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Measurement of Turbulent Intensity Distributions of a Cylinder Wake
Doh, Deog Hee,Cho, Gyeong Rae,Moon, Kyeong Rok,Cho, Yong Beom The Korean Society of Visualization 2013 한국가시화정보학회지 Vol.11 No.1
Turbulence properties of a cylinder wake (d=10 mm) have been investigated with a new volume PTV algorithm. The measurement system consists of two-high-cameras(1 $k{\times}1$ k), a Nd-Yag laser and a host computer. A fitness function representing three-dimensional coherency has been adopted to sort out spurious vectors. A hybrid fitness function representing the relations between the fitness and the three-dimensional shortest distances constructed by the two collinears of the two cameras has been also adopted. The constructed algorithm has been employed for the measurements of the cylinder wakes. The Reynolds numbers tested in this paper are 360, 540, 720, 900, 1080 and 1260. More than 10,000 instantaneous 3D vectors have been obtained by the constructed system. The volumetric distributions of the turbulence intensities (for u', v', w') indicate that clearly different patterns for all Reynolds numbers and imply that a regular pattern (like a similarity rule) for the turbulent properties exists.
Deog Hee Doh,Masahiro Takei,Kenji Tanaka 한국가시화정보학회 2006 KOREA-JAPAN Joint Seminar on Particle Image Veloci Vol.- No.-
An adaptive stereoscopic-PIV system has been constructed for flow analyses around a cylinder body. The body is floated by the swirling flows in a vertical pipe with a length of 600mm and an inner diameter of 100㎜. Four optical sensors(LEDs) were installed onto the pipe wall to detect the posture of the cylinder body. The constructed stereoscopic-PIV system is activated by the signals of the optical sensors when the cylinder is in upright posture. The measurement system consists of two cameras, a Nd-Yag laser and a host computer. Flow characteristics around the floating cylinder body and the motional characteristics of the body itself are investigated when the body becomes upright posture. It has been verified that the motion of the floating cylinder becomes stable when the azimuthal velocity component of the swirl flow is maintained at stable states.
Deog Hee Doh,Koji OKAMOTO 한국가시화정보학회 2004 KOREA-JAPAN Joint Seminar on Particle Image Veloci Vol.- No.-
A 4D-PIV system was constructed. The measurement system consists of three high-speed high-definition cameras(1k × 1k, 2000fps), Nd-Yag laser(2000Hz) and a host computer. The GA-3D-PIV algorithm was used for completing the measurement system. The 4D-PIV is capable of probing the spatial distribution of velocity vectors of the flow field overcoming the temporal resolution of the characteristic turbulence length scales of the measured flow fields. A horizontal impinged jet flow (H/D=7) was measured. The Reynolds number is about 33,000. Spatial temporal evolution of the jet flow was examined and physical properties such as spatial distributions of vorticity and turbulent kinetic energy were obtained with the constructed.