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박승덕(Seoung Duck Park),이기선(Ki Seon Lee),곽재수(Jae Su Kwak),전용민(Youngmin Jun),황인희(Inhee Hwang) 한국유체기계학회 2008 유체기계 연구개발 발표회 논문집 Vol.2008 No.-
In this paper. the detailed heat transfer coefficient on a rotating dimpled channel were measured using the transient liquid crystal technique. The channel height to dimple diameter was 2. dimple center distance to dimple diameter was 1.5 and channel aspect ratio was 4. Tested Reynolds number based on the channel hydraulic diameter was varied from 15000 to 35000 and corresponding rotation number was ranged from 2.31 to 1.16. Results showed that the Coriolis force by rotation enhanced the heat transfer coefficient on the trailing surface. As the Reynolds number increased, i.e. rotation number decreased, the heat transfer coefficient increased and the the thermal performance factor decreased.
반복된 제트 충돌을 갖는 내부 유로의 평균 열전달 계수 측정
박승덕,이기선,김석범,조용화,전창수,곽재수,허재성,Park, Seoung Duck,Lee, Ki Seon,Kim, Sug Bum,Jo, Yong Hwa,Jeon, Chang Soo,Kwak, Jea Su,Huh, Jae-Sung 항공우주시스템공학회 2008 항공우주시스템공학회지 Vol.2 No.4
Averaged heat transfer coefficients were measured in a turbine blade internal cooling passage model with three blockage walls. Each blockage wall was equipped with 9 staggered holes or slots in order to create different shaper of repeated jet impingement. The effect of jet shape on the averaged heat transfer coefficient was studied by the copper-thermocouple method and three Reynolds number of 10,000, 20,000, and 30,000 were tested. Results showed that the repeated stagger jets could increase the averaged heat transfer coefficient by at least 9 times compared to the smooth channel cases. Due to the large pressure drop induced by the repeated jet impingement, the thermal performance was less than 1 for all cases and decreased as the Reynolds number increased. Among the tested cases, the widest slot showed the best thermal performance. The measurement results showed that the thermal performance of the heat transfer augmentation by repeated stagger jets could be improved by altering the jet shape, and other shape of impingement jet will be studied in near future.
터빈 블레이드 팁 형상과 간극 크기에 따른 전압 손실 연구
이기선(Ki Seon Lee),박승덕(Seoung Duck Park),노영철(Young Chul Noh),곽재수(Jae Su Kwak),전용민(Yongmin Jun) 한국유체기계학회 2008 유체기계 연구개발 발표회 논문집 Vol.2008 No.-
Leakage (Jaw through turbine blade tip gap causes strong leakage vortex on the blade suction side and induces large aerodynamic losses. In this study. The conventional plane tip and various squealer tip blades wore tested in a linear cascade in order to measure the effect of the tip shape on the aerodynamic loss by the tip leakage vortex Three tip gap clearances of 0.6%. 1.39'c. and 2.0% of blade span were tested. Flow measurement was conducted at one chord downstream from the trailing edge with five-hole probe. Results showed that the leakage vortex was stronger than passage vortex and the mass averaged overall total pressure loss through the cascade was the lowest for suction side tip compared to other tested tip cases. For all tested cases. the mass averaged overall total pressure loss was higher at 1.3% of tip gap clearance.
이중 충돌 제트를 갖는 사각 덕트 내의 열전달 계수 측정
신소민(Somin Shin),이기선(Ki Seon Lee),박승덕(Seoung Duck Park),곽재수(Jae Su Kwak),차봉준(Bong Jun Cha) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Heat transfer coefficients were measured by the improved hue detection based on liquid crystals technique in a turbine blade internal cooling passage model with three blockage walls. In the experiments, blockages with 9 holes of circular, wide, narrow shapes were used and for the circular shapes, holes number of 7, 9, and 11 were tested. For all cases, the total perforated area was kept same. Results showed that the staggered impingement jets increased heat transfer coefficient, however, pressure drop also increased greatly. Generally, Nusselt number ratio and the thermal performance factor decreased as Reynolds number increased. For all Reynolds numbers tested, the blockage wall with wide holes gave more uniform heat transfer coefficient and higher thermal performance factor. As the number of hole increased from 7 to 11, the distribution of heat transfer coefficient became uniform and the thermal performance factor increased.