| Solar thermal power is a hot international research topic,and trough solar p ower generation is an internationally dominating technique with a good commercialization prospect.Since solar thermal power stations are normally located in an open,flat area,wind load has to be properly controlled in its structural design.The trough s olar collector surface is in an arch shape with a low height,and it 's near ground wind field and wind pressure distribution are complex.But there are few researches on wind load and wind-induced dynamic responses done regarding such structure in China.And the wind resistance design of trough concentrator is in accordance with the existing specifications or technical standard of foreign countries.However,due to different geographical features and climate conditio n,the requirements on the strength and rigidity of the concentrator group cannot be met by designing in accordance with such codes.The structure design of trough solar collector system must meet the requirements that the system could work in force 6 wind,and not be destroyed in force 8 wind.In the working process,the mirror need to ensure that the sun light after the reflection accurate projection to the heat collection pipe,otherwise it will cause some loss of energy,and reduce the power generation of the trough solar collector system.These problems are urgently needed to solve in China's solar thermal power generation,while there is very little relevant research in the domestic.Due to the use of functional requirements of trough solar collector,the mirror needs to rotate its pitch angle to follow the sun,and in this process i ts shape,mass distribution and stiffness vary in different degrees.Trough solar collector is the structure of the variable shape,the variable mass,the variable stiffness,the research on the dynamic characteristics and dynamic response of this kind of structure is relatively rare at home and abroad,but this research has a certain value of theory and engineering application.In this paper,wind tunnel test,theoretical an alysis,numerical simulation and field measurement are used to analyze the wind resistance performance of the trough solar collector system,including the wind pressure distribution of the trough solar collector,fluctuating characteristics of wind pressur e,dynamic characteristics analysis,wind-induced response and equivalent wind load etc.The main results are as follows:(1)The distribution features of mean wind pressure coefficient and fluctuating wind pressure coefficient on mirror surface under different pitch angle and wind angle were obtained by conducting wind tunnel pressure-measurement experiments on trough solar collector model.Meanwhile,the pattern and characteristics of wind pressure distribution on mirror surface were analyzed with pitch angle and wind angle changes,and this paper provides the mean wind pressure coefficient contour map of collector under the most unfavorable conditions.This paper quotes the results of numerical simulation in the relevant literature,and compares with the results of wind tunnel tests,which verify the probability of the numerical wind tunnel simulation used in wind effects on trough solar collector.Besides the wind tunnel test is adopted to analyze the wind pressure distribution and flow field change situation of the trough solar collector under the interference condition,and provided the regulation of the drag coefficient CFxand the lift coefficient CFzof the collector with the change of pitch angle under the single condition and interference condition,and the experimental results were compared with other literatures.(2)By the high frequency dynamic balance test of force measuremen t of the trough solar collector model,we obtain the regulation of six wind(torque)coefficients with the change of pitch angle and wind angle under the single condition and interference condition,and studies the interference characteristics of collector s.This paper extracts the maximum value of six wind torque coefficient and the conditions of the maximum value occurred,and these results could provide a basis for the follow-up of trough solar collector structure design and optimization analysis.The drag coefficient CFx,lift coefficient CFz,base overturning moment coefficient CMy of the pressure test and the force test of trough solar collector are contrasted,which can verify the accuracy of the two test methods.(3)Through the analysis of the variation law of fluctuating wind pressure power spectrum of trough solar collector under different conditions to explore the main effect factors of fluctuating wind pressure.The article gi ves non Gaussian discriminant criterion of wind pressure distribution of the trough solar collector,and adopts the probability density distribution histogram and the pressure history curve of non Gaussian measurement points for further verification.Using the total probability approximation method to calculate the extreme wind pressure coefficient,and this paper gives the extreme wind pressure coefficient contour map of trough solar collector under the typical conditions.(4)By the software ANSYS this paper makes the modal analysis for trough solar collector,the calculation results of the dynamic characteristic parameters of the collector are obtained.The field measurement of the prototype of the trough solar collector in a certain place are carried out,and we get the the measured results of the dynamic characteristic parameters of the trough solar collector.The results of numerical simulation and field measurement are compared and analyzed.In general,both obtained results agree well,indicating that the finite element model of the trough solar collector is applicable.(5)Based on modal analysis of the finite element model of the trough solar collector,transient analysis is made in this paper,and the peak displacement response is obtained,the conclusions is that the maximum value of peak displacement response appears at the edge position of mirror which is located in far from the supporting structure,and these areas should be strengthened in the supporti ng structure stiffness when carrying out structural design of collector.In addition,in order to facilitate the use of the structure designer,the wind vibration coefficient of the measuring point under typical operating conditionsis given in this paper.(6)The multi modal force method of the trough solar collector is used to calculate the wind vibration coefficient,and we compare the results with the analysis of time domain method.The results show that multi modal force method has low computational cost and higher calculating precision,therefore,the multi modal force method is more suitable to calculate the equivalent wind load for the trough solar collector.Finally,the calculation formula for the equivalent wind load of mirror and the overall force of the trough solar collector system are provided.The focus is that the local wind load shape coefficient values and wind vibration coefficient value of collector under the most unfavorable conditions are given.At the end of the paper,the equivalent wind load of the trough solar collector in the most unfavorable condition is given,and these results can provide a reference for the structure design of the trough solar collector system. |
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