Selective Surface Roughness to Suppress Flow-Induced Motion of Two Circular Cylinders at 30,000 < Re < 120,000

Abstract

D epartm ent o f Naval A rch ite ctu re and M a rin e E n g in e erin g, U n iv e rs ity o f M ic h ig a n , A n n A rb o r, M l 4 8 1 0 5 e -m a il: h rp a rk @ u m ic h .e d u S e le c tiv e S u rfa c e R o u g h n ess to S u p p ress F lo w -In d u c e d M o tio n of T w o C irc u la r C y lin d e rs at 3 0 ,0 0 0 < R e < 1 2 0 ,0 0 0 M ic h a e l M . B e rn its a s 2 P ro fe sso r D epartm ent o f Naval A rc h ite c tu re and M a rin e E n g in e erin g, U n iv e rs ity o f M ic h ig a n , A n n A rb o r, M l 4 8 1 0 5 e -m a il: m ic h a e lb @ u m ic h .e d u Eun S o o K im D epartm ent o f Naval A rch itectu re and M a rin e E n g in e erin g, U n iv e rs ity o f M ic h ig a n , A n n A rb o r, M l 4 8 1 0 5 e -m a il: b b lw ith @ u m ic h .e d uIn the Marine Renewable Energy Laboratory of the University of Michigan, selectively located surface roughness has been designed successfully to suppress vortex-induced vibrations (VIV) of a single cylinder by 60% compared to a smooth cylinder. In this pa per, suppression of flow-induced motions of two cylinders in tandem using surface rough ness is studied experimentally by varying flow velocity and cylinder center-to-center spacing. Two identical rigid cylinders suspended by springs with their axes perpendicular to the flow are allowed one degree of freedom motion transverse to the flow direction. Suiface roughness is applied in the form of four roughness strips helically placed around the cylinder. Results are compared to smooth cylinders also tested in this work. Ampli tude ratio AID, frequency ratio f osclfn.water, and range of synchronization are measured. Regardless of the center-to-center cylinder distance, the amplitude response of the upstream smooth cylinder is similar to that of an isolated smooth cylinder. The wake from the upstream cylinder with roughness is narrower and longer and has significant influence on the amplitude of the downstream cylinder. The latter is reduced in the initial and upper branches while its range of VTV-synchronization is extended. Galloping is suppressed in both cylinders. In addition, the amplitude of the upstream rough cylinder and its range of synchronization increase with respect to the isolated rough cylinder.

URANS-Based Prediction of Vortex Induced Vibrations of Circular Cylinders

“…Application of PTC as a step on the cylinder returned satisfactory results with CFD in the TrSL3 flow regime. On the contrary, CFD results for smooth cylinders agree with experiments for lower Reynolds numbers only as Park et al (2014) suggested although a subsequent study of Kinaci et al (2016b) have shown that it is also possible to obtain good accordance with experimental results at even higher Reynolds numbers. Steven et al (2016) investigated the flow around an elastically mounted cylinder using LargeEddy Simulation (LES).…”

“…In some studies such as (Ding et al, 2013;Wu et al, 2014;Park et al, 2014), it has been suggested that the boundary layer separation on a fixed cylinder at > 10000~12000 (some references say > 20000 ) cannot be predicted accurately which results in the failure of simulating numerically the smooth cylinders in VIV. Although this may partly be correct, it has been shown in this section that there is satisfactory accordance with experiments until the cylinder experiences drag crisis in the critical (near > 3 • 10 ) and the supercritical (around 3 • 10 < < 10 ) regions.…”

Virtual Spring–Damping System for Flow-Induced Motion Experiments

“…2.2 Physical V ck VIVACE System. By introducing passive turbulent control (PTC), the MRELab research team was able to reduce VIV [37,38] and at the same time to initiate galloping, and to achieve back-to-back VIV and galloping on a single circular cylinder [39]. The effects of PTC on multicylinder FIM were further studied experimentally by Kim et al [11] and using CFD by Ding et al [40,41].…”

Surface protrusion based mechanisms of augmenting energy extraction from vibrating cylinders at Reynolds number 3 × 103–3 × 104

“…Their experimental work includes extensive testing of cylinders with distributed sandpaper strips (Passive Turbulence Control/PTC). 4,5,7,11,[17][18][19][20] This approach proved to be effective in augmenting fluid induced motions as they observed galloping oscillations at high reduced velocities. Different types of galloping responses, hard galloping (requiring a threshold amplitude) and soft galloping (not requiring a threshold amplitude), were observed in their experiments depending upon the position of the rough strip.…”

“…One such harvesting device, which falls in the non-rotary class and exploits the phenomena of Fluid Induced Motion (FIM) of bluff bodies (especially Vortex Induced Vibration (VIV) and galloping), is called VIVACE (acronym for VIV for Aquatic Clean Energy) and was developed and patented by Professor Michael Bernitsas and co-workers at the University of Michigan. [4][5][6][7][8][9][10] The device converts the energy of river/tidal/ocean currents to mechanical energy by inducing free vibration of cylinders 6,11 and can be used in water bodies with current velocities as low as 1-2 m/s, as opposed to turbines which operate in currents with velocities > 2 m/s. A VIV based device is simple in construction and is modular, scalable, and robust and does not employ any rotating parts like turbines or propellers.…”