Energy Transfer Mechanism And Flow Control In Mixed-flow Impeller Of Nuclear Coolant Pump

Mixed-flow pump is always to be the nuclear coolant pump(short for nuclear RCP)because of its characteristic with high head and large flow-rate.Energy in the pump is from impeller with rotating,so it is the key to improve the hydraulic efficiency of the pump by optimizing the way of energy delivery in the mixed-flow impeller.This paper studied the mixed-flow RCP we designed and separate the impeller from the main pump to specialize in it.The flowing characteristic around blades and blade loading regularities of distribution were analysed and explore the way of flowing decomposing in impeller.The main work and conclusion as:1.The experiment about the RCP model was carried out in closed test-bed system and compare results between experiment and the simulating calculation.We find the error rate around 3.5%.The comparison results could ensure that the calculation model and boundary conditions are right.2.This paper studied the laws of blade thickness on the direction from shroud to hub to get the influence of impeller performance,blade loading and flow field inside the impeller with different blade shape.The characteristic of blade working could be get by studying the transverse blade loading on pressure surface and suction surface.The velocity and pressure on impeller outlet surface were studied to have the energy distribution characteristics.3.The meridian velocity vector decomposed to axial and radial in mixed-flow impeller with different blade thickness and have them quantization process.Analyzing the main leading flow direction and the leading field in the mixed-flow impeller.The conclusion is: the flow near outlet is radial in the impeller and the flow in the rest position is dominated by axial direction.Fitting the three velocity curves and find that the meridian velocity equation accord with three times polynomial function in axial leading area.However,the velocity equation conform to linear polynomial function in radial leading area.4.The driving coefficient can show the promoting ability of impeller.According to compare the promoting coefficient in axial and radial,the promoting ability in axialis greater than in radial in any location of impeller.The promoting ability and the difference value is greater as approaching hub.5.The single impeller with guide vane was calculated with large eddy simulation to catch small scale eddy.This paper monitoring the pressure pulsation in guide vane flow passage and find that the blade frequency is the primary factor in pump vibration caused by pressure pulsation.The thicker blade caused the greater pulsation amplitude and it is not suitable for flowing in impeller.6.The mixed-flow impeller was Optimized for different regions with different flow characteristics.This paper took the optimization method of centrifugal impeller near the impeller outlet region with changing the blade outlet angle.We found that relatively small blade outlet angle can improve the hydraulic efficiency of the impeller.