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도덕희(D.H. Doh),조효제(H.J. Jo),조경래(K.R. Cho),문경록(K.R. Moon),이재민(J.M. Lee),황태규(T.G. Hwang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
A new 3D-PTV algorithm (a Volume PTV) based upon a hybrid fitness function has been constructed. A coherency fitness function is introduced using the information of space and time to sort out the correct particle pairs between the two camera images. The measurement system consists of two-high-definition-cameras(1k × 1k), a Nd-Yag laser and a host computer. The developed algorithm has been employed to investigate the flow features of the cylinder wake. The Reynolds numbers with the cylinder diameter (d=10㎜) are 360, 720, 900 and 1260. Two-dimensional displacements of the particles of each camera’s image and neighbouring constraints were introduced to reduce the calculation loads. More than 10,000 instantaneous 3D vectors have been obtained by the constructed algorithm. The constructed algorithm could recover more than 80~90% of the particle numbers in the image.
문경록(K. R. Moon),도덕희(D.H. Doh),조효제(H.J. Jo),조경래(G.R. Cho),김병열(B.Y. Kim),황태규(T.G. Hwang) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The wakes of a cylindrical body upon which a flexible plate has been attached have been investigated. The plate is made of silicon with configurations of 50㎜(W) × 150㎜(L) × 0.3㎜(T). The cylinder wakes have been tested with PIV experiments under the conditions with and without the flexible plate. The diameter of the installed cylinder body is 30㎜ and the Reynolds numbers are 2730, 6160 and 9750 wi th the diameter. The measurement system consists of an Ar-ion laser(6W), a high speed camera(1024 × 992 pixel, 500fps) and a host computer. FFT analyses have been carried out using the velocity vectors obtained by PIV measurements at the point X/D=1.52 and Z/D=0.52. It has been verified that the flexible plate suppresses or damps the vortices separated from the cylinder body, which makes the cylinder's wakes stable. With increase of Re numbers the intensity of the dominant frequency of the wakes become smaller.
도덕희(Doh D.H),조효제(Jo H.J),황태규(Hwang T.G),조경래(Cho K.R),편용범(Pyeon Y.B),조용범(Cho Y.B) 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-
Experimental analyses on the Hrdroelastic Flow-Structure Interactions on pulsed impinged jet is measured with the FSIMS(Flow-Structure Interaction Measurement System. The nozzle diameter is D=15㎜ and two major experiments have been carried out for the cases of the distance between the nozzle tip to the elastic wall is 6.0. The pulsed jets were controlled by a solenoid valve and were impinged onto an elastic plate (material: silicon, diameter: 350㎜, thickness: 0.5㎜, hardness: 15). The Reynolds numbers were 20,000 and 24,000 when the jets were impinged with the volume velocities. The results showed that the elastic plate moved slightly to the opposite direction of the jet direction at the time of valve opening. It has been shown that the vortices travelling over the surface of the wall made the elastic wall distorted locally due to a vector forces between rotating forces of the vortex and a newly-incoming flow.