∏型断面竖向涡振过程气动力不同分量的演变特性OA北大核心CSTPCD

Compared with the traditional streamlined box girder,the typical Π-shaped open section is prone to vortex-induced vibration(VIV)because of its high section bluff configuration.In this research,the simultaneous vibration and pressure vibration of wind tunnel tests and computational fluid dynamics(CFD)are used for studying the characteristics of the pressure distribution along the surface of the typical open section and the nonlinear phenomena such as different aerodynamic components and hysteresis characteristics.First,the initial characteristics of the local pressure in different periods in the VIV lock-on region are analyzed.Secondly,the CFD dynamic grid method is used to realize the fluid-solid coupling analysis of the section.On this basis,the different frequency components of the aerodynamic forces in the VIV process are decomposed by the Hilbert vibration decomposition(HVD)method.The research results show that the average surface pressure on the leading edge of the opening section is in the negative pressure zone,where the airflow is separated.At the extreme point of the VIV,the pulsating pressure changes most violently in the area of 0.1<X/B<0.3,indicating that the vortex shedding intensity is the largest in this region,and the analysis shows that the aerodynamic forces on the opening section have obvious high-order components.Due to the existence of high-order harmonic components,the degree of nonlinearity of aerodynamic force is continuously deepened,and the work done by each order component of aerodynamic force has different characteristics in one whole vibration period.Among them,the first-order component F1 of the aerodynamic force exhibits a curvilinear increase in work during the vibration period,showing an overall increasing trend.The hysteresis curve of the second-order component F2 of the aerodynamic force presents a complex"8"ring shape.The influence of the third-order and above components on the VIV system can be ignored.