Investigation of wake-induced vibration interference between two staggered wave-cone cylinders at subcritical Reynolds number

<p dir="ltr">The wake induced vibration (WIV) of a one- and two-degree-of-freedom (1DOF, 2DOF) downstream wave-cone cylinder (WCC) behind a stationary equal-size upstream wave-cone cylinder in the staggered arrangement is numerically investigated at subcritical Reynolds number of 3 900 by using shear stressed transfer (SST) <i>k - ω</i> turbulence model. The streamwise pitch ratios (<i>P / D</i>_<em>m</em>) vary from 4 to 6 with a fixed incident angle <i>α</i> = 8°. Experimental measurements were also performed for the validation of the present numerical models. It is found that the largest vibration amplitude in crossflow direction occurred at <i>P</i> / <i>D</i>_<em>m</em> = 4, <i>U</i>_<em>r</em> =8 with small difference of streamwise vibration at <i>P</i> / <i>D</i>_<em>m</em> = 4, 6. Different from single wavy-cone cylinder (SWCC), the downstream flexible one of a pair staggered WCCs got larger vibration amplitude during phase switching stage instead of in-phase stage. The upstream wake will suppress the triple frequency of main frequency in the power spectra density (PSD) functions of <i>Cl</i> but stimulate the double one of that. An intriguing vibration mechanism happened in all 2DOF cases where the trajectory of downstream WCC is a significant ellipse rather than a figure of 8. The transformation of phase switching and the variation of the main frequency of drag coefficient (<i>Cd</i>) can be explained by the vortex-shedding modes of downstream WCC.</p>