Design of Venturi-Type Fertilizer Injectors to Low-Pressure Irrigation Systems

Twenty prototypes of Venturi-type fertilizer injectors for low-pressure agricultural irrigation systems were designed based on functional hydraulic pressure head and variation of their structural designs. These prototypes were modelled in three dimensions (3D) and evaluated using simulation through Computational Fluid Dynamics software (CFD). The main structural design characteristics come from a real necessity to complement an low pressure multigate irrigation system project named in Spanish “El Manzano” (The Apple tree) and bring it the fertigation possibility. The aim of this research was to select the best prototype, in order to identify the convergent and divergent angles, throat diameter and hydraulic pressure head to efficiently produce a Venturi-type injector for use in gated-irrigation pipe irrigation systems for use in a future in “El Manzano” project. As a result of the simulations, the physical characteristics of the injector were defined. The inlet and outlet diameters should be 152.4 mm, the throat diameter 76.2 mm and the suction diameter of 50.8 mm. The convergent and divergent angles showing most improved performances were 7.5 and 10°, respectively. This methodology can be used to construct Venturi-type fertilizer injectors for low-pressure gated-pipe agricultural irrigation systems, which, on one side, can reduce significantly the fertilizer application costs and, on the other side, the fertilizer management efficiency can be also improve considerably to save water resources. There is relatively very little experience in using this type of fertilizer injectors in low-pressure irrigation systems.