Research On Coupling Vibration Characteristics Of Adjacent Tube Bundles Of Heat Exchange Tube Arrays Under Transverse Flow

With the increasingly severe global energy problems,human demand for renewable energy is also increasing.As a renewable clean energy,nuclear energy is being reused by more and more countries.Nuclear power plant safety problems also follow.As a steam generator,one of the three major components of nuclear power plants,its tube bundle flow-induced vibration problems will cause the structural integrity of the equipment to fail,seriously threatening the safety of nuclear power plants.For the problem of tube bundle flow-induced vibration of heat exchangers,domestic and foreign scholars have done a lot of research work and achieved fruitful results.However,due to the complexity of the tube bundle flow-induced vibration mechanism,this problem has not yet been substantially resolved.At the same time,with the increase in energy demand,the problem of the development of large scale shell and tube heat exchangers at home and abroad,the problem of vibration failure caused by the heat exchanger tube bundle flow is more urgent and needed.In this paper,for the problem of vibration caused by the flow of adjacent tube bundles in the heat exchanger tube array,a transposed square array with a pitch ratio of 1.633 is used as the research object,and a high-order computational fluid dynamics(CFD)/ computational solid mechanics(CSD)coupling algorithm,this method is used to numerically analyze the mechanism of tube bundle flow-induced vibration in a dense tube array,and to explore the coupling vibration characteristics of adjacent tube bundles and the interaction between tube bundle vibrations.The specific work and main conclusions of this article include:(1)Through the assumptions and theoretical analysis of the numerical simulation conditions,the calculation model required for the research in this paper is established.By comparing and verifying with the experimental data,the established numerical calculation model can be very good to solve the flow-induced vibration of dense tube array.(2)Based on the CFD method,combined with the moving grid idea and the linear multi-step solving method of differential equations,a high-order CFD/CSD coupling algorithm is proposed.Using this method to conduct a self-excited vibration study of a single flexible tube on a transposed square array,it was found that the frequency reflected in the tube bundle velocity response spectrum analysis includes the tube bundle natural frequency and the flow field dominant frequency,where the flow field dominant frequency is the vortex shedding frequency,So vortex shedding is an important cause of tube bundle vibration in the tube array.(3)The self-excited vibration simulation of flexible tube bundles with different natural frequencies was studied,and the relationship between natural frequency and fluid force and tube bundle vibration was discussed.It is mainly found that as the natural frequency of the tube bundle gradually approaches the dominant frequency of the flow field,the higher the natural frequency,the smaller the maximum vibration displacement of the tube bundle.However,when the natural frequency increases to the dominant frequency of the flow field,the peaks of displacement and velocity will increase sharply to a larger value.Therefore,the design of the tube bundle should pay attention to balancing the natural frequency of the tube bundle and the dominant frequency of the shell-side flow field.(4)Through the analysis of the calculation results of the simultaneous vibration of the target tube bundle and its adjacent tube bundles,it is found that in the current tube bundle arrangement structure,the addition of the adjacent vibrating tube bundles in the flow direction will reduce the vibration of the target tube bundle,and the reduction is obvious.The reduction of the setting is not obvious,so certain anti-vibration measures are required in the non-flow direction to strengthen the reduction effect.(5)When multiple adjacent tubes around the target tube bundle vibrate at the same time,this will have a certain effect on the fluid force of the target tube,especially the lift response;and the lateral flow has a dominant frequency under each operating condition,and is relatively Due to the vibration of a single flexible tube bundle,the simultaneous vibration of adjacent multiple flexible tubes will reduce the lift amplitude of the target tube.However,the enhancement of the lift coefficient spectrum does not necessarily affect the magnitude of the displacement of the tube bundle.The major difference between the dominant frequency of the flow field and the natural frequency of the tube bundle is the main reason for this situation.