| The high-speed salvage pump studied in this paper is mainly used to cope with water problems in cities such as floodwaters.Due to its features of portability and strong water delivery capacity,it has been widely used in the rapid response to the solution of urban water accumulation.The axial flow pump was selected as a prototype.In order to achieve the technical goal of portability and retaining the water delivery capacity,the structure is designed to be more compact,and the method of using a permanent magnet frequency conversion motor is used to increase the pump rotation speed to ensure the water delivery capacity.At present,there are few researches on this type of salvage pump.Based on the theoretical analysis,the characteristics of internal flow in the pump was analyzed,and the experiment has been done to verify the applicability of the similarity law under variable operating conditions and predict cavitation flow field and solid-liquid two-phase flow law.The main research contents are as follow:?1?The three-dimensional modeling software was used to model the salvage pump,and the meshes for the calculation domain were generated by ANSYS ICEM.Based on CFX 15.0,the full flow field was calculated at the design speed and different flow conditions.The results of the external characteristics test are in good agreement with the numerical simulation ones,which shows that the numerical simulation has higher accuracy and reliability.Steady simulation was carried out at different speed operating conditions to analyze the influence of speed on performance.The results showed that the Head was in line with the similar conversion laws within a certain range.This is due to the fact that the leakage loss in pumps at different speeds cannot fully meet the similarity law.?2?Based on the steady calculation results,unsteady simulation for the full flow field under different flow conditions are carried out to analyze pressure fluctuation at each monitoring point in the time and frequency domain.The main pressure fluctuation at the inlet of the impeller and at the outlet of the vane is the blade passing frequency,and the main frequency of pressure fluctuation at the impeller outlet rim side is the vane blade passing frequency.?3?For the solid-liquid two-phase flow field of the salvage pump,the DPM model is used to simulate the different conditions of the particle conditions with different physical properties and the Mixture model is used to calculate the particle conditions with different concentration.The results are compared with the ones under the clean water conditions to obtain the influence on the external characteristics of the pump.The distribution of solid-phase particle distribution,shear stress and the distribution of solid-phase particle slip velocity under different schemes are analyzed,and the distribution of wear areas at the surface of overflow components is predicted.The results show that the effect of solid particle density on the pump performance is more significant than the particle size.The distribution of solid particles is mainly in the hub side and the vicinity of the exit on the impeller's working face.?4?Based on the ZGB cavitation model and the mixed two-phase flow model,the cavitation flow field is calculated,and the cavitation characteristics curves can be obtained under different flow conditions(0.8Qopt,1.0Qopt,1.2Qopt).The cavitation flow in the impeller with different cavitation number under different flow conditions is studied.The distribution of the bubbles in the impeller is analyzed to obtain the variation law of the blade load on the rim side of the blade.The cavitation flow field characteristics in the tip clearance region are analyzed under the small flow conditions. |
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