Wake structures and vortex induced vibration （VIV） of a spring-supported wide-D-section cylinder were experimentally investigated using an X-wire, a novel phase-locked particle image velocimetry （PIV）, and an acce...Wake structures and vortex induced vibration （VIV） of a spring-supported wide-D-section cylinder were experimentally investigated using an X-wire, a novel phase-locked particle image velocimetry （PIV）, and an acceleration sensor at a low speed wind tunnel. Compared with the fixed case, the 2P （two pair） vortex mode as defined by Govardhan and Williamson （2000） rather than S （single vortex） mode exists in the wake. The velocity deficit behind the cylinder is much larger than that of fixed case. The mean drag coefficient increases from 1.42 for the fixed case to 1.64 for the vibrating case. The Reynolds stress presents even distribution and small with increased distance of X/D = -2 to X/D = -10. The power spectra density based on accelerator and hot wire data presents a highlight identical. It shows that after a strong interaction the cylinder vibration and the vortex shedding come to a stable state. The vortex sheddin~ is totally locked on and controlled by the cylinder vihratinn.展开更多
Wake-induced vibration(WIV)is common in engineering and may cause structural damage.The application of bionic devices in vibration control has attracted much attention,but most studies focus on isolated system and pay...Wake-induced vibration(WIV)is common in engineering and may cause structural damage.The application of bionic devices in vibration control has attracted much attention,but most studies focus on isolated system and pay insufficient attention to the response under wake interference,which limits their application in engineering.Therefore,it is crucial to better understand the interaction between flow and bionic devices under wake interference.Inspired by the tail fin structure of fish tail,this paper studies the hydrodynamic characteristics of an elastically mounted cylinder with a tail fin in the wake of an inverted D-section cylinder.By changing the distance between the two centers of the circle and the length of the tail fin,the amplitude,frequency response and the mechanism of wake-induced vibration are explored.The results indicate that as the spacing ratio(L/D)increases,the WIV of the cylinder with a longer tail fin is excited.When WIV occurs,the phase difference(Φ)between the hydrodynamic coefficient and the transverse displacement experiences two jumps,and the lock-in bandwidth is wider compared with the single cylinder.As the tail fin length increases,the transverse lock-in frequency ratio yosu(f_(yosu)/f_(n))decreases.Additionally,vortex shedding from the upstream inverted D-section cylinder(UIDC)affects the surface pressure distribution and vortex shedding characteristics of the downstream cylinder with a tail fin(DCTF).An analysis of the energy transfer reveals that the direction of transmission between the energy transfer and cylinder motion affects the amplitude response.展开更多
基金supported by the National Natural Science Foundation of China(11472158)
文摘Wake structures and vortex induced vibration （VIV） of a spring-supported wide-D-section cylinder were experimentally investigated using an X-wire, a novel phase-locked particle image velocimetry （PIV）, and an acceleration sensor at a low speed wind tunnel. Compared with the fixed case, the 2P （two pair） vortex mode as defined by Govardhan and Williamson （2000） rather than S （single vortex） mode exists in the wake. The velocity deficit behind the cylinder is much larger than that of fixed case. The mean drag coefficient increases from 1.42 for the fixed case to 1.64 for the vibrating case. The Reynolds stress presents even distribution and small with increased distance of X/D = -2 to X/D = -10. The power spectra density based on accelerator and hot wire data presents a highlight identical. It shows that after a strong interaction the cylinder vibration and the vortex shedding come to a stable state. The vortex sheddin~ is totally locked on and controlled by the cylinder vihratinn.
基金supported by the National Natural Science Foundation of China(Grant No.52277227).
文摘Wake-induced vibration(WIV)is common in engineering and may cause structural damage.The application of bionic devices in vibration control has attracted much attention,but most studies focus on isolated system and pay insufficient attention to the response under wake interference,which limits their application in engineering.Therefore,it is crucial to better understand the interaction between flow and bionic devices under wake interference.Inspired by the tail fin structure of fish tail,this paper studies the hydrodynamic characteristics of an elastically mounted cylinder with a tail fin in the wake of an inverted D-section cylinder.By changing the distance between the two centers of the circle and the length of the tail fin,the amplitude,frequency response and the mechanism of wake-induced vibration are explored.The results indicate that as the spacing ratio(L/D)increases,the WIV of the cylinder with a longer tail fin is excited.When WIV occurs,the phase difference(Φ)between the hydrodynamic coefficient and the transverse displacement experiences two jumps,and the lock-in bandwidth is wider compared with the single cylinder.As the tail fin length increases,the transverse lock-in frequency ratio yosu(f_(yosu)/f_(n))decreases.Additionally,vortex shedding from the upstream inverted D-section cylinder(UIDC)affects the surface pressure distribution and vortex shedding characteristics of the downstream cylinder with a tail fin(DCTF).An analysis of the energy transfer reveals that the direction of transmission between the energy transfer and cylinder motion affects the amplitude response.
