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정의엽(Eui Yeop Jung),정희윤(Heeyoon Chung),박세진(Sehjin Park),조형희(Hyung Hee Cho) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
In the present study, total cooling effectiveness was obtained by experiment method on a full-coverage film cooling plate. To confirm the conduction effect of film cooling plate, we conducted three experimental cases. These cases used three different conductive materials, which were polycarbonate, Corian, and stainless steel. The test plates had same hole pattern in the three experiment cases. The hole diameter was 5 mm and the angle of film cooling hole was 35 degree. Spacing to hole diameter ratio (p/d) was 3 on the film cooled plate in both the streamwise and spanwise direction. The jet Reynolds number was controlled to 7,000. The detailed temperature distribution on the film cooled surface was measured using the infra-red thermographic technique. Total cooling effectiveness increased with thermal conductivity of film cooling plate. We demonstrated adiabatic film cooling effectiveness for using this research results.
다열 충돌유출 냉각의 Biot 수에 따른 냉각 성능 평가
정의엽(Eui Yeop Jung),김정주(JeongJu Kim),김상제(Sangjae Kim),박철(Chul Park),김용진(YongJin Kim),조형희(Hyung Hee Cho) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
Cooling performance was determined on a film cooled surface with staggered array jet impingement cooling at various Biot numbers. Heat transfer experiments were conducted using infra-red thermography. Conjugated heat transfer was analyzed with the combined effects of conduction through the test plates and convective heat transfer due to the arrayed jet impingement. The angle of the film cooling holes was 35° and that of the jet impingement holes was 90°. The film and jet impingement holes on each plate were arranged in staggered patterns, and the film cooling holes and jet impingement holes were also positioned in a staggered pattern. The distance between jet and film hole plates was fixed. When jet impingement was added to the internal cooling, the averaged total cooling effectiveness was enhanced. At low Biot numbers, meaning that cooling performance dominated over the conduction effect, the temperature distribution became more uniform due to higher conductive heat transfer. The total cooling effectiveness was strongly related to the Biot number of the plate, and comparing the existing 1-D conduction analysis with the experimental results to predict the total cooling effectiveness in an actual gas turbine engine.
90도 곡관 내부의 유동가속부식을 저감시키기 위한 구조물 삽입에 대한 연구
정의엽(Eui Yeop Jung),최석민(Seok Min Choi),김선호(Seon Ho Kim),김경민(Kyung Min Kim),조형희(Hyung Hee Cho) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
In the HRSG system, pipe components made of carbon steel are exposed to forced flow. The flow accelerated corrosion by forced flow results in wall thinning, and generates pipe thinning. The rate of wall thinning is related to the mass transfer coefficient in the internal surface of pipe. Thus it is necessary to reduce the mass transfer coefficient for prevention of pipe rupture. In the pipe of 90 degree, the maximum mass transfer coefficient is located at the downstream of turning region by dean vortices. This study focused to investigate the reduced dean vortex using A-shape ribs. Numerical analysis was performed to obtain the mass transfer coefficient using commercial code. Flow velocity was 1.5m/s, and working fluid was water. Based on the comparison of the results, the mass transfer coefficient in the pipe of 90 degree with A-shape ribs reduced at the downstream region of turning part compared to that of smooth pipe due to removal dean vortices.