Flow Induced Vibration Mechanism Of Dense Flexible Tube Bundle

Fluid-induced vibration problems exist widely in aerospace,nuclear power,deep-sea mining,petrochemical and other fields.For example,there are oil heat exchanger for space rockets,aircraft engine oil pipelines,nuclear reactor fuel rods,steam generators,submarine oil pipelines and other tube bundle structure with vibration and wing flutter.The rapid development of various industries puts higher requirements on stability and reliability.In this paper,the problem of vibration is investigated for two heat exchangers of different type but similar in structure,that is compressor heat exchangers and raw water heaters.Compressor shell-and-tube heat exchanger,also known as tube heat exchanger,is a special heat exchange device for compressors in the chemical and petrochemical process.It is used to achieve direct heat exchange between cold and hot fluids to reduce the inlet temperature of the next stage and improve compression efficiency.Raw water heaters are auxiliary equipment for large machinery.Destruction of heat exchangers will lead to overall equipment downtime,causing incalculable damage to production and economic benefits.Therefore,it is very important to understand the vibration mechanism of the heat exchanger and to ensure the structural reliability and working performance of the heat exchanger.The core components of the heat exchanger are a large number of densely packed heat exchange tubes subjected to periodic pulsating pressures of the transverse fluid,which is a fluid-induced vibration.Due to the complex fluid flow in the heat exchanger,the fluid-structure interaction involves dynamics,nonlinearity,fluid mechanics,and other disciplinary.To this date there are still many uncertainties in the mechanism and criteria of fluid-induced vibration.Therefore,it is the focus of this paper to study the vibration phenomena of heat exchange tube bundles,the mechanism of fluid induced vibration,and the vortex-induced vibration of heat exchange tubes.In this study,the effect of tube-fluid interaction is investigated on the transverse vibration of heat exchange tube bundles.Based on the beam vibration model,a MATLAB program was developed to verify the feasibility of the additional mass method to the fluid in the tube in the heat exchanger.The ANSYS CFX software is adopted for numerical simulation of the field of viscous incompressible fluid.The fluidal excitation is obtained on the heat exchange tube through the Fourier transformation to clarify the mechanism of vibration of the tube bundle.The vibration force is loaded on the corresponding surface of the heat exchange tube to disturb the tube in the form of cyclic loading.A measure for mitigating vibration amplitude is proposed based on the vibration mechanism.The vortex-induced vibration of the heat transfer tubes in the flow field is simulated with a two-way fluid-solid coupling analysis to provide a basis for avoiding resonance.