| Bidirectional submersible flow pump is a new type of pump device,and the overall structure is compact,the overall efficiency is high,the area is small and the flow channel is straight.With the construction of many large-scale diversion and drainage projects,the bidirectional submersible flow pump has been paid more and more attention because of its own characteristics,and more and more researches have been made on improving and optimizing the hydraulic performance of bidirectional submersible flow pump.In practical engineering,the guide blades on both sides of most bidirectional flow pump devices adopt bent guide blades or one side of bent guide blades and one side of straight guide blades,and the guide blades remain fixed as a whole.In this way,the positive and negative operating conditions cannot be taken into account.The existing bidirectional submersible flow pump with adjustable guide blades can further improve the operating conditions of the pump device by adjusting the guide blades on both sides so as to improve the overall efficiency.Previous studies have been made on the influence of the Angle adjustment of the trailing guide vane on the bidirectional submersible flow pump.Based on this,the further study on the influence of the Angle adjustment of the front guide vane on the hydraulic performance of the bidirectional submersible flow pump has a certain reference and application significance for practical engineering.In this paper,on the basis of ensuring that the Angle of the rear guide vane of the adjustable guide vane submersible flow pump remains unchanged,the forward guide vane inlet Angle of the pump device is adjusted,and the influence of the Angle adjustment of the front guide vane on the overall hydraulic performance of the bidirectional submersible flow pump is studied.CFD numerical simulation software was used to perform positive and negative numerical calculations on the pump device under five kinds of pre-guide vane placement angles(Zα=-20°、-10°、0°、10° and 20°),and three characteristic working conditions were compared(forward:0.85 Qd=220 L/s、Qd=270 L/s、1.15Qd=320 L/s;Reverse:0.85 Qd=250 L/s、Qd=290 L/s、1.15 Qd=330 L/s)the hydraulic performance,internal flow field and entropy production of each flow component inside the pump unit were summarized and analyzed.At the same time,multiple monitoring points were arranged in the impeller and the guide vane on both sides to collect pressure pulsation data for comparative analysis.Finally,the reliability of the numerical simulation is verified by the model test conducted on the hydraulic test bed of Yangzhou University.The numerical simulation results show that in forward operation,the pump head gradually increases with the negative Angle change of the front guide vane,and the efficiency increases first and then decreases when Zα=-10°,the maximum efficiency is 66.7%.In reverse operation,the head and efficiency of the pump device increase gradually with the negative Angle change of the front guide vane,and the maximum efficiency is 68.8%in the design condition when Zα=-20°.By analyzing the hydraulic performance of each part inside it,it can be found that the main hydraulic loss occurs in the outlet passage,while under positive and negative operating conditions,the hydraulic loss gradually decreases as the front guide vane Angle changes to the negative Angle,and the internal flow pattern is obviously improved.Through the observation of the pressure pulsation at each monitoring point,it can be found that the influence of the front guide vane Angle adjustment on the main frequency of the pulsation is not obvious,but has an obvious improvement on the low frequency pulsation,especially the rear guide vane outlet and its water outlet side.Finally,the reliability of the digital model is verified by comparing the actual data collected through the model test. |
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