| With the quick growth of country’s economy,the demand of energy has increased significantly.Among them,electric energy is widely used in life because of its safety,environmental protection and efficient transmission.But in recent years,the energy transmission base is more and more far away from the lack of resources,and the power supply can only be transmitted through long-distance long-span transmission lines.At present,the transmission tower in long-span transmission lines often uses super high circular section steel tube tower,and it has the feature of low weight,tall softness and little damping,which is easy to be damaged under the strong wind,so in actual project,wind load is regarded as the major dominate load.The wind load features of Chizhou Yangtze River long-span transmission tower in Anhui Province are studied based on CFD numerical simulation method in this article.Combined with the fitting formula of shape coefficient of circular section tower,wind vibration reply of the whole tower model is reasearched.In this article,the following work was executed:(1)On the basis of verifying the feasibility of CFD numerical simulation,a fullscale model of lattice circular section steel tube tower is established,and the variation of shape coefficient of circular section steel tube tower under different wind direction,compactness,wind speed and aspect ratio is studied by steady-state simulation method.The results show that the shape coefficient of tower gradually decreases with the increase of compactness(wind resistance coefficient),and the shape coefficient of x-direction and y-direction wind load first increases and then decreases in the range of 0°-90°.The maximum value is obtained when the wind direction angle is 15° and 75° respectly.In the region of supercritical Reynolds number,there is no clear correlation between shape coefficient and wind speed and the shape coefficient of the tower increases with the increase of the aspect ratio.The results of CFD simulation in this paper are close to GB 5009 code、DT / L 5254 code and New Zealand NZS-7000 code.(2)Based on the large eddy simulation(LES)method,the drag coefficient and lift coefficient of the scale model of circular section steel tube tower are calculated.The change rule is discussed in time-area,and is also discussed in frequency-area.The average value of drag coefficient drops when the wind velocity grows,and its power spectrum has a wider band peak and wider energy distribution,while the mean value of lift coefficient tends to 0,and its power spectrum has a very obvious narrow-band peak.The pulsating components of the two are more stable at low wind speed and gradually decrease at high wind speed.At the same time,the drag coefficient and lift coefficient can be seen from the calculation results The mean value of force coefficient is almost not affected by turbulence,but its pulsating component will gradually increase with the increase of turbulence.Through the post-processing software,the pressure distribution and flow field characteristics of the tower can be further understood.(3)The simulation program of fluctuating wind speed is compiled by using MATLAB software to generate pulsation wind load of class B topography,and the wind vibration reply of the whole tower is researched based on ANSYS finite element analysis software.The results show that there is small discrepancy in the wind vibration reply of the large span steel tube tower in the downwind direction between 0° and 90°.The displacement reply grows gradually,so does the acceleration reply as the highness grows.When the main material(# 2)on the windward side of the transmission tower is at the bottom of the transmission tower,it is in the compression state.With the increase of the height,it will gradually become the tension state,while the main material(# 4)on the leeward side is always in the compression state.The wind vibration reply coefficient of large span steel tube tower when the highness increases,and there is a sudden change at the three cross arms.The wind-induced vibration coefficient calculated in load code for overhead transmission line is larger than that of numerical simulation,and tends to be conservative. |
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