Analysis Of Fluid-structure Interaction Characteristics Of Heat Exchange Tube Bundles

With the increasing shortage of natural resources,energy efficient and sustainable development strategies have increasingly become the goal pursued by various fields.As an important energy exchange equipment in industrial production,the improvement of heat exchange efficiency of heat exchangers has led to the development of equipment towards compactness and large-scale,which will inevitably lead to the complexity of the flow field in the heat exchanger and the more obvious phenomenon of fluid induced vibration.Therefore,studying the vibration mechanism of heat exchange tube bundles is of great significance for preventing tube bundle damage and improving heat exchange efficiency.This paper adopts a bidirectional fluid-solid coupling simulation method,in which the finite volume method is used for the fluid domain,and the turbulence model is Realizable k-ε,The solid domain is calculated using the finite volume method,and the numerical simulation results are compared with experiments to verify the feasibility of the numerical simulation method.Using this numerical simulation method 3×3 The flow field characteristics of a square tube bundle were analyzed.The results showed that under the same pitch diameter ratio and different tube bundle positions,the first row of intermediate tubes suffered the greatest resistance,and the second row of intermediate tubes suffered the greatest lift.The analysis of tube bundles at the same location with different pitch diameter ratios shows that with the increase of pitch diameter ratio,the lift and resistance of the tube bundle have little change under the pitch diameter ratio.When the pitch diameter ratio increases to 1.5,the lift and resistance have a significant decrease.By analyzing the flow field under different pitch diameter ratios,it can be seen from the velocity vector diagram that when the pitch diameter ratio is small,it is difficult to form a complete vortex shedding phenomenon between the tube banks,and the tube bundle vibration is mainly caused by turbulent buffeting phenomenon;With the increase of the pitch diameter ratio,the vortex shedding phenomenon gradually becomes evident.Based on the analysis of the bidirectional fluid solid coupling structural field,when the pitch diameter ratio is small,the deformation of the first row of tube bundles is the largest.With the increase of the pitch diameter ratio,the maximum deformation occurs in the last row of tube bundles.Monitor the movement trajectory of the tube bundle,and the tube bundle moves in an 8-shape shape with an average path at different positions and different pitch diameter ratios.The vibration response analysis of the heat exchange tube used in this paper under multi-point excitation is conducted.Firstly,the modal simulation of the heat exchange tube is performed.The results show that the wet mode frequency result is 20% lower than the dry mode frequency result,and the vibration mode results obtained by the two methods are the same in the low order mode,while the vibration mode difference is large in the high order mode.The flow force obtained from the flow field is loaded onto each point of the heat exchange tube,and the analysis shows that the vibration deformation of the tube bundle is the largest at the same phase of each point.Research on the presence or absence of fluid in the tube and the impact of tube side flow velocity on tube bundle vibration has shown that when the tube side flow velocity is low,it has a inhibitory effect on heat exchange tube vibration.When the tube side flow velocity is high,it will exacerbate heat exchange tube vibration.Overall,the direct impact of tube side fluid on tube bundle vibration is less than that of shell side fluid.