Research On Fluid Structure Interaction Characteristics Of The Variable Diameter Pipe Under Vibration Condition

The fluid structure interaction(FSI)problem has always been one of the focuses to the numerous scholars over the years.Researches paid more attention to the effects of FSI on the safety and reliability of equipments,and achieved many beneficial results.These provide basis and guidance for the reasonable design of structure.Even so,the laws of flow field under effect of FSI are more noticeable for the hydrocyclone.With the development of FSI theory and numerical calculation method,it is of great importance to improve the stability and reliability of the hydrocyclone via deeply study change laws of the flow field and dynamic response characteristics of the structure under FSI effect with the help of advanced numerical methods.The two-way FSI model of hydrocyclone with variable diameter pipes is presented in this paper,and the related numerical simulation and experimental research is also carried out.The hydrocyclone with a typical variable diameter pipe structure is selected as the research object,and the interaction of the structure and the fluid is considered on the basis of the hypothesis of small deformation.The Reynolds stress turbulence model is chose for the calculation of fluid model.Based on the finite volume method,the discrete forms of governing equations for space domain and time domain are proposed.The method of ALE is adopted to realize the correct description of the fluid moving grids.The calculation system of turbulence governing equations is established by combining second order accuracy calculation format and non-equilibrium wall method in fluid domain.The Newmark method is used to solve the dynamic equation of variable diameter pipe structure in solid domain using finite element theory,and the transfer equation of physical quantities in coupling interface is propsed.Based on the alternating iterative coupling solving method,the two-way FSI calculation model of hydrocyclone with variable diameter pipe is established.Using the established fluid-structure interaction model,the flow field numerical simulation of variable diameter pipes is studied by means of the organic glass material with variable diameter pipe bearing no external force and the stainless steel material with variable diameter pipe bearing periodic force excitation vibration under different conditions.The difference and distribution characteristics of coupling flow field are obtained between the field of FSI and no FSI after analyzing the flow field comparing with uncoupled conditions.LDV testing technology is applied to analyze the coupling flow field in the experiments.The numerical results and the measured results showed that there exist an obviously corresponding relationship and similar changing trend between them,which proved the reliability of FSI model.The dynamic characteristic of the above two kinds of material under the FSI condition is discussed,and the modal analysis of variable diameter pipe structure is carried on via the FSI theory,which obtained the vibration characteristics of structure.After compared analysis the numerical results and the measured results,an obviously corresponding relationship and similar changing trend between their vibration characteristics is developed.The time history responses of the coupling interface is obtained.The trend of the experiment and numerical simulation is consistent.The rationality of the FSI model is verified from the aspects of structural movement.The above analysis shows that the two-way FSI calculation model of hydrocyclone with variable diameter pipe is reasonable.The influence of coupling effect on flow field cannot be ignored.The interaction of fluid and structure not only changes the flow field distribution,but also changes the movement characteristics of the structure,thus accelerating the kinetic energy attenuation of the fluid.These are important influencing factors that should be considered in the design and application of hydrocyclone.