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| Numerical simulation of cavitation characteristics of Venturi injector |
| CHENG Qian, HUANG Xiuqiao, LI Hao, HAN Qibiao |
| Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences/Key Laboratory of Water-saving Agriculture of Henan Province, Xinxiang, Henan 453002, China |
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Abstract The cavitation characteristics of one post-optimized Venturi injector were investigated by numerical simulation, in order to explore declination in the injection performance caused by cavitation and to reveal the mechanism of energy loss in the flow field of Venturi injector. Results show that when the pressure difference across the Venturi increases, the suction pressure decreases continuously and the suction flow rate rises. Once the suction pressure decreases to the minimum, the suction pressure will keep constant, so does the suction flow rate. Then if the pressure difference is increased further, cavitation will occur in the junction between the throat and the diffuser firstly, and then and expand downstream gradually along the diffuser wall. By contrasting the total hydraulic heads at various cross-sections along the Venturi injector axis at different pressure conditions, the energy loss at the throat increases with increasing pressure difference, but it is about half the total energy. Once the cavitation occurs, the energy loss at the throat will keep constant, while the energy loss across the diffuser will be enlarged. This is because cavitation development can deteriorate the flow condition in the diffuser and produce large-scale vortices around the cavities, which consume even more energy. The increased energy consumption results in a sudden and rapid decrease in the injection efficiency.
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Received: 05 July 2017
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