• 한국가시화정보학회:학술대회논문집
• /
• 2003.05a
• /
• pp.47-73
• /
• 2003

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.8
• /
• pp.84-91
• /
• 2005

An experimental investigation has been carried out to examine heat-transfer characteristics of an axisymmetric, under-expanded, sonic jet impinging on a flat plate and the local measurement of surface pressures and heat transfer coefficients on a plate have been achieved together with a visualization test of shock structure in a jet. Heat transfer coefficients on a plate have been found to be changed significantly depending on the under-expansion ratio as much as the nozzle-to-plate distance. These phenomena could be explained by the wall pressure measurement and the shock visualization.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.5
• /
• pp.1737-1746
• /
• 1991

본 연구에서는 저온의 순수물 속의 등온 수직원기둥에 의해 야기되는 열전달 특성을 구명함에 있어서 짧은 원기둥 범주에 속하는 종횡비 0.5인 얼음 원기둥을 이용 하여 실험적으로 열전달 특성을 구명하였다. 그리고 전 유동장을 가시화 하였으며, 얼음의 융해율로써 누셀트(Nusselt)수를 측정하여 기존의 결과들과 비교검토하였다.

• 한국가시화정보학회:학술대회논문집
• /
• 2004.11a
• /
• pp.22-25
• /
• 2004

The present paper investigated the correlation between acoustic pressure and heat transfer augmentation in acoustic fields. The acoustic pressure predicted by numerical work and compared with the augmentation ratio of heat transfer coefficient was experimentally measured. Also, particle image velocimetry(PIV) was used for the visualization of velocity vectors and kinetic energy distribution inside liquid region. For the numerical work, SVS programed with Fortran language and based on a coupled FE-BEM was used. Results of the present study, the acoustic pressure is increased by $60\%$ and the largest augmentation of heat transfer about $28\%$ was measured. Finally, the profiles of acoustic pressure is consistent with that of augmentation of heat transfer. It is concluded that a correlation exists between the acoustic pressure and the heat transfer augmentation.

• Journal of the Korean Society of Visualization
• /
• v.22 no.2
• /
• pp.96-103
• /
• 2024

As micro-electronic devices are getting miniaturized, technology that can manage the temperature of confined area is required. On these demands, microchannel heat exchanger is suggested as promising solution. However, due to laminar flow created inside the microchannel with high Reynolds number suppresses diffusion based natural convection, leads to low heat transfer performance of microchannel. This paper shows how acoustic streaming flow enhances the heat transfer performance inside the microchannel without using additional structure or nanoparticle inside the straight microchannel and fluid numerically. Various parameters, such as Reynolds number (Re), initial displacement (ξ) was adopted to evaluate the influence of acoustic streaming flow. The results showed that acoustic streaming flow can disturb the thermal boundary, by creating the micro-vortex inside the straight-microchannel and enhance the heat transfer performance.

• Journal of the Korean Society of Visualization
• /
• v.3 no.2
• /
• pp.14-20
• /
• 2005

내연기관 연소는 난류유동, 분무, 연소, 열전달의 복합적인 현상으로서 열역학적 해석이 주류를 이루어 왔으나 컴퓨터의 발전에 따라 효율 개선과 공해 저감을 목표로 전산유체해석 기법이 적극적으로 도입되고 있다. 내연 기관 연소의 근간을 형성하는 난류 연소 모델링의 기본 개념으로서 가솔린엔진에서의 예혼합연소와 디젤엔진에서의 확산연소에 대한 영역조건평균(zone conditional averaging) 모델과 조건평균닫힘(conditional moment closure) 모델에 대해 설명하였으며 $NO_x$와 soot 예측에 대한 적용과 엔진응용 사례를 소개하였다.

• Proceedings of the SAREK Conference
• /
• 2004.11a
• /
• pp.16-16
• /
• 2004

• 한국가시화정보학회:학술대회논문집
• /
• 2005.04a
• /
• pp.3-57
• /
• 2005

왕복동 내연기관에서의 연소 및 배기가스 생성은 복잡한 3차원 영역 내에서 난류 유동, 분무, 화학반응, 열전달, 경계층 현상이 상호 연계되어 있는 매우 복합적인 과정이다. 특히 난류 연소 현상은 기관의 효율을 결정하는 연소 속도와 pollutant의 배출 농도를 결정하는 핵심 요소로서 관련 모델과 수치 해법에 대해 학술적, 공학적 측면에서 세계적으로 활발한 연구가 이루어지고 있다. 이를 위해 수행되는 다양한 실험 측정과 수치 해법을 통해 얻어지는 3차원 과도 상태의 방대한 스칼라량과 벡터량에 대한 정보를 효율적으로 처리하기 위해서는 적절한 가시화 과정이 필수적이다. 여기서는 최근 다양한 엔진 타입들에 대한 응용 사례와 함께 난류 연소 모델링을 위한 새로운 접근법으로서 조건평균법(conditional averaging)에 대해 간략히 소개하고자 한다. 난류예혼합연소에서의 난류화염속도에 대한 DNS와 영역조건평균에 기초한 예측식의 검증, 천연가스 jet의 자발화 지연기간, n-heptane jet의 자발화 진행 과정, HSDI 엔진, HCCI 엔진, CNG 엔진, LPG 분무 및 엔진, GDI 엔진 등에 대한 연구 결과들은 정보 가시화의 한 사례가 될 수 있을 것으로 생각된다.

• Journal of the Korean Society of Visualization
• /
• v.20 no.3
• /
• pp.58-66
• /
• 2022

The high heat emitted from the process module and heat jacket may cause errors in semiconductor process equipment. Barriers were designed to reduce the temperature of surface on transfer module. A designed barrier was compared and analyzed by numerical analysis using ANSYS Fluent. The average temperature of barrier and effect of radiation heat transfer were also compared through absorbed radiative heat flux of the barrier. The adoption of the barrier had an effect on the radiative heat transfer reduction of the transfer module rod. The effect of the angles of barrier from 50° to 90° on the heat transfer was investigated using the absorbed radiative heat flux with the average temperature. The angle of barrier of 50° reduced the temperature up to 9.6 %.

• Journal of the Korean Society of Visualization
• /
• v.13 no.3
• /
• pp.24-28
• /
• 2015

The temperature of the wafer batch in the furnace was calculated and its visualized temperature field was analyzed. The main heat transfer mechanisms from the heater wall to the wafers were radiation and conduction, and the finite difference method was used to analyze the complex heat transfer including those two mechanisms. The visualized temperature field shows that the direction of the heat flux in the wafer batch varies during the heating process, and the heat in the wafer batch diffuses faster by conduction within the wafer than by radiation between the wafers, in the condition of the constant temperature at the heater wall and cap.