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정상적인 엔진 작동 조건에서 열선 공기 유량계의 성능 분석
유성출(Seoung-Chool Yoo) 한국자동차공학회 2020 한국 자동차공학회논문집 Vol.28 No.12
Flows in the bypass tube and main bore of a hot-wire air flow meter were investigated by using high speed flow visualization and two component laser Doppler velocimetry. Although high speed flow visualization shows important information for a qualitative analysis, it does not provide the quantitative information needed to specify the local flow fields. Regions of interest were identified by using high speed flow visualization. The velocities in these regions were then quantified by using two component laser Doppler velocimetry. The hot-wire air flow meter outputs were compared with the velocities measured via laser Doppler velocimetry in the bypass tube at the element location at an engine speed of 2800 rpm. This comparison was used to determine the difference of the sensitivity and response time. For the comparisons, hot-wire air flow meter output voltages were scaled to fit the maximum and minimum of the velocity profiles. Both profiles are smooth and they are well matched, except for the out-of-phase condition. The phase difference between the hot-wire air flow meter voltage output and the laser Doppler velocimetry measurement was about 40 crank angle degrees, with the hot-wire lagging the laser Doppler velocimetry measurement.
Laser Doppler Velocimetry를 이용한 Sodium Lauryl Sulfate의 피부자극 측정
이정기(Jeong Ki Rhee),김형옥(Hyung Ok Kim),김정규(Jeung Kyu Kim),김정원(Chung Won Kim) 대한피부과학회 1989 대한피부과학회지 Vol.27 No.2
It is desirable to use more safe, objective, non-invasive method than visual scoring for the evaluation of irritation reaction and determine the optimum eoncentration of sodium lauryl sulfate(SLS) as a positive irritant control in routine patch test. In this study, SLS was applied to the volar forearm of ll non-atopic, healthy volunteers in concentrations of 0.5, 1.0, 2.0, and 5.0% under occlusion for 24h. The blood flow in test sites exposed to SLS was tecorded by laser Doppler velocimetry (LDV). The test sites were scored visually and the skin blood flow was measured at 24h, 48h, and 72h after the application of FiLS. We obtained the following results,' 1. There was a good correlation between visual scoring and skin blood flow using LDV(p = 0.4547). 2. 5.0% SLS could be used as a positive irritant control in routine patch test (p (0,05).
대형 캐비테이션 터널 내 선박 모형의 3차원 선체 반류 계측을 위한 레이저 유속계 개발
백부근,안종우,설한신,박영하,김기섭,전호근 대한조선학회 2017 大韓造船學會 論文集 Vol.54 No.6
Large Cavitation Tunnel (LCT) of KRISO enables us to conduct cavitation tests of the propeller attached to a ship model. As the ship model tests are done at rather high Reynolds number of 107~108, flow measurement system such as pitot tube cannot be employed because of structural safety problems in its system and difficulties in installing it within the test section. Thus, KRISO has developed new 3-D LDV system used in large test section of LCT. There are several difficulties in using 3-D LDV, which did not allow efficient operation of it. The first trouble was the calibration using the conventional pin hole. To make the focus with same laser-beam waists at the wanted position, the high spatial resolution CCD is utilized in the calibration procedure for 3-D LDV. The off-axis configuration provides two velocity components in the horizontal plane and on-axis configuration gives third velocity component in the vertical plane. The horizontal velocity components are also obtained in the coincidence mode, which prevents any misleading results in the off-axis configuration. The nominal wake of Aframax tanker model is measured by the developed 3-D LDV system. The measured hull wake showed good agreement with that obtained by CFD calculation.
최종운,김용평 慶熙大學校 레이저 工學硏究所 1996 레이저공학 Vol.7 No.-
A noble laser Doppler velocimetry employing a CO?? laser has been developed by using the optogalvanic effects. It is obtained as much as 60 kHz of Doppler frequency shift for the rotating disk, which shows a good linear relationship with velocity of rotating disk. It is also verified the frequency dependence on the angle between the moving direction of rotating disk and incidence laser beam.
