矩形断面抖振力展向相关性的试验研究

为了研究紊流作用下钝体的非定常气动力(抖振力),以矩形断面为例,通过测压试验研究不同紊流积分尺度下的非定常气动力的分布特性,并结合理论分析方法研究了现有导纳识别方法的缺陷,进而提出基于三维统计理论的两波数三维导纳初步识别方法。结果表明:对于矩形这类钝体断面,其在紊流下的抖振力特性与流线型箱梁(桥梁主梁)接近,即抖振力的相关性高于脉动风速的相关性,且与紊流积分尺度成正比。另外,理论分析结果与实测数据间存在较大的差异,进一步表明传统的二维导纳函数无法反映真实的非定常气动力展向分布情况,而两波数的三维导纳则可揭示展向不同尺度漩涡都对抖振力的贡献。

EXPERIMENTAL INVESTIGATION OF THE SPAN-WISE CORRELATION OF BUFFETING FORCES ON A RECTANGULAR SECTION

In order to study the characteristics of unsteady aerodynamic forces (buffeting forces) on a bluff body, a rectangular cylinder is taken as an example. A pressure measurement technique was applied to study the span-wise buffeting force on the cylinder under turbulent flow with different integral length scales. The deficiencies of traditional 2-dimensioanl aerodynamic admittance were also studied by theoretical analysis, and a preliminary identification approach for 3-dimensional aerodynamic admittance based on statistical theory was proposed. The results show that the span-wise correlation of the buffeting force on rectangular section is larger than that of turbulence and is in proportion to integral length scale of wind fluctuations, which are similar to previous findings regarding streamlined bridge girders. The explicit difference between theoretical and tested results indicates that the traditional aerodynamic admittance can hardly reflect the span-wise distribution of unsteady aerodynamic forces. However, the 3-dimensional aerodynamic admittance with two-wave numbers can reveal the contributions of span-wise vortices with different dimensions to the buffeting force explicitly.