Experimental Study On The Control Of Transversely Oscillating Cylinder Wake

Base blowing and placing a small narrow strip in the wake were applied to suppress the vortex shedding of a transversely oscillating cylinder. The first part was using the base blowing to suppress the vortex shedding of a transversely oscillating cylinder. The main experimental parameters were: Re=V∞D/v=2100~6100, the non-dimensional vibration frequency were: 0≤feD/V∞≤0.34, 0≤Vb/V∞≤22.3, A/D=0.4 respectively. We can get the power spectrum at various points by measuring fluctuating velocity; the wake of a transversely oscillating cylinder before and after control could be recorded with the smoke-lines. Contrast fluctuating velocity power spectrum and smoke-lines pictures, we can get the control effect of a variety of base blowing velocity to the transversely oscillating cylinder wake. By analyzing fluctuation velocity spectrum of different oscillation frequency, the all experiment spectrum can be divided into three parts: the non-locked mode,the typical frequency-locked mode and the atypical-locked mode. In the non-locked mode and atypical frequency locked mode, vortex shedding can be suppressed by base blowing, while in typical frequency-locked area, vortex shedding can’t be suppressed.The second part of this article was about using a narrow strip to suppress vortex shedding of a transversely oscillating cylinder, the main experimental parameters were: Re=V∞D/v=1900~12200, 0≤fe D/V∞≤0.24, A/D=0.2 respectively, the width of the narrow strip mainly used was b/D=0.2. The all experiment spectrum can be divided into two parts: the non-locked area, the frequency-locked area. The narrow strip was effective to suppress vortex shedding of the non-locked area, but there was no obvious effect to the vortex shedding of frequency-locked region. By studying the effect of experimental parameters on the effective control region, we can found that when other conditions were the same, with the decrease of the dimensionless frequency and Reynolds number, the increases of small strip width, the effective control area increases. By stability analysis we can find that the narrow strip can change the wake instability of transversely oscillating cylinder, thereby vortex shedding nearly wake region can be suppressed.