| Large-scale single-stage double suction centrifugal pumps used in open a wider scope, regardless of factories, mines, urban water supply and drainage or farmland irrigation and drainage can be used, compared with single-suction pumps, it have greater flow and better absorption performance. It can balance the axial force by Two symmetrical lmpellers. Such pump resistance cavitation performance is better. But some problems often arise in running, such as the shaft sleeve in contact with the surface, as well as end-sleeve occurred fatigue failure, between the Pump to start to open the valve of the export,the seal ring often hold axis phenomenon, and the body seal of pump ring and the seal ring of impeller were bonding together. It must increase the gap of seal ring in order to the pump to start normally, and it will reduce the volume efficiency of the pump. It will impact the economic operation of pumping station.the above-mentioned issues which the Large pumping station occur from time to time, it is disturbed the normal operation of the safety of pumping stations,and 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 necessary Through the experimental method of determination of radial force is the most accurate , but it must due to large centrifugal laboratory conditions, most of them in the use of the field testing or operation of authentication, but also need to establish a costly specialized testing equipment. This is not conducive to improving the pump but expensive. This paper presents numerical simulation of centrifugal method of radial force, the establishment of the radial force of the calculation model. Takel200S56 type pump as an example, Fluent software applications on the internal flow field of three-dimensional numerical simulation of steady-state of the single volute chamber, the double volute chamber and the composite impellers centrifugal in different flow, and given the distribution of static pressure and radial velocity of the export of impeller, and application radial force calculation model to calculate the above three types of structures in different flow of radial force. Fluent software has applications on the internal flow field of three-dimensional numerical simulation of non-steady state of the single vortex chamber pump work in 0.4Qi flow,it is obtained radial force component change with time t cycle curve, the System which is composed of the impeller and pump shaft were be vibration analysis.The main research of the radial force on centrifugal pump as following:1. The calculation mathematical model of the radial force on centrifugal pump was be established.2. In the small flow condition, the radial force on double volute pump is smaller, in the vicinity of 0.4Qi flow conditions, the radial force on double volute pump is smallest,.In the vicinity of the design flow conditions, the radial force on single volute pump is smaller. In Qi flow condition,. the radial force on single volute pump is smallest,. In big flow conditions, the radial force on the length of composite vane pump is smaller, in the vicinity of 1.2Qi flow conditions .,the radial force on the length of composite vane pump is smallest.3. The gradient which the radial force on double volute pump change with the flow is relatively small,and the area of low radial force is comparatively broad. Therefore, double volute structure most conducive to reducing the centrifugal pump radial force in the three structures,.4. In 0.4Qi flow condition, the radial force component on single volute pump change with time t cycle were similar to sine curve and cosine curve, the tracks of the vibration system is a ellipse.
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