a comprehensive analysis of the full text,the front end of the oblique 3-hole end of the oblique 5-hole micro spray tape conditions,the oblique 5-hole micro spray tape accounted for 1/2 of the total length of the micro spray tape,micro spray tape spraying characteristics of the best.By improving the longitudinal structure of the micro spray tape,the overall spraying effect of the micro spray belt can be improved.