Theoretical And Wind Tunnel Experimental Study On Aerodynamic Characteristics Of Shielding Ring

In recent years,the rapid development of my country’s national economy has brought about a sharp increase in the demand for electricity,which makes people pay more and more attention to the safety of transmission lines.The shielding ring on the tension tower of the long-distance transmission line can effectively reduce the non-uniformity of the electric field,suppress the discharge phenomenon and protect the safety of the line.At present,most of the research on shielding rings is focused on the electrical properties,and the research on its mechanical properties,especially its aerodynamic properties,is very scarce.This paper mainly studies the aerodynamic characteristics of the shielding ring.By designing a scaled model of the shielding ring for wind tunnel tests,combined with the vibration measurement data,the aerodynamic force of the model when the vortex-induced resonance occurs is identified,and the aeroelastic response of the system is found.Variation of characteristics with parameters.The main contents of this paper are as follows:(1)The natural vibration characteristics and damping characteristics of the reduced-scale model of the shielding ring are studied,the rationality of the model design is demonstrated,and the theoretical basis for the wind tunnel test is provided.(2)Wind tunnel experiments with different inclination angles were carried out on the scaled model.The study found that the converted starting wind speed of the model is roughly the same;with the continuous increase of the wind speed,the amplitude response of the model presents a "ji"-shaped trend,and an obvious locking phenomenon occurs;with the continuous increase of the model inclination angle,the vortex The length of the locking interval of the excited resonance has an obvious decreasing trend.When the wind speed exceeds the locking interval,the vortex vibration response will decrease rapidly.(3)According to the wind tunnel test data,theoretical calculation of aerodynamic parameters is carried out.It is found that the aerodynamic damping parameters and aerodynamic stiffness parameters in the empirical linear model increase with the increase of the dimensionless frequency,and the value of the periodic excitation parameter is small;the identification of the periodic excitation parameter is ignored in the empirical nonlinear model,and the aerodynamic damping parameter increases with the increase of the dimensionless frequency.The increase of the dimensionless frequency first increases and then decreases,the aerodynamic stiffness parameter increases monotonically with the increase of the dimensionless frequency,and the variation law of the nonlinear damping parameter is not fixed.(4)The aerodynamic forces in the empirical model are calculated.The results show that:in the linear model,the proportion of each aerodynamic term in the vortex excitation force is different,the aerodynamic damping term accounts for most of the vortex excitation force,and the aerodynamic stiffness term accounts for a small proportion,and the overall recognition error of the linear model is large;In the nonlinear model,the vortex excitation force mainly comes from the damping term.The linear aerodynamic damping term accounts for about half of the vortex excitation force,and the nonlinear aerodynamic damping ratio is slightly smaller than the former.The overall aerodynamic identification error is small,which is suitable for Aerodynamic identification of shielding rings.