Design and installation alternatives of Venturi injectors in drip irrigation

The performance and installation alternatives of four Venturi injector prototypes were studied at Universitat Politècnica de València, Valencia, Spain (39°29' N; 0°23' W; 20 m). This device performance was studied under several parameters such as head loss, relation of flows and injection efficiency. The installation configurations analyzed were: without the injection of nutrients solution and with the injection either having negative or positive pressure at the Venturi throat. The inlet pressures were established between 10 and 40 m.w.c. The experimental data has been processed using multiple stepwise regression techniques and analysis of variance (ANOVA). Moreover, geometry integration versus diameters, flows and pressures is used to obtain some equations for predicting the head loss and injected flow. The results of the present study showed that the relation between flows and injection efficiency were better when the diameter of inlet nutrient line increases and become worse when decreases the diameter of the Venturi throat. Accordingly, these dimensions become very important in the design prototype and installation configuration. Furthermore, after the analysis of laboratory experiments it can be concluded that head losses, at the same injected flow, were lower if the injection was carried out with positive pressures at the throat than in the case of negative pressures. Also in this case, the relationship between flow rates and injection efficiency leaded to a good performance of the proposed installation.