000004959 001__ 4959
000004959 005__ 20141119144608.0
000004959 04107 $$aeng
000004959 046__ $$k2002-06-02
000004959 100__ $$aKeles, Resat S.
000004959 24500 $$aACTIVE CONTROL OF VORTEX SHEDDING IN THE FAR WAKE OF A CYLINDER

000004959 24630 $$n15.$$pProceedings of the 15th ASCE Engineering Mechanics Division Conference
000004959 260__ $$bColumbia University in the City of New York
000004959 506__ $$arestricted
000004959 520__ $$2eng$$aIn this paper, some preliminary results reported from experimental observations of two-dimensional air flows with a Reynolds number of 170 passing a stationary circular cylinder and its active control achieved in the far wake. The free stream velocity of the wind tunnel maintained uniformly at U∞=80.4 cm/sec during the experiment. The amplitude of velocity fluctuations measured vertically above the cylinder centerline with a hot-wire probe positioned at a streamwise station of x/d=7 (far wake) on center under natural and control conditions of the transitional flow in the wake of the cylinder. The feedback hot-wire sensor was located in the upper shear layer of the cylinder at about 0.9d streamwise and about 0.8d above the cylinder axis. After the phase of the feedback signal shifted 180˚±2˚ and the amplifier gain adjusted, perturbations imposed at vortex-shedding frequency on the wake of the cylinder on both sides of the wind tunnel. The induced perturbations were significant and the Karman vortex street responded vigorously to the feedback of the signal from the hot-wire sensor in the wake of the cylinder at vortex-shedding frequency. The power spectrum of turbulence velocity fluctuations significantly reduced at Strouhal frequency. This is interpreted as the control of vortex shedding achieved in the far wake of a cylinder. Thereafter, the amplitudes of velocity fluctuations were significantly reduced in the Karman vortex street. In this experiment, we have been able to demonstrate the active of vortex shedding in the beginning of the far wake distance x/d=7 of the cylinder-wake at Strouhal vortex shedding frequency, However, shedding of the vortices in the wake not controllable at distance x/d = 20 and further downstream. 

000004959 540__ $$aText je chráněný podle autorského zákona č. 121/2000 Sb.
000004959 653__ $$aActive Control of Vortex Shedding, Bluff-Body Wake Control, Drag Reduction, Fluid-Structure Interaction.

000004959 7112_ $$a15th ASCE Engineering Mechanics Division Conference$$cNew York (US)$$d2002-06-02 / 2002-06-05$$gEM2002
000004959 720__ $$aKeles, Resat S.
000004959 8560_ $$ffischerc@itam.cas.cz
000004959 8564_ $$s253835$$uhttp://invenio.itam.cas.cz/record/4959/files/617.pdf$$yOriginal version of the author's contribution as presented on CD, .
000004959 962__ $$r4594
000004959 980__ $$aPAPER