竖向紊流积分尺度影响下的流线型箱梁断面抖振升力空间分布特性及理论建模

THREE-DIMENSIONAL CHARACTERISTICS AND THEORETICAL MODELING OF BUFFETING FORCE ON STREAMLINE BOX GIRDER

  • 摘要: 为研究竖向紊流积分尺度对于流线型箱梁抖振升力空间分布特性的影响,开展了刚性节段模型测压试验。该文选用竖向紊流积分尺度相差较大的三类流场,用于研究无量纲尺度Lw/B(竖向紊流积分尺度与桥梁宽度之比)对抖振升力空间分布特性的影响规律,提出考虑紊流三维效应影响的流线型箱梁断面三维抖振升力广义模型。结果表明:Lw/B为影响流线型箱梁断面抖振升力空间分布特性的关键控制参数,桥梁紊流三维效应随着Lw/B的降低而显著提高。同时,因风嘴、斜腹板等气动措施显著降低了流线型箱梁断面迎风侧气流的流动分离,使得不同竖向紊流积分尺度下其抖振升力二维气动导纳基本保持不变,表明由竖向紊流积分尺度对该型桥梁抖振升力荷载的高频畸变影响可以忽略,可为流线型箱梁断面结构气动外形优化提供参考。

     

    Abstract: In order to study the effect of vertical turbulence scale on the spatial distribution characteristics of buffeting lift in a streamlined box girder, a rigid section model pressure test is carried out. In this paper, three types of flow fields with obvious differences in vertical turbulence integral scale are selected to study the effect of dimensionless scale Lw/B (ratio of the vertical turbulence scale to the structure width) on the three-dimensional characteristics of buffeting lift. A generalized three-dimensional buffeting lift model of a streamlined box girder is proposed considering the three-dimensional effect of turbulent flow. The results show that Lw/B is the key control parameter in determining the three-dimensional buffeting lift characteristics of the streamlined box girder section. It is observed that the three-dimensional turbulence effect of the bridge becomes mire significant when Lw/B decreases. Meanwhile, the flow separation of the airflow on the windward side of the streamlined box girder section is significantly reduced with the use of aerodynamic measures, such as the nozzle and the inclined web. Therefore, the two-dimensional aerodynamic admittance of the buffeting lift of the streamlined box girder remains unchanged under different vertical turbulence scales, which indicates that the effect of the vertical turbulence scale on the high-frequency distortion of the buffeting lift load of the bridge can be ignored, and it can provide a reference for optimization of the aerodynamic shape of streamline box girder section structure.

     

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