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단일 카메라 입자영상유속계를 이용한 이상유동 기포율 측정방법
최동환(Dong Whan Choi),성재용(Jaeyong Sung),유정열(Jung Yul Yoo) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
A measurement technique for the void fraction and the bubble dynamics in gas-liquid two-phase flows has been proposed using a time-resolved two-phase PIV system. For the three-dimensional evaluation of the bubble information, both the images from the front and side views are simultaneously recorded into a high speed CCD camera by reflecting the side image into the front view with the help of a 45° oriented mirror. Then, a stereo-matching technique is applied to calculate the void fraction, bubble size and shape. To obtain the rising bubble velocities, the 2-frame PTV method was applied. Consequently, the present technique shows good feasibility for the measurements of the volume fractions, mean diameters, aspect ratios and velocities of the bubbles at the three-dimensional point of view.
단일 카메라를 이용한 이상유동 기포율 측정방법의 개발과 응용
최동환(Dong whan Choi),성재용(Jae yong Sung),유정열(Jung Yul Yoo),송진호(Jin Ho Song) 대한기계학회 2007 大韓機械學會論文集B Vol.31 No.11
A measurement technique for void fraction has been proposed using a time-resolved two-phase PIV system and the bubble dynamics has been investigated in gas-liquid two-phase flows. For the threedimensional evaluation of the bubble information, both the images from the front and side views are simultaneously recorded into a high speed CCD camera by reflecting the side view image on a 45° oriented mirror to be juxtaposed with the front view image. Then, a stereo-matching technique is applied to calculate the void fraction, bubble size and shape. To obtain the rising bubble velocities, the 2-frame PTV method was adopted. The present technique is applied to freely rising bubby flows in stagnant liquid. The results show that the increase of bubble flow rate gives rise to the increase of bubble size and rising velocity at first. If it goes over a certain level, the rising velocity becomes constant and the horizontal velocity grows bigger instead due to the obstruction of other bubbles.
장진성,성형건,이상복,노태성,최동환,Jang, Jin-Sung,Sung, Hyung-Gun,Lee, Sang-Bok,Roh, Tae-Seong,Choi, Dong-Whan 한국군사과학기술학회 2011 한국군사과학기술학회지 Vol.14 No.1
Using the numerical code for the interior ballistics, the performance of the interior ballistics with the characteristic of the ignition-gas injections has been investigated. The ignition gas has been assumed to be injected into the chamber with 3 cases. As the results of analysis, when the ignition-gas has been injected into all chamber area, the pressure distributions of the chamber of the interior ballistics have been uniform and the differential pressure has been stable. The ignition-gas has been injected into the partial area of the chamber, however, the pressure distributions and the differential pressure have been unstable. The case using the longer ignition injector, therefore, seems to be more suitable to improve the stability of the interior ballistics.