초록 ▼

1. 연구개발목표 및 내용
어떤 복잡한 난류 열유동도 해석할 수 있는 세계 최고 수준의 첨단 유동가시화 기술들을 개발하고, 그 정확성과 유용성을 검증한다. 그리고 이들 측정 및 해석기술들을 복잡한 난류전단유동에 적용하여 지금까지 밝히지 못했던 난류 열유동의 3차원 유동구조나 전열특성을 정확하게 해석하고자 함
1) 첨단 속도장 측정기법의 개발과 복잡한 3차원 난류유동의 해석
2) 첨단 온도장/압력장 측정기법의 개발 : 기존의 점측정 방식을 대체할 새로운 측정기법 개발
3) 첨단 유동가시화 기법의 응용 :

1. 연구개발목표 및 내용
어떤 복잡한 난류 열유동도 해석할 수 있는 세계 최고 수준의 첨단 유동가시화 기술들을 개발하고, 그 정확성과 유용성을 검증한다. 그리고 이들 측정 및 해석기술들을 복잡한 난류전단유동에 적용하여 지금까지 밝히지 못했던 난류 열유동의 3차원 유동구조나 전열특성을 정확하게 해석하고자 함
1) 첨단 속도장 측정기법의 개발과 복잡한 3차원 난류유동의 해석
2) 첨단 온도장/압력장 측정기법의 개발 : 기존의 점측정 방식을 대체할 새로운 측정기법 개발
3) 첨단 유동가시화 기법의 응용 : 난류 열유동(난류경계층 유동, 물체 후류 유동, 비등온 제트 유동, 선체 주위 3차원 유동, fan 및 프로펠러 주위 회전유동 등), 수력학, 미세유동, 생체유동 등에 적용하여 주어진 열유동의 속도장과 온도장 등에 대한 유동정보를 얻고, 이들 열유동을 정확히 해석함.
2. 연구결과
1) 첨단 속도장 측정기법의 개발
- Hycrid PTV 속도장 측정기법의 개발
- Stereoscopic PIV (SPIV) 속도장 측정기법의 개발
- SPIV와 hybrid PTV를 결합한 stereoscopic PTV기법의 개발
- CBC(correlation based correction) 방식의 recursive PIV기법 개발
- Holographic PIV(HPIV) 속도장 측정기법의 개발
- PIV/PTV 프로그램의 GU化 (Visual PIV, Visual PTV)
- Dynamic PIV 시스템 구축
- 난류구조 해석을 위한 POD 해석 기법의 개발
- Micro-PIV 속도장 측정기법의 개발
- X-ray micro-imaging기술을 이용한 X-ray PIV기법의 개발
- X-ray 미세영상기법을 이용한 미세기포의 속도 및 크기 동시 측정기술 개발
2) 첨단 온도장/압력장 측정기법의 개발
- LIF 온도장 측정기법의 개발
- Holographic interferometer 시스템 구축
- Holographic 간섭계와 PIV기법을 이용한 온도장과 속도장 계측기술
- Dual-emission방식의 two-color LIF기법 개발
- 아음속 유동에 적합한 PSP 압력장 측정기법의 개발
3) 첨단 유동가시화기법의 응용 연구
- 복잡한 난류전단유동(경계층, 제트, 후류) 연구
- 프로펠러와 선체주위 유동연구
- Micro-riblet이나 O-ring이 부착된 원주후류 연구
- Micro-riblet이 부착된 익형주위 유동 연구
- SPIV 측정기법으로 타원제트의 유동특성과 유입률해석
- 선박 프로펠러 주위 유동 해석
- 회전하는 프로펠러가 달린 컨테이너 선박주위 유동 해석
- Sinusoidal 형상의 원주 후류 해석
- 주기적으로 회전 진동하는 원주후류 유동 해석
- 삼각형 탭과 mesh screen이 충동분류 열전달 향상에 미치는 영향 연구
- 자유표면과 물체사이의 상호작용 연구
- 증발기표 내부 유동특성 해석
- Micro-PIV로 마이크로채널의 입구형상과 electro-kinetic 효과
- X-ray micro-imaging 기술을 이용한 생체 내부 유동가시화
- X-ray PIV로 미세관 내부 혈액유동과 식물 내부 수액거동 해석
- 컨테이너선 주위 유동 해석
- 공장이나 자동차 내부 환기유동 해석
3. 기대효과 및 활용방안
1) 기존에 밝혀내지 못하였던 유동구조나 열전단 특성을 해석할 수 있으며, 에너지와 환경과 같은 공공부문의 열유동 문제에 능동적으로 대처하는데 필요한 핵심기반기술의 확보
2) 개발된 첨단 유동가시화 기술들을 운송체나 물체 주위 유동, 유체기계 유동, 환경공학분야, 그리고 냉동과 공기조화 분야 등의 열유동 문제해결에 활용
3) 혈관 유동과 bio-chip과 같은 생체유체분야의 미세유동이나 생체유동에의 응용
4) 첨단 가시화기술과 해석기술들을 세미나와 단기강좌 등을 통해 기술지도 및 기술이전

Abstract ▼

Human life is intimately related to unsteady turbulent, non -isothermal flows which occur in nature and industrial applications. The demands for saving energy with improved efficiency of thermo-fluid products and for decreasing environmental pollutions are ever increasing. This requires accurate pre

Human life is intimately related to unsteady turbulent, non -isothermal flows which occur in nature and industrial applications. The demands for saving energy with improved efficiency of thermo-fluid products and for decreasing environmental pollutions are ever increasing. This requires accurate prediction and effective control of turbulent thermo-fluid flows. In order to fully understand and control the flow effectively, it is important to get accurate information on the velocity and temperature distributions of the flow. Due to rapid advances in the computer and digital image processing techniques, it is now possible to measure the spatial distributions of instantaneous velocity and temperature fields as well as the turbulent structures by ensemble averaging the sequential velocity and temperature field data. It is an essential core technology for the diagnosis of thermo-fluid flow problems involving with various fields such as mechanical engineering, aerospace, ship and ocean engineering, energy, environmental and civil engineering, electronics and bio-technology etc.

