형상법칙을 이용한 트리구조의 압력강하 최적화 연구

조기현(Kee-Hyeon Cho),이재달(Jae-Dal Lee),김무환(Moo-Hwan Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

An analytical study was carried out on the flow resistance of tree-shaped channel flow architectures, based on the principle of the constructal law of evolutionary increase of flow access through the generation of better flowing configurations with two diameters in the square domain. Two types of tree-shaped configurations are optimized. The minimized global flow resistance decreases definitely as the system size, N, increases. And the best channel configurations among the first construct and second construct as a result of regarding pressure drop was selected. We also show that the freedom to morph the design and to increase its performance can be enhanced by using treetree configurations with 2<SUP>nd</SUP> construct when N is greater than 18.

냉각채널 형상변화에 따른 유동 및 열저항 최적화 연구

조기현(Kee-Hyeon Cho),안호선(Ho Seon Ahn),김무환(Moo-Hwan Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

In this study, we investigated the hydrodynamic and thermal performance of constructal architectures based on the mass flow rates for the given pressure drop and identify the required pumping power and thermal resistance. The five flow configurations described in this paper are the first, second constructs with optimized hydraulic diameters and nonoptimized hydraulic diameter, respectively, including the serpentine configuration. The results suggest that best fluid flow structure is the second constructal structure with optimized constructal configurations. We also found that the optimized structure of cooling plates could enhance heat transfer remarkably and decrease pumping power dramatically compared with the traditional channels.

냉각유로 형상변화에 따른 유동 및 열저항 최적화 연구

조기현(Kee-Hyeon Cho),안호선(Ho-Seon Ahn),김무환(Moo-Hwan Kim) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.1

본 연구에서는 3 차원 전산 열유동해석을 통하여 형상법칙에 근거하여 개발된 냉각판의 열수력학적인 특성을 분석하였다. 서펜타인 형상을 포함하여 최적화, 최적화되지 않은 1, 2 차 형상 총 5 개 형상을 대상으로 동일한 구속조건을 부여함으로써 유동저항, 열저항 및 분지유로에서의 유동균일도를 상호 비교함으로써 냉각판의 성능평가를 수행하였다. 그 결과, 최적화된 1, 2 차 형상 구조가 최적화되지 않은 경우와 비교하여 훨씬 적은 압력손실을 나타내었으며, 압력손실을 기준으로 최적화된 2 차 형상 구조가 가장 우수한 유동 구조를 나타내었다. 또한, 최적화된 1, 2 차 형상구조의 열저항 및 유동 분배성능도 기존에 사용되는 유로형상과 비교하여 모두 우수한 성능을 보였다. In this study, we investigated the hydrodynamic and thermal performance of constructal architectures on the basis of the mass flow rates for a given pressure drop, and we determined the thermal resistance and flow uniformity. The five flow configuration used in this study were the first construct with optimized hydraulic diameter, the second construct with optimized hydraulic diameter, the first construct with non-optimized hydraulic diameter, second construct with non-optimized hydraulic diameter, and a serpentine configuration. The results of our study suggest that the best fluid-flow structure is the second constructal structure with optimized constructal configurations. We also found that in the case of the optimized structure of cooling plates, the heat transfer was remarkably higher and the pumping power was significantly lower than those of traditional channels.

형상법칙을 이용한 트리구조의 압력강하 최적화 연구

조기현(Kee-Hyeon Cho),이재달(Jae-Dal Lee),김무환(Moo-Hwan Kim) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.1

트리구조의 채널형태를 갖는 정방형 냉각판을 대상으로 형상법칙에 근거하여 유동저항이 최소화된 채널구조를 해석적인 방법으로 도출하였다. 두 가지 (1차, 2차) 형상 의 트리구조에 대해서 유동저항최적화를 수행한 결과, 시스템 크기가 증가할수록 최소화된 무차원 유동저항은 전반적으로 감소하는 경향을 보였다. 또한, 1차, 2차 형상모델 중 압력강하를 기준으로 성능을 판단할 경우, 시스템 크기가 18² 보다 큰 경우에는 차 형상보다는 차 형상이 우수한 결과를 나타내었다. An analytical study on the flow resistance of tree-shaped channel-flow architectures was carried out based on the principle of the constructal law; the evolutionary increase in the access to currents that flow through the channels with improvements in the flow configurations were studied in a square domain using two diameters. Two types of tree-shaped configurations were optimized. The minimized global flow resistance decreased steadily as the system size N² increased. From the two channel configurations, the one that resulted in better pressure drop was selected. Further, it was shown that the system performance can be enhanced by adopting the second tree-shaped configurations when the system size is greater than 18².

