涡方法用于桥梁断面气动导数和颤振临界风速的数值计算

Numerical Assessment of Aerodynamic Derivatives and Critical Wind Speed of Flutter of Bridge Decks by Discrete Vortex Method

利用快速离散涡方法计算桥梁主梁断面的气动导数 ,来流为二维粘性不可压缩均匀流。使用边界元及新颍涡量边界条件的积分表示方法计算表面涡量 ,引入快速多极子展开及系数影响矩阵技术获得无网格方法 ,并由此快速计算涡元速度。使断面分别在扭转及竖向做强迫正弦振动 ,利用离散涡方法分别计算其气动力 ,并根据最小二乘法获取气动导数 ,采用 Sacalan的半逆解法确定颤振临界风速。以南京二桥闭口箱梁断面 (方案一 )为例 ,计算结果显示与实测结果有着合理的一致性。

The aerodynamic derivatives are simulated using the fast discrete vortex method in two dimensional viscous incompressible flow passing the bridge decks. An efficient boundary element method and novel vorticity boundary condition method with integral representation are used to determine the surface vorticity. An efficient influence matrix technique and a fast adaptive multipole algorithm is used to obtain a mesh free method and the velocity of vortex elements is calculated fast. The aerodynamic forces of the deck undergoing a harmonic heave and pitch motion are computed by the fast discrete vortex method. The aerodynamic derivatives are simulated according to the computed aerodynamic forces by the least squares method and the critical wind speed of flutter is calculated with Scanlan's method. Fair agreement is established between the present simulation and wind tunnel test results of the Second Yangtsi Riverbridge of Nanjing.