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Wang X.-L.,Jiangsu University | Yuan S.-Q.,Jiangsu University | Zhu R.-S.,Jiangsu University | Fu Q.,Jiangsu University | Yu Z.-J.,Jiangsu Zhenhua Pump Manufacturing Co.
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2012

For studying transient hydraulic characteristics and internal flow mechanism in a centrifugal pump from design conditions to non-design transition, a three-dimensional modeling for a centrifugal pump internal flow was done with three-dimensional software pro/E. Based on Reynolds-averaged Navier-Stokes equations with RNGk-ε turbulence model and SIMPLEC algorithm, using a full-cavitation model and considering effects of cavitations when gas did not dissolve in water, using the computational fluid dynamics software CFX, the numerical simulation calculation for transient flow characteristics under variable operating conditions in whole flow passage of a centrifugal pump was conducted. The cavitation characteristics of a centrifugal pump under the condition of inlet pressure continuously declining were analyzed with numerical simulation, and the results were compared with the experimental ones. It was shown that the numerical simulation results and the experimental ones have the same trend. The flow field analysis showed that under the condition of variable flow transition, the pressure around the impeller does not significantly increase, but the amplitude of the pressure increases with increase in flow; in the transition to large-volume, the increase in flow has little effect on the blade transient load, but in the transition to the low flow, the presence of secondary return and other factors have a great effect on the blade transient load; in the transition process from design conditions to cavitation conditions, at a critical NPSH, affected by bubble phases, the blade transient load varies greatly, especially, in the inlet, it varies more; the pressure and its amplitude have sharp declines; the radial force acting on the impeller also has sharp increases. Source


Wang X.-L.,Jiangsu University | Yuan S.-Q.,Jiangsu University | Zhu R.-S.,Jiangsu University | Fu Q.,Jiangsu University | Wang J.-G.,Jiangsu Zhenhua Pump Manufacturing Co.
Yuanzineng Kexue Jishu/Atomic Energy Science and Technology | Year: 2014

In order to decrease pressure fluctuation of the reactor coolant pump under different conditions, three different inlet diameters of short blade of the reactor coolant pump were compared using numerical simulation, and the results show that the change of flow or inlet diameter of short blade does not change the dominant frequency of impeller. The high frequency of the suction side of blade gradually decreases and the high frequency of the pressure face gradually increases with the increase of inlet diameter of short blade. The pressure fluctuation amplitude of different inlet diameters of short blade with small flow is large. The wave energy of each monitoring point in the low frequency region and the high frequency region on the suction side of blade is significantly larger than that of the pressure face in the design condition. The band width of the low frequency region and wave energy of the high frequency region of monitoring points near the suction side of blade significantly increase at large flow fluctuation. The fluctuation amplitude of monitoring points near the pressure face of the blade has a large increase. The pulsation amplitude of each monitoring point near the suction side of the short blade is significantly higher than that of the long blade. The comprehensive analysis shows that when the inlet diameter of the short blade is 0.72D2, the pressure fluctuation in a variety of conditions reaches minimum. Source


Wang X.-L.,Jiangsu University | Yuan S.-Q.,Jiangsu University | Zhu R.-S.,Jiangsu University | Fu Q.,Jiangsu University | Wang J.-G.,Jiangsu Zhenhua Pump Manufacturing Co.
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2014

To study the effect of number of blades and guide vanes on a reactor coolant pump's radial force under variable flow transition conditions, the computational fluid dynamics software CFX was applied in the numerical simulation and test for the radial force variation law with number of blades or guide vanes changed. Compared the numerical simulation results with the experimental ones, both of them were within the error control range. The results showed that with flow rate increasing, the radial force of the reactor coolant pump impeller increases with increase in number of blades, and reaches the maximum value with the blade number of 7, the periodicity of the radial force tends to regularity, the radial force balance tends to the optimum working condition; with flow rate decreasing, the position of the impeller radial force offsets and rotates regularly in its rotating cycle, and the variation gradients of offset and rotation are different; the variation gradients of the impeller radial force offset and rotation are obviously greater than those corresponding to a larger flow increasing. Through the comprehensive comparison, it was shown that when the number of blades is five and the guide vanes is 11, the radial force on the impeller is the minimum. ©, 2014, Chinese Vibration Engineering Society. All right reserved. Source


Wang X.-L.,Jiangsu University | Yuan S.-Q.,Jiangsu University | Zhu R.-S.,Jiangsu University | Fu Q.,Jiangsu University | Yu Z.-J.,Jiangsu Zhenhua Pump Manufacturing Co.
Yuanzineng Kexue Jishu/Atomic Energy Science and Technology | Year: 2013

For the study on the transient hydraulic characteristics and internal flow mechanism of the nuclear reactor coolant pump in the transient process from design operation conditions to off-design conditions, the variable flow transient characteristics of centrifugal pump impeller passageway were simulated by using CFX software. The results show that during the variable flow transition, the distribution of pressure pulsation of the nuclear reactor coolant pump along the circumference direction is non-uniform. The pressure pulsation trends to rise gradually to reach the maximum value and then fall, basically following a sine-shape changing law. The times of transient pressure fluctuation change are equal to the times of rotor-stator interference between the vane and the guide vane. The closer monitoring point to the intersection surface between the vane and the guide blade is, the greater the pressure fluctuation is. Because of the attack angle, the speed of the impeller passageway first falls and then rises. The guide vane not only transfers the kinetic energy to pressure energy, but also effectively reduces the pressure pulsation amplitude. During the transition to small flow, flow reducing causes the secondary backflow to occur near the outlet of impeller and in turn leads the amplitude of flow velocity variation in the flow channel of impeller to increase with flow decrease. Source


Wang X.,Jiangsu University | Zhu R.,Jiangsu University | Su B.,Jiangsu University | Yu Z.,Jiangsu Zhenhua Pump Manufacturing Co.
Nongye Jixie Xuebao/Transactions of the Chinese Society of Agricultural Machinery | Year: 2012

The optimization design of vortex pump impeller parameter was done by using the orthogonal design method. Orthogonal scheme of five factors and two levels was designed, and the influence of geometrical parameters on the characteristics was studied. Reynolds averaged Navier-Stokes method was adopted to simulate every set of parameters obtained by the orthogonal design method. Optimal scheme of the characteristics was found by analyzing the contrast of performance curves. The influence orders of geometrical parameters to the characteristics were obtained with range analysis. The optimization parameter combination was obtained with comprehensive balance analysis and comparison to the data result. Meanwhile, the optimized design scheme was determined, and corresponding test was carried out. It demonstrated that the experimental purpose was reached, the design method was reasonable, and it had the property of both high efficiency and non-overload. Source

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