流体通过涡激振动机翼的声辐射研究

Research on the sound generation by flow around vortex-induced vibrated aerofoil

为了有效地降低涡激噪声,研究了粘性流体通过涡激振动机翼的声辐射。采用Navier-Stokes方程描述二维机翼的流固耦合运动,用弹簧系统代替实际固体变形产生的回复力和力矩,翼型的运动是两个自由度,即垂直于来流的振荡和转动振荡;为了模拟涡激振动,机翼的初始攻角取得比较大,以便产生周期性的旋涡脱落及周期性的流体动力,后者与弹簧系统相耦合,引起振动,用Lighthill声比拟方法研究了由此引起的声辐射。计算结果表明:当涡脱频率和机翼的固有的振动频率一致时,发生锁定的现象,此时的声辐射达到最大。

In order to reduce efficiently the vortex-induced noise, the sound generation by viscous flow around vortex-induced vibrated aerofoil is studied. The fluid-structure coupled system of aerofoil in two dimensions is described by using Navier-Stokes equations. The reversing force and movement induced by body deformation are simulated by spring system. There are two degrees of freedom in aerofoil movement, that is the vibration vertical with incoming flow and the turning vibration. The initial attacked angle is so large that periodic vortex shedding and dynamic force could be produced. The latter is coupled with the spring system and vortex-induced vibration could be introduced. By using Lighthill' acoustic analogy, the sound generation induced by the viscous flow around the vortex-induced vibrated aerofoil in two dimensions is studied. The results show that lock phenomenon happens and the sound generation is the largest when the vortex-shedding frequency is coincided with the natural frequency of the aerofoil system