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횡단류 내 평판 위에 놓인 원형 실린더 주위의 유동장 및 열전달에 관한 연구
이기백,손정호,양장식,Lee, Gi-Baek,Son, Jeong-Ho,Yang, Jang-Sik 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.4
The present study is concerned with the heat transfer enhancement associated with a symmetrical or asymmetrical horseshoe vortex in front of and around the circular cylinder centered between the side walls of a wind tunnel. The static pressure measurements and the flow visualization in front of and around cylinders have been performed to determine the existence of horseshoe vortex. The hue-capturing method using the thermochromatic liquid crystals with great spatial resolution was used to obtain the local information of the endwall heat transfer coefficients. In case of one cylinder, the convective heat transfer coefficients of the region where the horseshoe vortex exists are larger than those of any other region. In case of two cylinders with tandem arrangement, the heat transfer rate of gap spacing (d/D= 1.5) is higher than that of gap spacings (d/D=2.0 or 2.5).
색상 포착 기법과 수치계산을 이용한 3차원 밀폐 공간내의 자연대류 연구
이기백,김태영,양장식,Lee, Gi-Baek,Kim, Tae-Yeong,Yang, Jang-Sik 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.12
The natural convection of a horizontal layer heated from below in a three-dimensional rectangular enclosure was dealt with both numerically and experimentally. The aspect ratios are 1:2:3.5 and Boussinesq fluid is water with the Prandtl number of 5.0. This experimental study showed how to measure the variation of temperature field in a 3-D rectangular enclosure with small aspect ratios by using TLC(Thermochromic Liquid Crystal) and color capturing technique. The experimental temperature field had periodic characteristics of 75 sec at Ra=2.37*10$^{5}$ . But the numerical convection flow had periodic characteristics of 79 sec at the same Rayleigh number. In three dimensional computation it was found that the convection roll structure bifurcated from four rolls to two rolls as the Rayleigh number is increased.
와동 발생기 높이 변화에 대한 경계층 내의 유동장과 온도장에 관한 실험적 연구
권수인,양장식,이기백,Gwon, Su-In,Yang, Jang-Sik,Lee, Gi-Baek 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.1
The effects of the interaction between the flow and temperature field and a boundary layer due to a variety of the height of a vortex generator are experimentally investigated. The test facility consists of a boundary-layer wind tunnel with the vortex generator protruding from the bottom surface. In order to control the strength of the longitudinal vortices, the angle of attack and the spacing distance of the vortex generator are 20 degree and 40 mm, respectively. The height of the vortex generator (H) is 15 mm, 20 mm and 30 mm and the cord length of it is 50 mm. Three-component mean velocity measurements are made using a 5-hole probe system and the surface temperature distribution is measured by the hue capturing method using thermochromatic liquid crystals. By using the method mentioned above, the following conclusions are obtained from the present experiment. The boundary layer is thinned in the downwash region where the strong downflow and the lateral outflow of the boundary layer fluid occur and thickened in the upwash re,3ion where the longitudinal vortex sweeps low momentum fluid away from the bottom surface. In case that the height of the vortex generator increases, the averaged circulation and the maximum vorticity of the vortex pair decrease. The contours of the non-dimensional temperature show the similar trends fur all the cases (H=15 mm, 20 mm and 30 mm). The peak augmentation of the distribution of the local non-dimensional temperature occurs in the downwash region near the point of minimum boundary-layer thickness.
이선웅 ( Sunwung Lee ),서영원 ( Yeong-won Seo ),서유진 ( Yu-jin Suh ),이기백 ( Gi-baek Lee ),이영섭 ( Young-sup Lee ) 한국정보처리학회 2017 한국정보처리학회 학술대회논문집 Vol.24 No.2
본 논문에서는 다중의 저가형 단일포인트 라이다와 모터를 결합하여, 고가형 3D 라이다와 유사한 스캐닝 결과를 얻을 수 있는 방법을 고안하였다. 즉, 본 연구에서는 하나의 라이다로 2D 평면을 스캐닝 했을 때의 한계를 보완하는 방법을 제시하고자, 단일포인트 라이다 3 개를 사용하여 3D 공간을 스캐닝 하는 시스템을 구현하였다.