혈관구조의 냉각판 성능에 관한 해석적/수치해석적/실험적 비교

조기현(Kee-Hyeon Cho),김무환(Moo-Hwan Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5

해석적, 수치해석적, 실험적인 방법을 통하여 반원형상의 채널로 구성된 냉각판의 열수력학적인 특성을 고찰하였다. 본 연구에서는 레이놀즈 수 30-2000, 그에 따른 냉각판의 압력손실 30-10? ㎩의 구간에서 수행되었으며, 냉각채널 부피비 0.04, 시스템 크기 10 × 10, 20 × 20 및 50 × 50 각각에 대하여 최적화 및 최적화되지 않은 1, 2, 3차 형상 6개가 포함되었다. 해석적 방법으로 설계된 혈관구조 설계를 검증하기 위하여 3차원 수치해석이 수행되었다. 또한, 실험데이타를 통하여 수치해석모델에 대한 타당성이 검증되었으며, 모든 경우에 있어서 수치해석 및 실험결과가 비교적 잘 일치된 경향을 나타내었다. 또한, 최적화된 냉각판의 유동저항 및 열저항 모두 최적화되지 않은 냉각판에 비하여 뚜렷하게 작게 나타났으며, 제시된 수치해석 모델 역시 모두 냉각판의 성능예측에 유용한 도구임이 검증되었다. Analytical, numerical and experimental analyses were conducted to investigate hydraulic and thermal performance of new vascular channels, whose cross-sections had a semi-circular shape. The current work covered the Reynolds number range of 30-2000, cooling channels volume fraction of 0.04, pressure drop range of 30-10? ㎩, and six flow configurations: first, second, and third constructal structures with optimized hydraulic diameters and non-optimized hydraulic diameter for each system size 10 × 10, 20 × 20, and 50 × 50, respectively. To validate our vascular designs by an analytical approach, three-dimensional numerical works were performed. The numerical model was also validated by experimental data, and the comparison results exhibited an excellent agreement in all cases. The validation study against the experimental data showed that the optimized structure of cooling plates could enhance heat transfer significant1y and decrease pumping power dramatically, compared with traditional channels. It was also shown that the numerical model presented proves to be a reliable tool for predicting the performance of cooling plates under practical operating conditions.

반원형 구조의 냉각판 성능에 관한 해석적/수치해석적/실험적 비교

조기현(Kee-Hyeon Cho),김무환(Moo-Hwan Kim) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.12

해석적, 수치해석적, 실험적인 방법을 통하여 반원형상의 채널로 구성된 냉각판의 열수력학적인 특성을 고찰하였다. 본 연구에서는 레이놀즈 수 30-2000, 그에 따른 냉각판의 압력손실 30-10? Pa 의 구간에서 수행되었으며, 냉각채널 부피비 0.04, 시스템 크기 10 × 10, 20 × 20 및 50 × 50 각각에 대하여 최적화 및 최적화되지 않은 1, 2, 3 차 형상 6 개가 포함되었다. 해석적 방법으로 설계된 혈관구조 설계를 검증하기 위하여 3 차원 수치해석이 수행되었으며, 실험을 통하여 수치해석모델에 대한 타당성이 검증되었고, 전 범위에 걸쳐서 수치해석 및 실험결과가 비교적 잘 일치된 경향을 나타내었다. 또한, 최적화된 냉각판의 유동저항 및 열저항 모두 최적화되지 않은 냉각판에 비하여 뚜렷하게 작게 나타났으며, 제시된 수치해석 모델 역시 모두 냉각판의 성능예측에 유용한 도구임이 확인되었다. An analytical, numerical, and experimental comparison of the hydraulic and thermal performance of new vascular channels with semicircular cross sections was conducted. The following conditions were employed in the study: Reynolds number, 30?2000; cooling channels with a volume fraction of the cooling channels, 0.04; and pressure drop, 30?10? Pa. Three flow configurations were considered: first, second, and third constructal structures with diameters optimized for hydraulic operations. To validate the proposed vascular designs by an analytical approach, 3-D numerical analysis was performed. The numerical model was also validated by the experimental data, and the comparison results were in excellent agreement in all cases. The validation study against the experimental data showed that compared to traditional channels, the optimized structure of the cooling plates could significantly enhance heat transfer and decrease pumping power.

연주주편 내부품질 확보를 위한 미응고 압하기술

강기판(kang Gi Pan),조기현(Cho Kee Hyeon),정영진(Jung Young Jin) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

Liquid core reduction (LCR) means the technology that upper frame of bender semgent press the solified shell of slab in the strand of caster. Thus, bender segment frame should have the sufficient strength against the pressing force. We have designed the bender segment and conducted experiments on several cases according to slab thickness. And then, we have obtained the material property of the range 900~1300℃ through the compression test in high temperature furnace. We have also done the LCR test in the pilot caster and compared with the result of compression test. And then, we have found that there is an analogy between LCR force and the compression strain curve in high temperature. As a result, we have known that the inner quality of slab is secured under the 20% over pressing condition of slab thickness.