Abstract In order to study the relationship between the injection performance and the structural parameters of Venturi injector used in micro-irrigation system, injection performance tests of a kind of Venturi injector with four types of replaceable throat parts were conducted under inlet pressures of 0.10, 0.15, 0.20, 0.25 and 0.30 MPa, respectively. The results show that both the critical and maximum pressure differences are in positively linear relation with the inlet pressure. The inlet flow rate of the Venturi injector increases with the increasing of the inlet pressure or the difference between inlet and outlet pressures. As the ratio of outlet pressure to inlet pressure is less than 0.4, the ratio of injection rate to outlet flow rate increases with the decrease of the throat diameter and the increase of both the contraction and diffusion angles. As the ratio of outlet pressure to inlet pressure is greater than 0.4, the ratio of injection rate to outlet flow rate changes in an opposite trend. The established regression models describing the relationship between injection performance, throat geometry and working parameters can be used for design and operation of Venturi injector.
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