近距离双幅并行连续刚构桥箱梁断面静力三分力系数CFD计算

CFD Calculation for the Static Aerodynamic Coefficients of Box Girder Section of Continuous Rigid Frame Bridge with Close Twin Deck

采用CFD软件FLUENT计算了三水河大桥这种近距离双幅并行连续刚构桥箱梁不同断面在不同风攻角和有无护栏情况下的静力三分力系数,与风洞试验结果进行了对比,分析了三分力系数随不同影响因素的变化规律。结果表明:CFD计算结果总体上与物理风洞试验结果吻合较好,对上游桥阻力系数精度较高,对下游桥阻力系数及两幅桥的升力系数和扭矩系数误差稍大;箱梁断面阻力系数随风攻角变化较小,受梁高和有无护栏影响较大,来流风对上游桥的作用为较大的推力,对下游桥的作用为相对较小的吸力;上下游桥的升力系数和扭矩系数绝对值明显低于上游桥的阻力系数,其值也受风攻角、梁高和有无护栏等因素的影响而变化。

Sanshuihe Bridge is taken as an example, which is a continuous rigid frame bridge withclose twin deck on Xianyang-Xunyi Highway. Aerodynamic forces on the different section of the box girderwith or without guardrail and in different wind angle of attack are simulated by FLUENT. The static aero-dynamic coefficients gained by CFD are compared with wind tunnel test results, and the variation with thedifferent factors is analyzed. The results show that the CFD results are in good agreement with the windtunnel test results in general, and have high accuracy in upstream section resistance coefficient and rela-tively larger error in downstream section resistance coefficient and lift coefficient and torque coefficient ofsection in up and down stream; the resistance coefficients are affected small by wind attack angle, largelyby the girder section＇s height and guardrail, and the effect to upstream sections are strong push, but rela-tively weak suction to downstream sections; the absolute value of the lift and torque coefficients in up anddown stream are significantly lower than the resistance coefficients in upstream, and will change with theinfluence of the wind attack angle, dimension of section, guardrail and other factors.