The objective of this research project is to develop the most advanced flow visualization techniques which can analyze complicated thermo-fluid flows accurately and then to apply to various turbulent thermo-fluid flows to reveal the hitherto unknown flow phenomena. This research is divided into two parts; one is to develop the advanced quantitative flow visualization techniques for measuring velocity, temperature, and pressure distributions. The other is to apply these developed measurement techniques to analyze the flow structure and heat transfer characteristics of complex turbulent thermo-fluid flows.

As a 2-D velocity-field measurement technique, our laboratory (FVL) developed the 2-frame PTV technique based on the match probability. It shows much better performance than any conventional velocity field measuring techniques. By synchronizing the CCD camera, a pulsed laser and fan blade phase, the phase-averaged velocity fields of flow around an axial fan and/or a marine propeller were obtained. The original 2-frame PTV (particle tracking velocimetry) technique employs pre-determined matching parameters for entire flow field without considering the local flow structure. By combining adaptively the merits of the 2-frame PTV and conventional PIV method, FVL developed a hybrid PTV technique. It increases the spatial resolution and measurement accuracy and decreases the computation time by determining the matching parameters locally from the preliminary PIV (particle image velocimetry) results. The hybrid PTV method is one of the most updated velocity field measurement techniques in the world. FVL also developed the single-frame PIV system using a high-resolution CCD camera of 2Kx2K pixel and applied to several industrial applications. We also developed the recursive PIV technique with CBC (correlation based correction) method to enhance the spatial resolution of PIV velocity field data. To figure out dominant large-scale structure of turbulent flows precisely, a POD (propper orthogonal decomposition) method was developed. Using the POD method, turbulent flow structures behind a circular cylinder were

divided into several different modes and coherent structures were revealed.

The dynamic PIV system utilizing a high-speed CCD camera and a high-repetition pulse laser was established. The dynamic PIV system was found to be very useful to measure the temporal evolution of velocity field of unsteady turbulent flows.

FVL also developed the micro-PIV method and X -ray PIV technique. Both velocity field measurement techniques can be used to visualize the flow phenomena inside micro-channels and bin-samples. Using the micro-PIV system, the flow characteristics inside micro-channels having different inlet shape were analyzed and the electro-kinetic effects were also analyzed. The X -ray PIV technique using a synchrotron radiation source was well- suited to visualize internal structures or flow patterns inside opaque materials and living organism. FVL visualized the refilling flow in xylem vessels of bamboo leaf and measured human blood flow using the X -ray PIV technique.

As 3-D velocity field measurement techniques, FVL developed 3-D stereoscopic PIV /PTV methods for measuring 3-D turbulent shear flows. The stereoscopic PIV /PTV technique can measure three velocity components in a measurement plane using two CCD cameras. In addition, FVL also developed a digital holographic PTV (HPTV) technique to measure three velocity components inside of a volume of flow. The HPTV method was applied to a turbulent jet flow successfully.
The holographic interferometer, LIF (Laser Induced Fluorescence) and TLC (Thermo chromic Liquid Crystal) thermometry were developed to measure temperature field of thermal-fluid flows. The PSP pressure field measurement technique that can be applied to a subsonic incompressible flow was developed and applied to an impingement jet successfully.
These newly developed advanced flow visualization techniques were applied to several turbulent shear flows and hydrodynamics which have been difficult to analyze with conventional measurement techniques and obtained useful results.
The advanced flow visualization techniques developed can be applied to analyze flow structure and heat transfer characteristics of complex turbulent thermo-fluid flows that have not been hitherto resolved. It will be very useful in resolving problems of public interests such as energy saving and environment protection. Based on the advanced flow visualization techniques, FVL will become one of the most advanced leading research groups and will have strong competitiveness in the field of experimental fluid mechanics.
The advanced flow visualization techniques are the core technology in establishing the domestic industrial fundamental and enhancing the national technology competitiveness. FVL will contribute to improving the efficiency of turbomachinery, energy saving, acoustic noise reduction, and to solving environmental pollution issues. Therefore, this research plays an important role not only in the advancement of thermo-fluid sciences, but also in contributing to the development of domestic industrial technologies in the economic/industrial point of view.

목차 Contents

• 제 1 장 연구개발과제의 개요...28
• 제 2 장 국내외 기술개발 현황...30
• 제 3 장 연구개발수행 내용 및 결과...32
• 가. 2차원 속도장 측정기술 개발 및 성능 검증...32
• 나. 3차원 속도장 측정기술 개발 및 성능 검증...46
• 다. 온도장/압력장 측정기술 개발 및 성능 검증...58
• 라. 난류전단유동에의 응용연구...68
• 마. 수력학분야에의 응용연구...88
• 바. 미세유동에의 응용연구...96
• 제 4 장 목표달성도 및 관련분야에의 기여도...106
• 제 5 장 연구개발결과의 활용계획...116
• 제 6 장 연구개발과정에서 수집한 해외과학기술정보...117
• 제 7 장 참고문헌...120