| Thin-walled structural cylinder such as cooling tower always produces periodic vibration due to the aerodynamic effects in the flow field. Wind-induced vibration also has counterproductive effect on circular cylinder, thus affecting the distribution characteristics of the wind load. Interaction between fluid and thin-walled structural cylinder belonging to fluid-solid coupling problems involving with complex three-dimensional flow and solid vibration, for solving this problem, dynamic mesh method of FLUENT software was used to simulate the three-dimensional circular cylinder flow in order to verify the validation of numerical simulation methods. Then the same method was conducted to study the static and dynamic pressure load distribution of cooling tower under stationary and forced vibration condition, thus providing a basis for the design of modern large lanky hyperbolic cooling tower.This paper firstly studied the force distribution of a cylinder in the three-dimensional flow field by using different turbulence model such as Realizable κ-ε turbulence model, by comparing the drag coefficient and Strouhal number to verify the accuracy of the calculation model. Followed by the addition of vibration equations based on the elastic cylinder to study the influence of forced vibration on fluid forces, the results showed that the added forced vibration increased the size of fluid force and amplitude of oscillation, thereby increasing the pressure coefficient of the cylinder surface.This thesis focused on the research of force and vibration of a large lanky cooling tower in the natural wind field. Geometry was established by SolidWorks and mesh division was completed in ICEM. The paper firstly simulated the force of cooling tower under static pressure and compared the research data with the specification to verify the validation of numerical simulation methods. By analyzing vibration mode of the cooling tower under the influence of wind load and then mainly extracted the first main mode of transverse vibration which had the greatest impact on the wind vibration, and simplified the mode to a single degree of freedom damped forced vibration, Thus adding amplitude and frequency of the tower into the process of numerical simulation by using the UDF dynamic mesh. The results demonstrated the hysteresis of separation points and the absolute increase of the largest negative pressure of the outer wall of the tower after involving the wind vibration. For the purposes of the inner wall of wind pressure, the absolute of the wind pressure coefficients were larger and the position of the internal high pressure zone had changed in comparison to omitting the wind vibration.This paper also analyzed the influence of wind speed and turbulence on the CFD simulation results of dynamic pressure, the analysis found that dynamic pressure was positively correlated with wind speed at the zonal angle of 90°, while the effect of wind speed on the dynamic pressure is more obvious in the top and bottom area at the zonal angle of 0°and 180°. The effect of turbulence on the dynamic pressure is relatively small, which may be related to the small value of amplitude extracted from the first main mode of transverse vibration. This paper also obtained wind load factor based on the CFD calculation results. The calculation result was 1.5075, while the data of the specification is 1.9, which showed the structural features of the lanky cooling tower met the design requirements of the wind load factor. |
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