| The butterfly valves are widely used in different kinds of pipe systems in which fluid are transported,because they are famous for the unique structures and outstanding working performance,butterfly valve is a kind of valve which has a lot of advantages,such as simple structures,easy to operate,long service life.The research for the performance of the butterfly valve is usually relied on traditional valve characteristic tests,but the tests not only need human resources,but also require long testing cycles and huge funding,as well as some other uncontrollable factors.The computational fluid dynamics and finite element methods have developed rapidly in recent years,which can provide a totally new ideas and ways for the research and design of the butterfly valves.Through numerical simulation and finite element simulation,we can observe the flow state of the butterfly valve's flow field or the stress distribution of the sealing contact surfaces comprehensively,thus,the engineers could master some better methods to improve and optimize the qualities of the valve products.This paper takes a new butterfly valve product as the research object combined with CFD theory and finite element method,conducts the research of the flow characteristics and sealing characteristics of the butterfly valve by means of CFD and CAE software.The main jobs of this thesis are listed as follows:(1)Established the flow channel finite element model of the butterfly valve,performed the numerical simulation of the steady flow of butterfly valve under different opening degrees through Fluent software,obtained the flow visualization results of the flow fields,including the pressure distribution,the velocity distribution and the streamline distribution of the whole flow fields and the butterfly plate,and finally analyzed the flow field structure features and the flow laws;(2)Obtained the flow characteristics and flow resistance characteristics of the butterfly valve,and compared with empirical values at the same time,verified the rationality of the flow channel finite element model and the feasibility of numerical simulation which is applied in butterfly valves' flow field simulation,put forward some suggestions about how to avoid the swirls,vibrations and noises in the practical works;(3)Conducted the numerical simulation of the butterfly valve's flow under gas-liquid two-phase flow conditions,obtained the flow field structure feature and the flow patterns of the two-phase flow field,revealed the effects of gas phase distribution rate on flow performance of butterfly valve;(4)Combined with evaluation model of the sealing performance,calculated the characteristic parameters about the sealing performance,established the finite element model of main sealing contact structure of butterfly valve,performed the nonlinear finite element simulation of the valve's contact sealing performance under different flow loads and flow directions based on the ANSYS Workbench software,obtained the contact pressure distribution,frictional stress distribution and deformation distribution of the sealing surface;(5)Conducted the data post-processing of the simulation results,mainly studied the change rule of the contact pressure,frictional stress and deformation of the oblique cone surface under different flow loads and flow directions,performed the assessment and prediction of the sealing performance of the butterfly valve,put forward some useful advice about the improvement of the sealing performance according to the simulation results and the engineering practice;(6)Optimized the structural parameters of butterfly valve sealing parts based on the response surface analysis methods,and conducted the finite element simulation of the improved sealing model,compared with the simulation results before optimization,verified that the optimization results can improve sealing performance effectively and reduce volume of the sealing part and material consumption,it is of vital importance for the enterprise to reduce costs. |
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