The response of turbulent flow to the disturbance of a vibrating ribbon

By use of the LDV, experimental investigation was carried out for a turbulent boundary layer which was disturbed with an electric-magnetic vibrating ribbon. It is found that, in the flow, the response of the disturbance contains harmonic components besides the fundamental frequency of the ribbon vibration. The fundamental and harmonic disturbances can also enhance the energy of other frequency components around them. In the experiments, the regular disturbane was introduced in the outer region of the boundary layer. Under the given flow conditions, they can significantly influence the downstream coherent structures in the wall region by suppressing the bursts and increasing their period. The effect on the burst period depends on the disturbing frequency. The project supported by the National Natural Science Foundation of China