Study On Fluid-structure Interaction Of Transmission Line Based On CFD Overset Grid Method

Power industry is an important lifeline of national economic development and plays an extremely important role in national modernization construction.However,with China's economic development,more and more transmission tower-lines,more and more complex topography and climate have been crossed,and damage caused by wind vibration and galloping of transmission wires has been increasing in recent years.Due to the characteristics of small stiffness and low damping of large span transmission conductors,under wind load,strong coupling between conductors and air occurs,which may lead to unexpected coupling vibration of conductors and lead to serious consequences.Therefore,in this paper,the fluid-structure coupling of transmission lines is studied by numerical simulation in light wind vibration of transmission lines and galloping of iced transmission lines.By means of CFD numerical simulation method and overlapping grid technique,the flow field around a cylinder with smooth circular section and different Reynolds Numbers is simulated numerically.The cylinder aerodynamic parameters of Re=3900 are analyzed and compared with the previous experimental data and simulation data.The grid scheme,turbulence model and time step of numerical simulation are determined.Numeri cal simulation calculation Re=1.1×10~4,2.3×10~4,3.4×10~4,4.5×10~4,5.6×10~4,The results are compared to verify the accuracy of the simulation scheme in this paper,laying a foundation for wind induced vibration simulation of transmission conductor.The numerical calculation method of transmission conductor fluid-structure interaction is established,UDF(user-defined program)is written according to the runge kuta method to realize the docking with the main program,and the overset grid scheme is used to realize the real-time update of grid.Numerical calculation of vortex-induced vibration of elastic support wire of rigid column is completed.The vibration law of circular cylinder vortex vibration was studied by changing the wind speed reduction,the vibration result of single degree of freedom was compared with the wind tunnel test results,and the influence of multi-degree of freedom on the vortex vibration of wire and the vibration track of wire under multi-degree of freedom were analyzed.By changing the cross section of the wire into a crescent ice overburden section,the vortex-induced vibration response of the crescent section and the influence of different degrees of freedom and different torsional stiffness on the vortex-induced vibration and aerodynamic parameters were further analyzed.The results show that the release of the degree of freedom along the wind will amplify the amplitude of the transverse wind,and the vibration path is elliptical.On the basis of the numerical simulation of the vortex induced vibration of the crescent-ice section,the fluid-structure interaction numerical simulation of the tripping of crescent-ice traverse was carried out to improve the wind velocity of incoming flow.Based on the quasi-steady hypothesis,the aerodynamic coefficients of iced traverse are simulated to obtain the DenHartog coefficient and Nigol coefficient.The wind attack Angle range of possible tripping of crescent iced traverse is analyzed,the vibration characteristics under different wind speeds are studied.Release the degree of freedom in cross-wind direction,study the vibration characteristics under different wind speeds,and obtain the aerodynamic damping of the conductor by processing th e vibration time-history signal.The effects of different degrees of freedom,different wind attack angles and different wind speed on the draught amplitude are studied.