| As an important clean energy form nowadays,nuclear power is indispensable for ensuring the safe operation of nuclear power plants.The third-generation nuclear power units are commonly used today to ensure high reliable operation.Nuclear Reactor Coolant Pump(RCP)is the only rotating part of nuclear power plant reactor primary circuit,also called RCP.Its main function is to transport the coolant circulating in the primary circuit.RCP rotor component needs long-term high-reliability operation under the conditions of high temperature,high pressure and high rotating speed,which is related to the safe operation of the entire nuclear power system.Dynamic analysis of RCP rotor components is of crucial importance.In this paper,CAP1400 nuclear canned motor pump is taken as the research object,and the rotor is included in the hydraulic components to explore dynamic characteristics of the impeller and rotor components.Firstly,the impeller was simplified into a disk model,and the numerical simulations are verified by experiments.On the basis of the reduced-scale impeller model,effects of boundary conditions and high temperature and pressure environment on the impeller mode characteristics were studied.Firstly,the numerical simulations were verified by experiments;then RCP rotor component was simplified and modeled,and the wet mode analysis was carried out to explore the influences of pre-stress and high temperature and pressure environment on its mode;the flow fields of the full-scale model were simulated to obtain the frequency domain characteristics of pressure pulsation.Dangerous conditions at which impeller may resonate were found,and the fluid damping ratio and dynamic stress were determined under the real constraint conditions.Finally,the rotor dynamics analysis was performed on the rotor component to find its critical speed and analyze the imbalance response for a specific situation.It is found that:(1)the simplified disk wet mode frequency is reduced by about 25% compared with the dry mode frequency;the impeller mode frequency follows the same law,gradually decreases with the increase of the dive depth,and increases with the increase of the radial distance;the impeller natural frequency increases in high temperature and pressure water environment compared with that in the normal temperature and pressure.(2)A large inertia flywheel is added during the wet mode analysis of the whole rotor component.The results show that it has an obvious influence on the mass matrix of the structure.In contrast,the influence of the water added mass and damping is weakened;the gravity field slightly decreases rotor component mode frequency,and the rotating centrifugal force does not bring about stress stiffening effect of the rotor component;the fluid force increases the damping effect of the system,so that the rotor component natural frequency is reduced;the influence of temperature and pressure on the structural mode is independent of Nodal diameter(Nd).(3)The uneven flow leads to obvious rotating frequency excitation at blade leading edge.The rotor-stator interaction results in apparent 13 times rotating frequency excitation at blade trailing edge.The 1 Nd 1 mode corresponds to the most likely resonance mode.The maximum Von Mises stress is 7.96 MPa according to the harmonic response analysis,which appears at the blade leading edge root;the maximum deformation is 3.06?m,which appears at the mid-span of the blade trailing edge.(4)The rotor component first-order mode is a double-cone micro-swing,which has little influence on the mode;the second-order mode is a "U"-shaped bending vibration,which has strong influence on the mode;the first critical speed is 1099.21 rpm,which is judged to be a flexible rotor.When the unbalanced force is applied on the top of the upper flywheel,unbalanced response peak of the second-order critical speed position is 64.49 ?m.This unbalanced response is within the warning value and can be considered to meet the safety requirements for the rotor components vibration. |
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