| As the equipment of fluid transfer and heat transfer,the heat exchanger is popular in industrial production and occupies a high proportion.Heat transfer performance and service life are important factors that directly affect heat transfer efficiency and safe operation.The principle of the elastic tube bundle heat exchanger is to enhance heat transfer by fluid-induced bundle vibration.However,vibration fatigue failure is always a problem in the effective operation of equipment.Therefore,it is very important to induce and excite bundle vibration in a reasonable way to realize the safe operation of heat exchanger.In this paper,the vibration response of a single row of planar elastic tube bundle induced by fluid is analyzed by means of simulation calculation and experiment.The heat transfer performance of tube bundle under the condition of pulsating flow-induced tube bundle vibration was studied.The research results will provide some theoretical guidance for the manufacture and safe use of planar elastic tube bundle.In this paper,the main research contents are as follows:(1)The simulation analysis model of flow characteristics around pulsating components with different structure and shape was established through ANSYS Workbench.The pulsating flow intensity generated by pulsating components was compared and analyzed.The pulsating flow characteristics of equilateral triangular column with different characteristic dimensions were analyzed.The results show that the comprehensive performance of the triangular column is better than that of the cylinder and the square column.The pulsating flow frequency generated by the equilateral triangular column is different in different structure sizes.(2)Based on the finite element method,the simulation model of vibration of planar elastic tube bundle induced by fluid was established.The intrinsic characteristics of the tube bundle with or without liquid filling were analyzed.The vibration response of the tube bundle induced by fluid with or without pulsating flow in the tube was analyzed.The results show that the vibration characteristics of the planar elastic bundle are the vibration outside the plane and the vibration inside the plane The natural frequency of the tube bundle is less when the tube is filled with fluid than when it is not The amplitude of the free end of the tube bundle increases correspondingly with the increase of the flow rate in the tube.The amplitude increment of the small free end of the tube bundle is larger than that of the large free end,indicating that the vibration of the small free end is more easily affected by the flow rate in the tube.Under the action of pulsating flow in the tube,the vibration frequency of free end of the tube bundle basically does not change with the increase of velocity,but the amplitude increases.(3)The experimental platform of fluid-induced vibration of elastic tube bundle was constructed.The vibration displacement and frequency of the small free end of the tube bundle along with the flow velocity in the tube were analyzed in the case of fluid with or without pulsating components.The results show that when the inlet velocity in the tube was 0.1m/s-0.6m/s,the amplitude of the free end of the tube bundle increases with the increase of the flow rate.Under the condition of the same flow rate in the tube,the amplitude of the small free end of the tube bundle induced by the pulsation flow increases slightly.(4)The simulation model of vibration intensification heat transfer of the planar elastic tube bundle induced by pulsating flow in tube is established.The influence of pulsating flow on the heat transfer coefficient of tube bundle wall is analyzed.The heat transfer performance of elastic tube bundle is evaluated by using the Performance Evaluation Criteria,PEC.The results show that under pulsating flow excitation,the PEC value is greater than 1 when the inlet velocity of the tube bundle is less than or equal to 0.3m/s,and the comprehensive heat transfer performance of the bundle is better. |
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