Experimental And Numerical Simulation Of Fretting Wear Of Heat Transfer Tube Of Nuclear Main Pump External Heat Exchanger

The CAP1400 reactor coolant pump external heat exchanger is mainly used to cool the primary side water of the reactor coolant coolant pump motor of the nuclear power plant.The design life of the nuclear main pump external heat exchanger is 60 years.In order to ensure that the operation during its lifetime can meet the requirements of ASME specification analysis and design,it is necessary to consider the amount of wall thinning caused by the heat transfer tube during the 60-year operation.On the other hand,in order to ensure the heat exchange requirements of the external heat exchanger of the main pump,it is not allowed to set an excessively conservative margin,and it is necessary to conduct in-depth research and analysis on various parameters including the amount of wear.Therefore,research on heat exchanger tube heat exchanger wear is carried out.Through the organic combination of analysis and experiment,revealing the fretting wear process,it can more accurately and comprehensively evaluate the wall thickness of the heat transfer tube,providing strong support for the design.At the same time,it is of great significance to predict the life of heat transfer tubes and the safe operation of nuclear power plants.In order to design the heat transfer tube/support plate support structure with long service life,this paper developed a dynamic contact numerical model for simulating the vibrational collision behavior of heat exchangers and carried out experimental verification.Based on the proposed high-efficiency dynamic contact model,the contact force between the heat transfer tube and the support plate is predicted,and the wear of the heat transfer tube under a certain load is further studied.For the problem of vibration collision simulation of heat transfer tube,the heat transfer tube is simulated as Euler-Bernoulli beam.By introducing parameter variables,the heat transfer tube dynamic contact problem is transformed into a standard linear complementary problem,which avoids the iterative process of the traditional dynamic contact algorithm and ensures the convergence of the calculation.The effectiveness of the proposed numerical model for dynamic contact of heat transfer tubes is verified by experiments.The effects of different contact stiffness,different support plate thicknesses and different support plate aperture sizes on the vibration behavior of the heat transfer tube and the collision force between the heat transfer tube and the support plate were studied by numerical simulation.The experimental study on the wear of the heat transfer tube is carried out.The simulated heat transfer tube is excited by the vibration exciter.Based on the proposed numerical model of the dynamic contact of the heat transfer tube,the collision contact force between the heat transfer tube and the support plate is obtained.The vibration behavior of the heat transfer tube under different conditions such as boundary hinge-fixation and air-water is studied under certain contact force conditions.Based on this,a support plate is further installed to study the collision and wear behavior of the heat transfer tube and the support plate.Change the different collision cycles and study the relationship between different collision cycles and heat transfer tube wear behavior.Study the wear scars and analyze the changes in wear behavior.Master the preliminary wear rules and provide some experimental basis for subsequent research.