| The impeller with double seal rings can effectively balance most of the axial force of the centrifugal pump.The leakage of the centrifugal pump directly determines the magnitude of the axial force,and the leakage is influnced by the inner diameter of the balance hole and the radial clearance,diameter and axial length of the rear seal ring.Therefore,the research on the flow characteristics of the pump cavity and the influence of leakage with different radial clearance and diameter of the rear seal ring matched with different inner diameter of the balance hole is of great significance.In this paper,80-50-315 centrifugal pump as the research object,through the method of test and numerical calculation,the influence of different balance hole inner diameter matching different rear seal ring radial clearance and diameter on centrifugal pump performance,pump cavity pressure,leakage and axial force is analyzed.The research content of this paper is as follows:1.In order to change the inner diameter of the balance hole and the radial clearance of the back-sealing ring without changing the impeller,the movable back ring and the balance hole sleeve are specially designed.Under different inner diameter of the balance hole and the radial clearance of the back sealing ring,the performance and the pressure of the pump chamber are tested.Dimensionless pressure coefficient(?)and the specific area (?) are introduced.The results show that increasing the radial clearance of the rear sealing ring or the inner diameter of the balance hole;the head and efficiency of the pump are decreased and the power is increased.The liquid pressure in the front pump cavity has no obvious change;and the liquid pressure in the rear pump cavity is decreased,but the influence of the change of the radial clearance of the rear sealing ring is greater than that of the inner diameter of the balance hole.The liquid pressure of the balance chamber increases with the increase of the radial clearance of the seal ring,and decreases with the increase of the inner diameter of the balance hole.The relation curve between the pressure coefficient(?)and the specific area (?)of the balance chamber is nonlinear,the specific area (?)increases,and the pressure coefficient P decreases.The best range of the specific area (?)is 2.5~4.44.2.Aiming at the problem that the leakage of the back seal ring is difficult to measure,the method of adjusting the liquid pressure of the balance chamber is proposing to measure the leakage of the back seal ring,and the dimensionless leakage coefficient ?_m and the head coefficient ? are introducing.The analysis results show that the leakage of the back sealing ring increases with the increase of the radial clearance of the back seal ring or the inner diameter of the balance hole,but the leakage of the back seal ring increases with the increase of the radial clearance of the back-sealing ring.The influence degree is far greater than the inner diameter of the balance hole;when the radial clearance of the back seal ring is 0.2mm,the leakage is far less than other clearances.Under different head coefficients,the leakage coefficient ?_m changes with the specific area in accordance with the same law,which provides a reference for the calculation of the leakage of similar pumps,the specific area increases and the leakage coefficient decreases.3.The three-dimensional models of the inner diameter of the different balance holes,the radial clearance of the rear seal ring and the diameter of the rear seal ring are calculated.The results of the numerical calculation are comparing with the test results,which verify the feasibility and accuracy of the numerical calculation method.The analysis and calculation results are as follows:under the different inner diameter of the balance hole,increase the radial clearance of the rear seal ring and the diameter of the rear seal ring,and decrease the lift and efficiency of the pump However.The influence of the radial clearance of the rear seal ring is greater than the diameter of the rear seal ring.When the diameter of the back seal ring is 90mm,the core area is wider than other diameters,and the tangential velocity of the core area is larger than other diameters?4.The influence of the radial clearance and the diameter of the back seal ring on the axial force is analyzed under different flow rates and the inner diameter of the balance hole,and the axial force coefficient CF is introduced.The conclusion is as follows:under different flow rates,the relationship curve between the axial force and the radial clearance of the back seal ring is nonlinear,the radial clearance of the back seal ring increases,the axial force increases;the relationship between the axial force and the diameter of the back seal ring The curve is linear.The diameter of the rear seal ring increases and the axial force increases.When the radial clearance of the rear seal ring is small,the influence degree of the axial force is greater than the inner diameter of the balance hole.When the radial clearance of the rear seal ring is large,the influence degree of the axial force is less than the inner diameter of the balance hole.The influence degree of the diameter of the rear seal ring on the axial force is greater than the inner diameter of the balance hole.The axial force coefficient decreases with the increase of the specific area.Under the same inner diameter of the balance hole,when the diameter of the rear seal ring changes,the trend of the axial force coefficient with the change of the specific area is slightly smaller than that of the radial clearance of the rear seal ring.Under different specific area (?)the variation of axial force coefficient CF with lift coefficient?is small,which provides a reference for the calculation of similar pump axial force,and the appropriate value range of specific area (?)is 2.5~4.44. |
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