Study On Fluid Elastic Instability Of Tube Arrays In Heat Exchangers

Heat exchanger is the most widely used heat equipment in chemical production process, the safety of equipment has a great influence on production operation, but there are many case of failure for equipment resulted by vibrations. Therefore, the vibration of tube arrays in heat exchanger induced by fluid is always the key research for experts and scholars at home and abroad. And the fluid elastic instability is one of the important reasons for vibration of tube arrays in heat exchanger.A finite element model for calculation of the fluid elastic instability is proposed in this paper, the generation process of fluid elastic instability of tube arrays is simulated by fluid-structure coupling method, it is concluded that the drastic change of flow field is the important reason of vibration on tube arrays, and the critical velocity is calculated. According to the domestic and foreign research, an installation is designed and set up for research of vibration induced by fluid, and the generation process and discipline of fluid elastic instability of tube arrays is researched by experiment. Based on the comparison of result which calculated by finite element method and that by experiment, it is shown that the model is in good agreement with the experimental results, and the correct of the models is proved. Meanwhile, the results calculated by TEMA guidelines is evaluated, it is concluded that the TEMA guidelines are on the conservative side.The influence of natural frequency on the critical velocity is researched using finite element model, and it is shown that the change of natural frequency will affect the track of vibration, which has relation with the arrangement and the pitch to diameter ratio. When there has low frequency tube in arrays, the critical velocity will be reduced.Finally the rule of phase change when the fluid elastic vibration occurred is discussed preliminary, it is found that there is phase lag between tubes, and it has relation with the arrangement and the pitch to diameter ratio.Some new methods are proposed for study of fluid elastic instability of tube arrays in heat exchanger and the reference for formulation of standards is provided from this paper.