Study On Flutter Behavior And Control Measures Of Long Span Bridge Based On OpenFOAM

Due to the growing demand for super long-span bridges,the bridge became softer and softer,which makes the wind-induced vibration of bridges more prominent.Flutter is the most destructive wind-induced phenomenon,which needs to be considered in bridge design.The increasing performance of computers makes the rapid development trend of numerical simulation technology.With the maturity of computational fluid dynamics（CFD）,it has become an important means of scientific research together with physical experiments.At this stage,there is various numerical simulation software to choose from.Among them,OpenFOAM is one of the most common open-source CFD software using polyhedral mesh,which has free programming environment It has the advantages of convenient function development.In view of this,the flutter control effect of anti-phase movable winglet and the application of OpenFOAM in the flutter field of long-span bridges are studied,mainly including the following contents:1.Based on the forced vibration theory,the flutter derivative identification script is compiled.Two different dynamic grid methods are used to verify the accuracy of flutter derivative identification of OpenFOAM,and the sensitivity of the main parameters involved in the identification process is studied.The results show that the segment model of bluff body bridge is more sensitive to Reynolds number and wind attack angle,and the dimensionless amplitude of vertical bending is less than 0.025 The torsional amplitude less than 2°is very important for flutter derivative A₁^*and A₂^*identification accuracy.2.A support system is designed and manufactured.The driving device is added while the traditional support segment model function is continued so that the movable wing can spin with the main beam movement.The results show that the winglet can control the flutter well and improve the critical wind speed of the flutter.The streamline segment model is improved by 12.9%and the model of the blunt segment is increased by 12%,but the movable wing increases the critical flutter speed and increases the amplitude of the vortex.3.This paper studies and proposes a numerical simulation method to realize the segmental model of bridge with movable winglet.Python script is used to obtain the motion state of the segmental model and calculate the rotation angle.The displacement is given to the movable winglet by controlling the time step.New functions are added to realize the dynamic simulation of the segmental model of bridge with movable winglet without changing the original dynamic mesh solver of OpenFOAM The numerical simulation function and the flutter control effect of the movable wing are compared with the experiment.