Research On Fretting Wear And Experimental Of Heat Transfer Tube Under The Fluid Induced Vibration

Heat exchanger that is the key equipment to maintain the primary coolant loop and the secondary circuit in nuclear power plant has been the focus of research on safety operation because it has a major impact on nuclear power plant. The fluid induced vibration will be occur when the heat transfer tube under the influence of the shell side fluid and tube side fluid in the heat exchanger, which will lead to heat transfer tube impact the support plant. The heat transfer tube would be damaged while the collision was serious badly because the thickness of the tube is 1~ 1.5mm. So it has theoretical and engineering significance to research the fretting wear and life prediction of the heat transfer tube.The random exciting force of the heat transfer tube under the fluid induced vibration was analyzed based on the fluid dynamics and vibration mechanics theories, and the vibration characteristic of the heat transfer tube was analyzed based on the numerical simulation method. Then, the correctness of life prediction of heat transfer tube was verified by using the method of combination theoretical with experimental. To solve the above problems, the following parts were mainly studied.1. The external factors what lead to vibration of the heat transfer tube in the heat exchanger were analyzed, and the law of the tube in vibration was observed. The vibration characteristic of the heat transfer tube under the influence of both shell side and tube side fluid was analyzed in the cross flow heat exchanger, then the random exciting force and vibration frequency of the heat transfer tube were analyzed and calculated.2. The former sixth-order natural frequency and model shape were obtained by using the method of numerical simulation, and the dates of displacement, velocity and acceleration changing over time of the middle node were obtained by analyzing the vibration characteristics of the tube that fixed at both ends and under the alternate load. And the impact force and vibration frequency were calculated according to the vibration characteristics of the heat transfer tube.3. Fretting wear between the heat transfer tubes and the support plates was studied, the fretting classification and movement patterns were analyzed and the related factors were introduced. Based on the existing information and improved the method of calculations, the life of fretting wear was divided into three stages: fretting, crack initiation and crack propagation. The overall cycle life of the fretting wear could be obtained by analyzing and calculating the life of the three stages.4. The natural frequency of the heat transfer tube was studied by experiment and the change of natural frequency was obtained between the straight tube without water and with water inside the tube, and the dates between the straight without water and the numeral simulation were compared. The results show that the results of experimental and numerical simulation had little difference. The natural frequency of the U-shaped heat transfer tube with different fixed positions and number and tightness were studied, the results show that the natural frequency of the U-shaped heat transfer tube increased with the increase of the fixing tightness and the fixed number, and had a relationship with the fixed position.