换热器壳程分布式脉动流诱导多排弹性管束振动研究

The flow-induced vibration (FIV) in elastic tube bundle heat exchangers plays positive factor in heat transfer enhancement, while it is negative in the fatigue life of elastic tube bundles. The research in this project aims to balance the paradox of flow-induced vibration both in the heat transfer enhancement and the fatigue life of elastic tube bundles. Based on analyzing the mechanism of heat transfer enhancement via vibration, the influence of vibration parameters on the heat transfer of elastic tube bundles in heat exchanger would be investigated. The evaluating model for fatigue life prediction in condition of elastic tube bundle vibrating would be created. To research the tube bundle structure, vibration modes, stress distribution characteristics, and its fatigue life. To improve the tube bundle structure and its support. With the above research, the project tries to definition the critical vibration parameters for elastic tube bundles both benefic in the tube heat transfer enhancement and tube fatigue life. The project would concern on the design of the distributed pulsating flow generate device, and to determine pulsating flow frequency and excitation direction, aims to obtain consistent distributed pulsating flow with certain pulsating intensity and frequency. The pulsating flow would be used to induce and control the multi-elastic tube bundles uniform vibration in heat exchangers. Finally, the coupling interaction of heat exchanger shell-side fluid flow and pulsating flow would be studied, and the vibration, heat transfer enhancement and fatigue life of elastic tube bundles would be evaluated. The coordinated matching of the vibration characteristics, the heat transfer enhancement and the fatigue life of the elastic tube bundles could be obtained. The research could develop the proprietary heat transfer technology and highly efficient heat exchanger. The research conclusion in this project has a wide application prospect in heat exchange field.

换热器内流体诱导弹性管束振动是强化管束传热的积极因素，同时也是影响管束使用寿命的不利因素。针对弹性管束振动强化传热与疲劳寿命相悖的问题，本申请结合振动强化传热机理，研究换热器内弹性管束振动参数对其强化传热的影响规律；建立弹性管束疲劳寿命评价模型，研究管束结构、振型、应力分布及疲劳寿命，改进弹性管束结构及支撑方式，寻求兼顾弹性管束强化传热与使用寿命的振动参数范围；设计分布式脉动流发生装置，确定脉动流频率及激励方向，获得一定强度和频率的分布式脉动流，诱发和控制多排弹性管束均匀振动；考虑换热器壳程流场与脉动流耦合作用，评价管束振动、强化传热与使用寿命，实现管束振动-强化传热-疲劳寿命的协同匹配，发展具有自主知识产权的传热技术和高效换热器。该项目的研究成果在电力、冶金、石油化工等需要热量交换领域具有十分广阔的应用前景。

在管壳式换热器中流体绕流换热管束时诱导管束振动，导致换热管束疲劳破坏。弹性管束换热器是利用流体诱导弹性管束振动并实现无源振动强化换热，提高换热效率。但是，换热器内流体诱导弹性管束振动是强化管束换热的积极因素，也是导致管束疲劳破坏的不利因素。本项目针对弹性管束振动强化传热与疲劳寿命相悖的问题，提出利用分布式脉动流，激励并控制弹性管束实现预期振动，在满足弹性管束强化换热的同时兼顾管束的疲劳寿命。项目的研究结果为弹性换热管束振动主动控制的高效换热器设计提供了理论依据，具有广阔的应用前景。 .通过对比分析刚性管束和弹性管束壳程对流换热，揭示了流体流动参数及结构参数对对流换热的影响规律，拟合得到了多排刚性管束换热经验关系式。采用双向流固耦合顺序求解法，数值计算了壳程流体诱导弹性管束振动强化换热，拟合得到含流体雷诺数和振动雷诺数共同作用的流体诱导弹性管束振动强化换热经验关系式。.对弹性管束进行了多轴应力疲劳分析，提出了基于Von Mises应力准则的弹性管束振动疲劳强度判定图，确定了弹性管束既满足疲劳强度又实现强化换热的振动参数范围。.设计了弹性管束换热器内壳程分布式脉动流发生装置及换热器。以各分支形成脉动流频率和强度的均匀性为目标，基于流体绕流分析，选择了合适的扰流体，设计了分支管结构。建立了壳程流场与分布式脉动流体耦合诱导弹性管束振动响应的数学模型，进行了弹性管束在壳程流场和分布式脉动流耦合诱导下的振动分析。.搭建了流体诱导弹性管束振动实验测试平台，实验研究了脉动流与壳程流场耦合作用下弹性管束振动响应。数值模拟和实验结果均表明，分布式脉动流发生装置基本实现了换热器内各排弹性管束均匀振动的有效激发和控制。.数值分析了分布式脉动流场、耦合流场以及平稳流场中弹性管束的面均换热系数。分布式脉动流可以保证弹性管束疲劳强度并实现各排管束换热系数均匀，提高换热器整体换热能力。