Investigation and Mitigation of Vortex Induced Vibration Using a Cyber Physical System

Abstract

The Cyber Physical Aeromechanic System (CPAS) is a test bed for fluid-structure interaction studies. The CPAS is a 2nd-order state space system and tests three dynamic systems: a pendulum, vortex-induced vibration (VIV) with a nonporous cylinder, and VIV mitigation with porous cylinders. The CPAS was verified with MATLAB state-space simulation, a mass spring damper, and a pendulum. The simulation, mass spring damper, and pendulum were used to systematically build and test the CPAS. The validated CPAS was then used to accurately recreate the findings of the VIV study performed by Govardhan et al. in 2000. The CPAS used porous cylinders to disrupt the shedding vortices and mitigate VIV. The flow fields from the VIV studies for both nonporous and porous cylinders were captured using Particle Image Velocimetry (PIV). The five modes of VIV, C(2S), 2S, 2Po, 2P, and NC are all present with the nonporous cylinder, while the presence of pores in the cylinders interrupt the vortex shedding and reduce the amplitude of oscillation. With a porous cylinder two hole diameters apart, the VIV was not present for any U* values. For the porous cylinder with seven hole diameters apart, the VIV oscillation was present until the transition between the 2S and 2Po modes.