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정현파 형상의 노즐을 갖는 제트 유동에 대한 실험적 연구
김학림(Hak Lim Kim),S. Rajagopalan,이상준(Sang Joon Lee) 한국가시화정보학회 2008 한국가시화정보학회 학술발표대회 논문집 Vol.- No.2
In this study the flow pattern of a jet with two sinusoidal nozzle exit configurations such as inphase and 180o out-of-phase was investigated using a smoke-wire method and a hot-wire anemometry. Mean velocity and turbulence intensity were measured at several downstream locations (0, λ/4 and λ/2) under U<SUB>j</SUB> (exit velocity) of 3 m/s (Re<SUB>D</SUB> = 5000). For the case of in-phase, the potential core lengths exhibited negligible difference with respect to these transverse locations, similar to those of a plane jet. On the other hand, a maximum difference of 30% in the potential core lengths was appeared for the 180o out-of-phase configuration. Significant differences in the distribution of turbulence intensities were also noticed for the out-of-phase nozzle configuration. Flow visualization images seem to suggest the presence of non-symmetric vortices that can yield the differences between the nozzles configurations.
정현파 형상 노즐 평면제트의 유동구조에 관한 실험적 연구
김학림(Hak Lim Kim),이진평(Jin Pyung Lee),이상준(Sang Joon Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
The flow structure of a turbulent plane jet issuing from a sinusoidal nozzle exit configuration was investigated using a hot-wire anemometry and PIV velocity field measurement. The sinusoidal upper and lower plates were arranged to have in-phase and 180° out-of-phase configurations. Hot-wire anemometry was employed to measure the vertical velocity profiles and PIV measurements were conducted to investigate flow structure in the horizontal planes. Mean velocity and turbulence intensity profiles in vertical planes at three spanwise location (0, λ/4 and λ/2) were measured at several downstream locations(x/h = 0.5~6). The jet velocity at the nozzle exit was U<SUB>j</SUB> = 3 m/s (Re<SUB>D</SUB> = 5000). For the case of in-phase nozzle, the length of potential core exhibit negligible difference at three transverse locations. On the other hand, the 180° out-of-phase nozzle configuration has a maximum difference of 30% in the length of potential core. The spatial distribution of turbulent intensity also show significant difference for the out-of-phase nozzle configuration. Flow visualization results seem to support the presence of non-symmetric vortical structure, yielding the large different vortex structure between the nozzle configurations. For the case of in-phase nozzle configuration, the jet flow propagated from the edge of wave pattern nozzle to the jet center and peculiar flow structure was appeared.
김학림(Hak Lim Kim),S. Rajagopalan,이상준(Sang Joon Lee) 한국가시화정보학회 2010 한국가시화정보학회지 Vol.7 No.2
Two turbulent jet with different sinusoidal nozzle exit configurations of in-phase and 180° out-of-phase were investigated experimentally using a smoke-wire method and a hot-wire anemometry. Mean velocity and turbulence intensity were measured at several downstream locations under Re<SUB>D</SUB> = 5000. For the case of in-phase nozzle configuration, the length of potential core exhibits negligible difference with respect to the transverse locations (0, λ/4 and λ/2), similar to that of a plane jet. On the other hand, a maximum difference of 30% in the potential-core length occurs for the 180° out-of-phase configuration. The spatial distributions of turbulence intensities also show significant difference for the nozzle of 180° out-of-phase, whereas non-symmetric distribution is observed in the near-exit region(x/D = 1) for the inphase sinusoidal nozzle jet. Compared to a slit plane jet, the sinusoidal nozzle jets seem to suppress the velocity deficit as the flow goes downstream. The sinusoidal nozzle jet was found to decrease turbulent intensity dramatically. The flow visualization results show that the flow characteristics of the sinusoidal nozzle jet are quite different from those of the slit plane jet.
