Energy Extraction From FIV Of Different Diameter Cylinders And Water Tunnel Documentation

With the needs of social and economic development and environmental protection,people are paying more and more attention to renewable resources such as wind energy,tidal energy and ocean current energy.In recent years,due to the rapid development in the field of renewable energy,power extraction devices based on flow-induced vibration(FIV)have continuously emerged,and a lot of researches on fluid-induced vibration and its energy extraction have been conducted.However,current power generation with a bluff body only extract low bandwidth vortex-induced vibration(VIV)based energy within a low specified flow velocity range.Considering the higher energy galloping caused by tandem cylinders of different diameters,it is expected to develop a new type of energy extraction device.The energy harvesting from FIV of an elastically-supported cylinder(diameter D)immersed in the wake of another cylinder with diameter d was investigated.The diameter ratio of the two cylinders was d/D = 0.4.The incoming flow velocity considered was U_? = 1.54 m/s ? 9.0 m/s,corresponding to Re = 3.3 × 10~3 ? 1.95 × 10~4.A controllable magnetic damping system that can add harnessing damping ratio was used to convert wind energy to electrical energy.The ? was varied from 0.00091 to 0.00340.Seven spacing ratios L/d = 1.0,1.5,2.0,2.5,3.0,3.5,and 4.0 were considered,where L was the distance between the cylinders.Based on the vibration responses of the cylinder,the power P and efficiency ? of the energy harvesting were optimized.As the experimental results show,the vibration responses comprised combined VIV and galloping for small ? and separated VIV and galloping for high ?.With ? increasing,the band-width of VIV and critical reduced velocity of galloping onset declined.The galloping offered harnessed power P three times larger than the VIV.The efficiency ? was 19% ? 28.5%(maximum)in the VIV regime while almost independent of U_r and ? in the galloping regime,maximum ? being 2% ? 5%.This paper also carried out the documentation of the horizontal water tunnel,using various measurement methods to test the water tunnel accurately.