Study On Optimization Design And Internal Flow Of Two-stage Submersible Pump For Coal Mine

Mine multistage pumps are designed for low specific centrifugal pumps to get high head since they are usually applied in mine drainage and disaster relief situation.The transport medium usually contains sediment,slime,coal,cinder,fiber and other insoluble solid phase mixed sewage,therefore,no clogging performance was necessary for mine submersible pump.Built-in pump,the water flows through the motor sandwich,in order to get smooth shaft power curve and extend the service time of pump,it should be with no-overload performance.In the present paper,BQS25-150/2-30/N type two-stage mine submerge pump was taken as the research object,the hydraulic design of which was combined with no-overload sewage pump.The optimization of impeller blades and blade outlet angle were carried through the combination of theoretical analysis,numerical calculation and experiments.Meanwhile,the unsteady flow characteristics and solid-liquid two-phase flow characteristics of the pump are analyzed.The main contents and results are as follow:(1)Through the initial hydraulic design to obtain the key size of impeller,while ensuring the other parameters remain unchanged,through the optimization design of impeller blades numbers to get conclusion:the three-blade impeller is superior to double-blade and the four-blade impeller in no-overload performance and internal flow.(2)Under the condition of ensuring other geometrical parameters unchanged,the blade outlet angle was optimized and designed for 12 °16 °20 ° and 24 °.Through numerical simulation:with the blade exit angle increasing,the head and shaft power increased.Based on the analysis of internal flow field,with the outlet angle of impeller blade increasing,the impeller inlet low pressure area was obviously enlarged,and the high pressure area of impeller outlet was reduced,the flow channel vortex increased.Therefore,comprehensive performance of the option with ?2 = 12 ° was optimal,and the experiment of external characteristic was carried out.In addition,based on the numerical results of the different blade outlet angles,the Storola slip formula is modified.(3)The unsteady internal flow of three blades two-stage mine pump with various blade outlet angles were calculated,the fluctuation characteristic of the outlet of impeller,inlet of guide vane,the cross section of volute and the tongue were obtained under design condition.Meanwhile,the pressure fluctuation characteristic of ?2=12°was carried out under various working conditions.In addition,the radial force of the first and final stage impeller were studied,which provides some reference for the optimization of the vibration characteristics of the pump.(4)In order to analyze the solid-liquid flow in two-stage mine centrifugal pump,taking the project of Z=3,?2=12° as an example,the two phase flow in pump with variable size(0.5mm,0.8mm,1.0mm)particle under design point was simulated.The variation of external characteristic,distribution of particle mass concentration and wall shear stress in both guide vane and first impeller were analyzed,also,the trajectories of particles under different operating point(0.5Q,1.0Q,1.5Q)were compared when the particle diameter was 1.0mm.This part can provide a basis for improving the wearing performance of pump.