Analysis on hydraulic performance of bidirectional flow channel of drip irrigation emitter

Abstract: The bidirectional flow channel is a new kind of channel for drip irrigation emitter, it has the advantages of simple structure, easy manufacturing and good hydraulic performance. The main working principle of the bidirectional flow channel is mixing the forward flow and the backward flow to enhance the effect of energy dissipation. The forward flow and backward flow are produced by splayed wall and V-shape wall in the channel. In order to study the effects of structural parameters on hydraulic performances, choosing 9 key factors from the structural parameters and arranging 12 experimental schemes to study flow index and flow coefficient. The experiments can obtain the inlet pressure of channel and the outlet flow rate. Each experimental scheme was set 3 repeats to make sure that the results are accurate. Based on the flux of bidirectional flow channel under different pressures, the flow index and flow coefficient can be obtained by using linear regression, and then regression equations can be built. The regression equations regressed by the multivariable regression method about flow index and flow coefficient to 9 structural parameters have the higher relativity, the correlation coefficients are 0.999 and 0.998. The regression equations are verified by another experimental scheme which number is 13. The results showed that the regression equations are reliable and accurate. The flow index of bidirectional flow channel is in the range from 0.40 to 0.47, whose hydraulic performance is good. According to the t-test analysis, all of the 9 structural parameters are the important factors to the flow index at the 0.05 significance level, in which α, the field angle of V-shape wall is the most important factor, and followed by c, the distance between the vertex of V-shape wall and the medial of the side wall at the outlet; d1, the distance between the both sides of V-shape wall and the side wall of channel; β, the field angle of splayed wall; b, the width of inlet; d4, the distance between the vertex of V-shape wall and the vertex of splayed wall; d3, the width of the middle orifice of splayed wall; a, the width of outlet; d2, the distance between the both sides of splayed wall and the side wall of channel. There is a negative correlation between d1, a, b, β, c and flow index, while there is a positive correlation between other four factors and flow index; the outlet width and the field angle of splayed are the important factors to the flow coefficient, while the outlet width is the most important factor, there is a positive correlation between these two factors and flow coefficient. These conclusions can provide an evidence for designing bidirectional flow channel and make the hydraulic performance of the new channel better.