This paper deals with the active control of the compressible flow past a bluff-body by means of external acoustic sources. We successfully suppress the transition leading to the von-Karman vortex street. The derived adjoint-based framework allows the determination of the corresponding acoustic sources for generic bluff-body shapes. In particular, we determine the optimal spatial position for the control, i.e. where the acoustic source is most efficient, and the associated temporal signal. For the proposed example, a two-dimensional cylindrical body, the resulting acoustic actuation is anti-symmetric and harmonic. We found that the limits of our control approach are related to the limits of linear acoustics. The methodology and the results proposed in this paper can be used to design a control strategy coupled with a continuation procedure able to obtain the unstable solutions beyond the critical threshold.

本文利用外部声源，对通过钝体的可压缩流进行主动控制。我们成功地压制了通往von-Karman涡街的过渡。派生的基于伴随的框架允许确定通用虚张声势形状的相应声源。特别是，我们确定控制的最佳空间位置（即声源最有效的位置）以及相关的时间信号。对于所提出的示例（二维圆柱体），所得的声激励是反对称的和谐波的。我们发现控制方法的局限性与线性声学的局限性有关。