带上水线拉索绕流场的大涡模拟研究

Large Eddy Simulation of Flow Around Stay Cable with Upper Rivulet

摘要:

针对带上水线的拉索模型，采用大涡模拟方法研究了水线和拉索的气动性能与绕流场流态之间的内在关系.结果表明，带水线拉索的绕流场呈现三种不同的流态结构.当上水线位于0°~50°时，水线对拉索绕流场的影响不大；当上水线位于50°～70°时，拉索上表面剪切层在上水线上分离后会再附着在拉索表面形成分离泡，并使拉索上表面受到很大的局部负压作用；当水线处在70°～90°时，凸起的上水线会导致上侧剪切层分离后远离拉索上表面.分离泡在拉索上表面周期性地出现和消失是斜拉索风雨激振的主要原因.

Abstract:

To understand the relationship between the flow field characteristics and aerodynamics of the cable with the upper rivulet, the flow around and aerodynamic characteristics of a cable model with an upper rivulet were investigated using large eddy simulation (LES) in the subcritical regime. The results show that there exist three distinct flow regimes with the rivulet located at different positions. In the range of θu=0°~50°, the rivulet has little influence on the cable. In the range of θu=50°~70°, with the interferences of the upper rivulet, the upperside shear layer of the cable which is detached from the rivulet can reattach on the cable surface and form a single separation bubble at the upper side of the cable, which induces an asymmetrical pressure distribution on the cable surface. In the range of θu=70°~90°, the upperside shear layer detaches at the rivulet, which causes a lower negative pressure on the upperside surface compared to those of the lowerside of the cable. It is concluded that the appearance and disappearance of the single separation bubble are the underlying reasons for the occurrence of the rainwindinduced vibration (RWIV).