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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.
EXPERIMENTAL STUDY OF THE FLOW CHARACTERISTICS IN AN AUTOMOTIVE HVAC SYSTEM USING A PIV TECHNIQUE
지호성,이상준 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.5
Air flow inside an automotive HVAC module was visualized using a high-resolution PIV technique with varying temperature control modes. The PIV (particle image velocimetry) system used for the experiment consisted of a 2- head Nd:YAG laser (125 mJ), a high-resolution CCD camera (2 K × 2 K), optics and a synchronizer. A real automotive HVAC module was used as a test model, and some of its casing parts were replaced with transparent windows to capture the flow images of the laser-light-sheet illumination. In addition, instant velocity fields were measured for three different temperature control modes by adjusting the temperature baffle. Characteristics of the air flow inside the automotive HVAC were then evaluated based on the time-averaged PIV data. Results from the experiment showed that flow for the warm mode loses more momentum due to its complicated flow path. Thus, the present PIV data can be used to validate numerical prediction and to improve the performance of HVAC modules. Air flow inside an automotive HVAC module was visualized using a high-resolution PIV technique with varying temperature control modes. The PIV (particle image velocimetry) system used for the experiment consisted of a 2- head Nd:YAG laser (125 mJ), a high-resolution CCD camera (2 K × 2 K), optics and a synchronizer. A real automotive HVAC module was used as a test model, and some of its casing parts were replaced with transparent windows to capture the flow images of the laser-light-sheet illumination. In addition, instant velocity fields were measured for three different temperature control modes by adjusting the temperature baffle. Characteristics of the air flow inside the automotive HVAC were then evaluated based on the time-averaged PIV data. Results from the experiment showed that flow for the warm mode loses more momentum due to its complicated flow path. Thus, the present PIV data can be used to validate numerical prediction and to improve the performance of HVAC modules.
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..