PIV Measurements of Ventilation Flow inside the Passenger Compartment of a real passenger Car
이진평(Jin Pyung Lee),김학림(Hak Lim Kim),이상준(Sang Joon Lee) 한국가시화정보학회 2009 한국가시화정보학회 학술발표대회 논문집 Vol.2009 No.11
Most vehicles have a heating, ventilating and air conditioning (HVAC) device to control the thermal condition and make comfortable environment in a passenger compartment. The improvement of comfortability of the passenger compartment is crucial for creating comfortable environment and securing driving safety. For this, better understanding on the variation of flow characteristics of ventilation air inside the passenger compartment with respect to the ventilation condition is strongly required. Most previous studies on the ventilation flow, were carried out using computational fluid dynamics (CFD) method or scaledown water-model experiments. In this study, by using a particle image velocimetry (PIV) velocity measurement technique, the ventilation flow inside the passenger compartment of a real passenger car with HVAC system was measured and analyzed experimentally. With varying ventilation mode, the velocity fields inside the vehicle interior were measured at several vertical planes along the spanwise direction. These experimental data will be used for understanding the detailed flow structures and validating numerical predictions.
SKF 525A가 흰쥐의 대동맥에서 Sodium nitroprusside, Acetylcholine, Pinacidil에 의한 이완반응에 미치는 효과
박조영(Jo Young Park),김학림(Hak Lim Kim),김주원(Ju Won Kim),신창열(Chang Yell Shin),최윤미(Yoon Mee Choi),김진학(Jin Hak Kim),안형수(Hyung Soo Ahn),손의동(Uy Dong Sohn),허인회(In Hoi Huh) 대한약학회 2000 약학회지 Vol.44 No.1
TEA, glibenclamide, L-NAME and SKF 525A-induced contraction were investigated using acetylcholine, sodium nitroprusside (SNP, NO donor) and pinacidil (ATP sensitive K+ channel opener) in rat abdominal and thoracic aorta. The relaxant effects of acetylcholine, SNP and pinacidil were not different in the abdominal aorta and in the thoracic aorta. Acetylcholine-induced relaxation was dependent on endothelial cell, but pinacidil was independent endothelia cell. In the presence of TEA, glibenclamide, L-NAME,mepacrine and SKF 525A, acetylcholine and SNP did not change, but pinacidil-induced relaxation was significantly reduced in presence of glibenclamide, which is ATP sensitive K+ channel blocker. SKF 525A, which is inhibitor of cytochrome P450 dependent epoxygenase, partially inhibited the pinacidil-induced relaxation. These results indicate that the pinacidil-induced relaxation may be mediated by ATP sensitive K+ channel and partially by EETS, which is produced by cytochrome P450 dependent epoxygenase.
거대 화상용 PIV 시스템을 이용한 실차 내부 공기벤트 토출흐름의 속도장 측정 연구
이진평(Jin Pyung Lee),김학림(Hak Lim Kim),이상준(Sang Joon Lee) 한국가시화정보학회 2009 한국가시화정보학회지 Vol.7 No.1
Most vehicles have a heating, ventilating and air conditioning (HVAC) device to control the thermal condition and to make comfortable environment in the passenger compartment. The improvement of ventilation flow inside the passenger compartment is crucial for providing comfortable environment. For this, better understanding on the variation of flow characteristics of ventilation air inside the passenger compartment with respect to various ventilation modes is strongly required. Most previous studies on the ventilation flow in a car cabin were carried out using computational fluid dynamics (CFD) analysis or scale-down water-model experiments. In this study, whole ventilation flow discharged from the air vent of a real passenger car was measured using a special PIV (particle image velocimetry) system for largesize FOV (field of view). Under real recirculation ventilation condition, the spatial distributions of streamwise turbulence intensity and mean velocity were measured in the vertical panel-duct center plane under the panel ventilation mode. These experimental data would be useful for understanding the detailed flow structure of real ventilation flow and validating numerical predictions.