| Double-suction centrifugal pumps are widely used in irrigation, urban water holding, inter-basin water transfer and other fields, is an important hydraulic machinery. It is composed of two back to back impellers impeller combination, in the same impeller diameter, its flow can be increased twice. Symmetrical double-suction pumps, axial force on both sides cancel each other out, balance is better, thanks to the open structure, you can open the pump cover pump repair parts, maintenance is very convenient. And cavitation resistance of this pump is better performance, but some failure in the run often, such as the shaft surface in contact with the sleeve and the sleeve end surface fatigue damage, etc., from the start to open the outlet valve of the pump between Axle seal ring phenomenon often occurs, the pump impeller seal ring seal ring and bonding, sealing ring gap must be increased to normal startup. The seal ring clearance volume is reduced to increase the efficiency of economic operation of pumping stations. These problems occur when running a large pump station, seriously affecting the normal operation of the security station, need to be solved fundamentally.Through the analysis found that the main reason of currently the large centrifugal pump occurrence problems of the above is the radial force of single volute pump is too large When the pump work in the non-design condition. for the rotation axis,the radial force is an alternating load, this will result in shaft vibration, and increasing the uncertainty of pump.Therefore, Study of radial force of centrifugal pump is necessaryBy analyzing the phenomenon of centrifugal rotor vibration found centrifugal pump operating conditions change will cause structural changes within the flow field, suffered the impeller to the uneven distribution of load week, so the fluid exciting force produces radial impeller, causing vibration and noise. Exciting force on the impeller the fluid force can be divided into steady state and transient forces, which the impeller rotor steady-state force on the impeller would appear eccentric, transient centrifugal force will cause the vibration of the rotor. Therefore, the study of steady state and transient impeller force is necessary. In this paper, numerical simulation of steady state and transient centrifugal force of the method, a calculation of the impeller the fluid exciting force model. 1200S56 pump to an example, Fluent, respectively, under different flow centrifugal flow field within the three-dimensional numerical simulation of steady state, gives the suction chamber, the impeller and the static water pressure chamber and the distribution of velocity, Of fluid on the impeller forces calculation model to calculate the steady-state forces in different conditions. and the internal flow field of pump flow in 0.6Q under the unsteady three-dimensional numerical simulation of transient effects obtained Force component, with the time cycle curve. The main research results in this paper are as follows:1. In conveying water, double suction pump impeller from imported to export, pressure increases experienced first decreases in the process, the same radius, leaf high pressure is working on the back pressure; Double suction pump impeller from import to export, speed decreasing gradually, the same radius, the speed from leaves in the back to leaf face increased gradually. Impeller velocity field and pressure field have mild distribution is uneven phenomenon, this and using half spiral water-obsorbing room double suction pump about special structure.2. In different conditions steady-state force calculation values change trend is basically the same with experimental data, centrifugal pump deviation design conditions steady-state forces when will increase significantly; In 0.6Q flow, transient radial force component of periodic changes with time for approximate cosine curve respectively, sine curve.3. To ANSYS Workbench double suction pump impeller rotor of the modal analysis, and to get its 1 ~ 6 modes of vibration frequency.
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