Numerical Simulation Of Fluid Solid Coupling Of A New Type Molten Salt Collector Under Wind Load

With the concept of sustainable development being deeply rooted in the hearts of the people,the tower solar thermal power generation technology has made rapid progress,and many countries have listed it as a key development industry.As the core component of the tower solar thermal power generation system,the new molten-salt power tower is the focus of structural design.The prominent features of the tower are:large ratio of height to width,large concentrated mass of collector at the top,and obvious abrupt section at the junction of concrete tower body and collector.Due to these characteristics,the tower belongs to the wind sensitive structure,and the wind load should be considered in the structure design.However,the current domestic load code only stipulates the calculation method of wind load for circular section structure with no sudden change in section and mass,which can not meet the relevant requirements of the tower structure design.Therefore,this paper takes the tower structure provided by a design institute as the prototype,uses CFD three-dimensional numerical simulation method to study the wind field around the tower,the wind pressure distribution on the tower surface and the shape coefficient(1)Based on the fitting results of three-dimensional numerical simulation and experimental data of CAARC standard high-rise building,the calculation domain parameters and turbulence model used in this paper are determined.According to the existing data,the simplified workbench model of the tower is established,and the unidirectional and bidirectional fluid structure coupling analysis is carried out.The research results show that:the maximum wind pressure appears above the windward side,the windward side of the tower has an obvious symmetrical split line,there is a large wind pressure difference in the junction range of the tower,and the maximum pressure difference on the tower surface is 5042 when the bidirectional fluid structure coupling is applied The maximum displacement of the top center of the tower is199.8 mm,which is about two times of the maximum displacement of 98.4 mm calculated by one-way fluid structure coupling.Fourier transform is used to calculate the time history curve of the two-way fluid solid coupling tower,and the main frequency of swing of the tower is0.2734 Hz,which is 0.0005 Hz different from the solid model.It shows that the tower studied in this paper is dominated by the first array under wind load.(2)The effects of basic wind pressure,collector diameter and collector height on the wind field around the tower,the wind pressure coefficient on the structure surface and the maximum displacement of the top center are analyzed.It is found that when the basic wind pressure increases from 0.4 k N/m~2 to 1.0 k N/m~2,the maximum wind pressure of the corresponding wind field increases from 947.13 Pa to 2367.06 Pa,and the maximum displacement of the tower top center increases by 12.3 mm on average;when the diameter increases from 18 m to 28.5 m,the corresponding wind field variation difference does not exceed 31 Pa,and the maximum displacement increases by 3.25 mm on average;when the height increases from 31 m to 39 m,the corresponding wind field variation difference is only 10 mm The maximum displacement increases by 2.1 mm.It shows that the effect of basic wind pressure is the biggest,the change of collector diameter is the second,and the change of height is the least.(3)The overall structure of the collector follows the general rule of flow around a cylinder,but the wind pressure distribution at the variable section of the tower interface is extremely complex.When the diameter and height of the collector change,the shape coefficient of the structure can not fully refer to the circular section of the standard.The local shape coefficient and the overall shape coefficient of the collector are analyzed according to the current standard,It is found that the change of the diameter and height of the collector has little influence on the shape coefficient of the side of the tower and the top of the collector,and has great influence on the shape coefficient of the interface between the side of the collector and the tower,and the local shape coefficient of the side of the collector and the side of the tower is more consistent with the recommended value of the circular section structure in the load code for building structures(GB 50009-2012)on the windward side,There are some errors on leeward side.The change of collector diameter has more significant effect on the overall shape coefficient than the change of collector height.