| This project is supported by the National Natural Science Foundation of china,"Aeolian vibration effect and fatigue life evaluation of high voltage overhead transmission line in the thermal mechanical coupling field"(Grant No.51578512).High voltage overhead transmission is the main mode of power supply in China.With the rapid development of China's economy,the power consumption demand is gradually increasing,the bottleneck problem of transmission ability of power grid becomes more and more severer during seak times.On the premise of ensuring safe operation of the grid,capacity expansion and transformation of existing High-Voltage power transmission line and improving the current norms of high voltage transmission wire operating temperature can increase the stability of the power system.So that can improve and fully tap the transmission potential and reduce all sorts of investment cost and social cost because of the new high voltage transmission lines.It is important for the sustainable development of China's economic and social significance.In the normal operation of high-voltage voerhead transmission lines,Joule heat caused by current carrying is the main factor in the temperature rise of power lines.So,the rapid and efficient heat exchange between the transmission line and the external environment is an important guarantee for stable transmission capacity and ensuring high current carrying capacity.Under the current technical conditions,the main way of heat exchange between the transmission line and the external environment is the convection heat transfer(including natural convection and forced convection)caused by the temperature difference between the wire and the external environment.In the forced convection heat transfer model,the wind flow also causes the vibration of the transmission line,in which the probability of occurence of aeolian vibration is the largest and the longest duration.In the past research,the study of wind-induced vibration around the transmission line has always been a hot spot,but most of the research is focused on the performance of the transmission line.The influence of wind-induced vibration on the heat transfer performance of the transmission line is relatively insufficient.In fact,long-term moderate wind-induced vibration(such aeolian vibration)can enhance the heat transfer of transmission line and improve the steady capacity of the transmission line,viewed from electrotechnicsand heat transfer.Therefore,from the point of ensuring the maximum dynamic capacity of the line and meeting the electricity demand during peaks,there are great theoretical significance and research value to further study enhaced heat transfer characteristics caused by aeolian vibration,and which also can provide technical support for daily management and maintenance of high-voltage transmission lines.In this dissertation,the computational fluid dynamics and the computational structure dynamics are employed to study the flow characteristics of transmission line and heat transfer characteristics.Dynamic mesh in Fluent isused in the simulation of fluid-structure interaction,the comparison was taken between calculation results and classical results so as to validate the availabilityof CFD method.The aeolian vibration of single conductor and bundle conductor was simulated employing Fluent and the variation regularity of the force coefficients,the amplitude of vibration and the heat transfer characteristics in different cases are studied.The specific contents are as follows:Firstly,Fluent software is used to study the aerodynamic characteristics and heat transfer characteristics of fixed single conductor,and the two boudary cond itions,constant heat flux and constant wall temperatur,are considered.Comparison is taken between calculation results and experimental correlation formula so as to validate the availability of CFD method.The fitting formula of the Nusselt number with Reynolds number is obtained,which is consistent with the actual operating environment.Secondly,Vortex-induced vibration for the Re=200 is simulated with Fluent software.The results of simulation is in good agreement with the literature.Then the effect of vibration on the heat transfer is considered to get the effect of amplitude and lock range on heat transfer.The study of single conductor vibration on heat transfer by adjusting the wind speed to the actual operation condition to get the influence of structure parameters and Reynolds number on heat transfer.Thirdly,Having considered the fact that the actual high-voltage transmission lines are mostly in the form of slit wires,the effects of different arrangement modes and sub-conductor spacing ratio on the aerodynamic characteristics and heat transfer effect of double split wire are analyzed in this paper. |
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