Mojtaba Mehrjooei,Nader Montazerin,Abraham Damangir 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.4
Mixing layers are sensitive to the mixing angle and turbulence in the primary streams. Although there is extensive available research on this rather basic flow, there are still no suggestions for a clearly best configuration. For example, the combination of a laminar initial boundary layer and a large mixing angle has received little attention. In this work we test a new experimental configuration with large mixing angle and laminar/turbulent initial boundary layer that was not examined experimentally by LDA and PIV. This setup is expected to be a representation of the initial conditions that must result in better mixing. A plane mixing layer with a velocity ratio of 0.6 is produced by rebuilding an open circuit wind tunnel. Extensive calibration tests on velocity profiles and Reynolds stresses established the position of the self similar region. Velocity field measurements with laser Doppler anemometer (LDA) and particle image velocimeter (PIV) showed enhanced mixing layer growth. PIV plots showed the presence of stream-wise and cross stream vortices in the self-similar region without any considerable change in turbulence characteristics to that of reported in the literature. The article presents a combination of different experimental results that give a deeper understanding of this very configuration.
Velocity measurements in complex flows of non-Newtonian fluids
Muller, Susan J. The Korean Society of Rheology 2002 Korea-Australia rheology journal Vol.14 No.3
Experimental methods for making quantitative measurements of velocity fields in non-Newtonian fluids are reviewed. Techniques based on light scattering spectroscopy - laser Doppler velocimetry and homodyne light scattering spectroscopy, techniques based on imaging the displacement of markers - including particle image velocimetry and molecular tagging velocimetry, and techniques based on nuclear magnetic resonance imaging are discussed. The special advantages and disadvantages of each method are summarized, and their applications to non-Newtonian flows are briefly reviewed. Example data from each technique are also included.
대형 캐비테이션 터널 내 선박 모형 주위 유동 계측을 위한 LDV 시스템
백부근(Bu Geun Paik),안종우(Jong Woo Ahn),박영하(Young Ha Park),김기섭(Ki Sup Kim),김건도(Guen Do Kim) 한국가시화정보학회 2010 한국가시화정보학회 학술발표대회 논문집 Vol.2010 No.11
The MOERI(Maritime & Ocean Engineering Research Institute) has recently established LDV(laser Doppler velocimetry) system to measure the hull wake behind a ship model. One dimensional LDV system with 1600mm expander is successfully employed in the large cavitation tunnel and obtained reliable hull wakes of LNG ship model. Three dimensional LDV system is also set up for the measurement of a complicated 3-D flow around ship appendages such as propeller and rudder. The calibration process is found to be very important and critical in the 3-D LDV measurement. The difficulties in establishing 3-D LDV system are briefly introduced in the present paper.
M. KHALED,M. GAD EL RAB,F. HACHEM,H. ELHAGE,A. ELMARAKBI,F. HARAMBAT,H. PEERHOSSAINI 한국자동차공학회 2016 International journal of automotive technology Vol.17 No.4
Fans are often tested without downstream blockage and, thus, the performance is considerably different when the fan is mounted in a vehicle as part of a cooling system and where high blockage effect is present downstream. The aim of the present work is to analyze by laser Doppler velocimetry LDV measurements the topology of the flow induced by a fan incorporated in a simplified underhood model reproducing engine blockage and to study the blockage effect of the engine positioning on the flow induced by the fan. The distance between the fan and the engine block affects the mean flow axial velocity U. The vertical velocity component W is greatly influenced by the variation of the distance between the fan and the engine block, both in magnitude and topology.
김용평,황대식,이병욱,최종운 慶熙大學校 레이저 工學硏究所 1999 레이저공학 Vol.10 No.-
In this study, we have constructed laser Doppler velocimetry system using self-mixing effect. A theory of self-mixing effect has been theoretically described. Also we have compared the value of Doppler shifted frequency with the variaton of velocity. Frequency dependence on the angle between the moving direction of rotating aluminum wheel and incident beam also has been proved. We can see that the Doppler signal shows a good linear relationship with velocity of rotating disk.