Study On Influence Of Impeller Back Blade On Axial Force Characteristics Of Centrifugal Pump

Balancing the axial force of the centrifugal pump with the back blade is a relatively common balancing method,especially in the centrifugal pump and impurity pump conveying the impurity-containing liquid.However,installing the back blade will increase the pump's energy loss and cause th e pump's efficiency to drop.In order to research the effect of impeller back blade on axial thrust of centrifugal pump,the IS80-50-315 type centrifugal pump whose speed had been reduced was taken as the research object.Thirteen different schemes are des igned by a change of the number and width of impeller back blade of centrifugal pump,the pump performance,front and rear pump chamber pressure in every scheme is tested and analyzed,relation curve of pump chamber pressure and axial force with the width of back blade is obtained.The main contents and conclusions of this article are as follows:1.The test and simulation results show that after the back blade is mounted on the back of the centrifugal pump impeller,the overall performance of the pump is gr eatly affected.Compared with the performance of pump without the back blade,the head and input power of the pump are obviously increased,but the efficiency is reduced when the back blade is installed.The greater the width and number of the back blades,the more pronounced the effect on the test pump.2.From the liquid pressure curve diagram of the pump chamber and the pressure diagram of the pump chamber pressure,it can be known that the changes in the width and number of the back blades have little effect on the liquid pressure in the front pump chamber,but the back blade has a great influence on the liquid pressure in the rear pump chamber.After the back blade is installed,the pressure in the rear pump chamber drops significantly,and a eddy appears between the two back blades to form a local low pressure area.As the back blade width increases,the liquid pressure in the rear pump chamber gradually decreases.3.The back blade changes the axial force by changing the liquid pressure of the rear pump chamber.When there is no back blade,the rear pump chamber has a greater liquid pressure than the front pump chamber,and the positive direction of the axial force is the direction of the suction inlet of the impeller.After installing the back blade,when the width of the back blade increases to a certain value,the magnitude and direction of the axial force will change.When the number of back blade is equal to 5and the width is 3.5milimeters,the axial force is smaller and the change range is smalle r with the increase of flow rate.From the perspective of balance axial force,Z is equal to 5 and t is equal to 3.5 milimeters are the best.4.The back blade width is a key factor affecting the axial force coefficient C_F.When the back blade number is fixed,the axial force coefficient gradually changes from a positive value to a negative value with the increase of the back blade width.When the back blade width t<5mm axial force coefficient decreases slowl y with the increase of the back blade width.When the back blade width t>5mm,the axial force coefficient decreases sharpl y with the increase of the back blade width.Among them,when the number of back blades is 5 and the width is 3.5 mm,the axial force coefficient is the smallest and positive.The abi lity of the back blades to balance axial forces becomes more pronounced as the width of the back blades increases.5.The numerical simulation of the test pump was carried out under different schemes.The internal flow field of the pump chamber was analyze d based on the simulation results.The results showed that:The effect of the back blade on the performance of the pump,the pressure of the front and rear pump chambers and the axial force was basically consistent with the test res ults and the simulation results.The research results have high credibility.6.The research results preliminarily revealed the influence mechanism of the impeller back blades on the performance of the centrifugal pump,the pressure characteristics of the pump chamber,and the axial force characteristics,and provided important references for optimizing the design of the back blade structure.It is a very important contribution for the design and development of centrifugal pumps.