The Effect Of The Front And Rear Wear-rings Clearances And Shapes Of The Impeller On The Performance Of Submerged Pump

The submerged pump is the main circulating power for transporting corrosive chemical raw materials such as concentrated sulfuric acid,which is essential for the improvement of its performance and operational stability in the chemical industry production.In order to clarify the effect of the front and rear wear-rings clearances and shapes of impeller on the performance of the submerged pump,a centrifugal submerged pump with model of XDB?G?1800-18 was studied through the method of theory combining numerical simulation and experiment.1.The effect of wear-rings clearances and shapes on the external characteristics of submerged pumpWith the increase of the front wear-ring or the front and rear wear-ring,the capacity with optimal operating point of the submerged pump decreases.When only changing the rear wear-ring clearance,the flow of optimal operating point is around0.9 times the design flow.In the case of changing the front wear-ring the sensitivities of the external characteristics is higher.And the external characteristics are not sensitive to the rear wear-ring.Compared with the three toothed ring seal models,the zigzag ring model has the highest lift and efficiency.Under the standard flow rate conditions,compared with the flat-shaped wear-ring model that the front and rear wear-ring clearance are 0.5mm,the saw-toothed model is increased by 0.54%and the efficiency is increased by 0.29%.Compared with the original model,the lift of the saw-toothed model increased by 10.94%and the efficiency increased by 3.52%.2.The effect of wear-rings clearances and shapes on the leakage of submerged pumpThe leakage of the rear wear-ring is basically equal to the leakage of the overflow hole.When the clearance values of the front ring and the rear ring are equal,the leakage of the front wear-ring clearance is greater than the leakage of the rear wear-ring clearance and the overflow hole,that is because the leakage of the front wear-ring clearance is internal leakage and the rear wear-ring connected to the overflow hole is for external leakage.That is also related to overflow hole's position.Compared with the original model,the leakage of the front and rear wear-ring of the toothed wear-ring models are significantly reduced and the saw-toothed wear-ring model has the least amount of leakage.In the condition of design flow,the leakage of the front wear-ring of the saw-toothed wear-ring model is reduced by 58.03%and the leakage of the wear-ring is reduced by 38.99%compared with the original model.3.The influence of wear-rings clearances and shapes on the the flow characteristics in the wear-ringsWhen only the front ring gap increases,the dynamic pressure value of the front wear-ring decreases.It can be seen that when the flow cross section and the gap leakage amount increase simultaneously with the gap value,the former influence is more prominent.The dynamic pressure value in the front wear-ring clearance decreases with the increase of front wear-ring clearance,which indicates when the cross-section area and the leakage of the wear-ring clearance increases at the same time,the former influence is more prominent.The dynamic pressure of the model with the rear wear-ring clearance less than 1mm has a sudden drop and the static pressure reaches a minimum at the monitored section 12 taken when only the rear wear-ring clearance is changed or the front and rear wear-ring clearance are changed at the same time.And the the rear wear-ring clearance,the more obvious the dynamic pressure drop.In the front wear-ring clearance of each model in which the wear-rings clearance and shape modifications is mainly caused by the change of the hydrostatic pressure,and the dynamic pressure is almost unchanged.The fluid inside the wear-ring of the toothed ring model is subjected to greater hydraulic resistance so the consumption of static pressure is increased.4.The Effect of the wear-rings clearances and shapes on the flow characteristics in the impeller side chamber of submerged pumpThe variation of the static pressure in the anterior chamber of each modelunder wear-rings clearance modification was significantly smaller than that in the corresponding posterior cavity.As the front wear-ring clearance increases,the static pressure in the front and rear impeller side chambers decreases significantly.And the rear wear-ring clearance is increased,and the pressure of the balance chamber is obviously increased.The change of u_t/u which is called dimensionless tangential velocity in the front and back cavity of each model with different clearance changes can be divided into three stages,where in the stable area of the front cavity flow is longer than the back cavity.Only adjusting the rear wear-ring clearance,the trend of the u_t/u called dimensionless radial velocity and turbulent kinetic energy in the front and back cavities of the model with the rear ring gap of 1.3 mm is different from other models.It can be seen that the larger the back ring gap,the greater the influence in the pump cavity.It can be seen that the larger the rear wear-ring clearance,the greater the influence in the impeller side chamber?In the toothed ring model,there are pairs of vortexes in the outer flow channel of the double volute of the submerged pump,which is closer to the center of the volute section.When the fluid flows out of the impeller and enters the volute,the fluid in the volute receives less eccentric flow,so the energy loss becomes smaller which can effectively improve the efficiency of the pump.5.The effect of the wear-rings clearances and shapes on axial thrust of submerged pumpThe axial force is slightly increased when only the front wear-rings clearance is reduced in the design conditions and The main reason is the force F₁ named the outer surface of the impeller cover increases.Thedirection of F₁ points to the front shroud.The larger the front and rear wear-rings clearances,the smaller the flowing resistance in the clearance so the slight decrease in the force on the front and rear wear-rings.Among the three toothed wear-ring models,the saw-toothed wear-ring model has the best balance of axial force and compared with the original model,the axial force is reduced by 52.15%.The fluid is deformed by the shearing force from the outer wall surface of the toothed impeller ring,then occurs deformation flow.At the same time,the outer surface of the toothed wear-ring produces a force that hinders the deformation of the fluid.Therefore,compared with the original model,the surface forces of the front and rear wear-rings are significantly increased.