Analysis Of The Characteristics Of The Unsteady Flow And Study On The Structural Design Of Spiral Tube Centrifugal Pump

The spiral tube centrifugal pump,that is,the spiral tube pump,is a new type of special purpose pump.Its rotor is a spiral tube body.Under the same design flow rate,compared to the traditional vane centrifugal pump,the spiral tube pump has a higher outlet flow rate.In addition,with low pressure pulsation and low noise,it is expected to be applied to underwater propulsion vehicles,thereby greatly improving the speed and stealth performance of submarines.With the development of centrifugal pumps towards high speed and high power,vibration and noise have become important performance indicators for the design of centrifugal pumps.Judging from the previous data,both the simulation results and the experimental results show that the head and efficiency of the spiral tube pump are low,which has a certain gap with the results of theoretical analysis.This may be caused by a certain irrationality in the structural design of the spiral tube pump.In this paper,the internal flow field and pressure pulsation of the spiral tube pump under different flow rates are deeply studied through the unsteady constant value simulation of the internal flow of the spiral tube pump,and the unsteady flow characteristics of the spiral tube pump are initially revealed.The indefinite constant value simulation of the internal flow of the spiral tube pump,the in-depth study of the influence of the structural parameters of the spiral tube on the internal flow field and pressure pulsation of the spiral tube pump,through the orthogonal experiment of the spiral tube pump,the effect of the structural parameters of the spiral tube body is explored.The influence of the head and efficiency of the spiral tube pump is expected to provide a reference and basis for the design and structural improvement of the spiral tube pump,so as to guide the design of a higher performance spiral tube pump.The main conclusions drawn in this paper are as follows:（1）The simulation results of the non-constant value of the internal flow field of the spiral tube pump under different flow rates show that the size of the flow rate has a great influence on the streamline direction of the volute diffusion section of the spiral tube pump.The profile of the volute diffusion section is difficult to adapt to different flow rates.Therefore,the volute design of the spiral tube pump needs new theoretical support.With the increase of flow rate,the spiral tube body cavitation tendency of the spiral tube pump is more obvious and the spiral casing outlet of the spiral tube pump has a greater pressure.The size of the flow rate also has a great influence on the pressure pulsation of the spiral tube pump volute and the spiral tube body.With the increase of the flow rate of the spiral tube pump,the pressure pulsation of the spiral tube pump volute shows an upward trend,and with the increase of the flow rate The pressure pulsation of the spiral tube body first increased by a large margin and then decreased by a small margin,and the pressure pulsation as a whole was on the rise.（2）The comparative analysis of the simulation results of the unsteady constant value of the internal flow of the spiral tube pump with different numbers of elbows shows that the increase in the number of elbows Z of the spiral tube body makes the outlet of the spiral tube pump volute more pressure.At the same time,the spiral tube pump with Z=5 has a smaller negative pressure area in the spiral tube body elbow and a better pressurization effect.The number of elbows has a greater influence on the pressure pulsation of the spiral tube pump volute and the coil body.,Z=5（inlet and outlet area ratio（?）_A=0.8）and Z=4（（?）_A=0.64）spiral tube pump,the pressure pulsation of the volute and spiral tube body is smaller than that of Z=3（（?）_A=0.48）,and The heads are increased by 25.6%and 22%respectively,and the minimum efficiency is 43.4%when the number of elbows is Z=4.（3）The comparative analysis of the simulation results of the unsteady constant value of the flow inside the spiral tube body with different outlet diameters of the elbow shows that increasing the outlet diameter of the elbow body can increase the outlet pressure of the volute.As the outlet diameter of the elbow increases,the volute pressure pulsation of the spiral tube pump decreases,and the spiral tube body of the spiral tube pump with D₃=16mm has smaller pressure pulsations.At the same time,the head and efficiency of the spiral tube pump with（?）_Aof 0.81（D₃=17mm）are the largest,which is16%higher than that of the spiral tube pump with（?）_Aof 0.56（D₃=15mm）and the spiral tube with0.64（D₃=16mm）of（?）_Apump efficiency increased by 5.3%（4）Orthogonal test of the spiral tube pump shows that:for the head of the spiral tube pump,the number of elbows has the greatest influence,the outlet installation angle of the spiral tube body has the least influence,the inlet diameter has the greatest influence on the efficiency of the spiral tube pump,and the inlet diameter of the elbow It has the least impact on the efficiency of the spiral tube pump.Therefore,in the design of the spiral tube pump,the number of elbows can be appropriately increased and the inlet diameter of the spiral tube body can be reduced,thereby improving the external characteristics of the spiral tube pump.