Two-dimensional vortex-induced vibration suppression through the cylinder transverse linear/nonlinear velocity feedback

Abstract

Suppressing vortex-induced vibration (VIV) has recently attracted numerous researchers due to its practical significance in many engineering applications. Most of the previous studies have focused on a passive or active flow control. A structurally active control approach to mitigate a two-dimensional, nonlinear coupled, cross-flow/in-line VIV has not been well studied. This paper presents a reduced-order fluid-structure dynamic model and combined analytical-numerical solutions for the efficient suppression of two-dimensional VIV of a flexibly mounted circular cylinder in uniform flows. The theoretical model is based on the use of coupled Duffing-Rayleigh oscillators with three variables describing the cylinder cross-flow/in-line displacements and the strength of the fluid vortex circulation in the cylinder wake. These equations of fluid-structure motions contain geometric and hydrodynamic nonlinearities. Closed-loop linear and nonlinear velocity feedback controllers are implemented in the transverse direction governing the larger cross-flow response than the associated in-line counterpart. Approximated analytical expressions are derived by using the harmonic balance to explicitly capture the system nonlinear dynamic features and the effects of key dimensionless parameters. Parametric investigations are carried out to evaluate the linear versus nonlinear controller performance in terms of the maximum response suppression capability and the power requirement in a wide range of reduced flow velocities, mass ratios, and control gains. Over the main lock-in resonance region with coupled cross-flow/inline responses, the linear controller is found to be more efficient in suppressing the two-dimensional VIV by also modifying the system frequencies and phase relationships. Nevertheless, based on the power comparison, the nonlinear control is superior to the linear control for very small targeted controlled amplitudes of a very low-mass cylinder. These active control strategies may be further applied to the multimode VIV suppression of a long flexible cylinder with multi degrees of freedom.

Empirical sensitivity of two-dimensional nonlinear wake–cylinder oscillators in cross-flow/in-line vortex-induced vibrations

“…(i) The cylinder acceleration coupling term in Eqs. (6) and (8) It would be worthwhile to explore whether and how the velocity coupling (Ma and Srinil, 2017;Skop and Balasubramanian, 1997) affects the bi-dimensional fluid-cylinder dynamics sensitivity, and whether overall xy response predictions could be quantitatively improved. This is because the 2-DOF vs. 1-DOF VIV behaviours are relatively distinctive for cylinders with a low mass ratio m* < 6 (Jauvtis and .…”

Controlling self-excited vibration using positive position feedback with time-delay

“…Dai et al studied the effect of timedelayed feedback control on vortex-induced vibration. Effect of linear and nonlinear velocity feedback on vortex-induced vibration due to cross-and inline flow has been studied by Ma and Srinil [27].…”