http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
직사각형 프리즘 주위의 유동구조에 대한 경계층 두께의 영향
지호성,김경천,이승홍,부정숙,Ji, Ho-Seong,Kim, Kyung-Chun,Lee, Seung-Hong,Boo, Jeong-Sook 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.6
Effect of boundary layer thickness on the flow characteristics around a rectangular prism has been investigated by using a PIV(Particle Image Velocimetry) technique. Three different boundary layers(thick, medium and thin)were generated in the Atmospheric Boundary Layer Wind Tunnel at Pusan National University. The thick boundary layer having 670 mm thickness was generated by using spires and roughness elements. The medium thickness of boundary layer($\delta$=270 mm) was the natural turbulent boundary layer at the test section floor with fairly long developing length(18 m). The thin boundary layer($\delta$=36.5 mm) was generated on the smooth panel elevated 70cm from the wind tunnel floor. The Reynolds number based on the free stream velocity(3 ㎧) and the height of the model(40 mm) was 7.9$\times$10$^3$. The mean velocity vector fields and turbulent kinetic energy distributions were measured and compared. The effect of boundary layer thickness was clearly observed not only in the length of separation bubble but also in the location of reattachment point. The thinner the boundary layer thickness, the higher the turbulent kinetic energy Peak around the model roofbecame. It is strongly recommended that the height ratio between the model and the approaching boundary layer thickness should be encountered as a major parameter.
자동차 HVAC용 Blower Unit 내부 유동장의 PIV 계측
지호성,김보람,이상준,Ji, Ho-Seong,Kim, Bo-Ram,Lee, Sang-Joon 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.5
Flow characteristics inside a blower unit of an automotive HVAC module were investigated experimentally using a high-resolution PIV technique. The PIV system consists of a 2-head Nd:YAG laser, a high-resolution CCD camera, optics and a synchronizer. The prototype siroco-fan with forward-curved blades was operated under the same condition of real car. The scroll casing was made transparently for capturing clear flow images. The time-averaged velocity fields were measured in three cross sections. Flow is accelerated with going toward the outer wall of scroll due to centrifugal force and large pressure gradient formed in the region between the fan and the outer casing wall. The presence of the cut-off region and diffusing duct of fan outlet influences largely the flow structure inside the blower unit.
온도조절 격판 변화에 따른 차량용 HVAC 내부 유동의 PIV속도장 측정 연구
지호성(Ho Seong Ji),이상준(Sang Joon Lee) 한국가시화정보학회 2008 한국가시화정보학회지 Vol.6 No.1
Air flow inside an automotive HVAC module has been investigated using a high-resolution PIV technique with varying the temperature operation mode. The PIV system consists of a 2-head Nd:YAG laser (125 mJ), a high-resolution CCD camera (2K×2K), optics and a synchronizer. A real automotive HVAC module was used directly under real operating condition. Some casing parts of the HVAC module were replaced with transparent windows for capturing clear flow images with laser light sheet beam illumination. Time-averaged velocity fields were obtained for two different temperature control modes. Flow characteristics of the air-conditioned air flow inside the automotive HVAC system for the two temperature baffle conditions were evaluated.
지호성(Ho Seong Ji),이정엽(Jung Yeop Lee),이상준(Sang Joon Lee) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
In order to investigate flow characteristics of blood flow in a micro tube (100㎛ in diameter) with respect to hematocrit, in-vitro experiments were carried out using a micro-PIV technique. The micro-PIV system consists of a microscope, a 2 head Nd:YAG laser, a 12 bit cooled CCD camera and a delay generator. Blood was supplied into the micro tube using a syringe pump. Hematocrit for blood was controlled by 20%, 30% and 40%. The blood flow has a cell free layer near the tube wall and its thickness is changed with increasing the flow rate and hematocrit. The hemorheological characteristics such as shear rate and viscosity were evaluated using the velocity field data. As the flow rate increased, the blunt velocity profile in the tube center was sharpened. The viscosity of blood was also steeply increased by decreasing shear rate, especially in the region of low shear rate, changing RBC rheological properties. The variation of velocity profile and blood viscosity shows typical characteristics of Non-Newtonian fluids. Based on the inflection points, the cell free layer and two-phase flow consisted with plasma and suspensions including RBCs were clearly discriminated.
PIV를 이용한 HVAC용 Blower 주의 유동특성에 대한 실험적 연구
지호성(Ho Seong Ji),김보람(Bo Ram Kim),김석(Seok Kim),이상준(Sang Joon Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Flow characteristics around a blower unit have been investigated using a high-resolution PIV technique. The PIV system consists of a 2-head Nd:YAG laser, a high-resolution CCD camera, optics and a synchronizer. The prototype centrifugal fan with forward-curved blades of an automotive HVAC module was used directly. Only the scroll casing was made transparently for capturing flow images. The time-averaged velocity distributions show that velocities are accelerated with going toward the outer wall of scroll due to large pressure gradient between the fan and outer casing wall. The presence of cut-off angle region and diffusing duct of fan outlet influence the flow structure largely.
지호성(Ho Seong Ji),이상준(Sang Joon Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Flow characteristics of blood in a micro-channel with stenosis were investigated using a high-speed micro PIV system. The width and depth of the PDMS microchannel were 100㎛ and 50㎛, respectively. The width of the micro-scale stenosis is 15㎛. Heparinized human blood was supplied into the micro-channel using a syringe pump. The visualization flow images show clearly the deformation of RBCs at the stenosis region. Cell free layer and two-phase behavior of blood flow were also visualized. The velocity profiles measured using the high-speed micro PIV system are well agreed with the theoretical prediction of flow in the micro stenosis.
쾌적성 향상을 위한 차량용 공조장치 내부 유동에 대한 가시화 연구
지호성(Ho Seong Ji),정요한(Yo Han Jeong),백제현(Jae Hyun Baek),이상준(Sang Joon Lee) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Air flow inside an automotive HVAC module was visualized using a high-resolution PIV technique with varying the temperature operation mode. The PIY system consists of a 2-head Nd:YAG laser(125mJ), a high-resolution CCD camera(2K×2K), optics and a synchronizer. A real automotive HVAC module was used directly as a test model. Some casing parts of the HVAC module casing were replaced with transparent windows for capturing flow images with laser light sheet beam illumination. Time-averaged velocity fields were measured for different temperature control modes. Flow characteristics of the air flow inside the automotive HVAC system were evaluated from the PIY data and numerical data..