• Title/Summary/Keyword: 입자 영상 속도계

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Experimental Study of Flow Fields around Cylinder Arrays Using PIV (PIV를 이용한 두 원주 주위의 유동장에 관한 실험적 연구)

  • Jeon, Wan-Soo
    • Journal of Ocean Engineering and Technology
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    • v.10 no.3
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    • pp.83-88
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    • 1996
  • 두 인접한 원주 유동장을 입자 영상 속도계를 이용하여 연구하였다. 실험은 회류수조에서 행하였다. 흐름방향에 평행하게 배치하는 방법과 직교배열의 두가지 방법으로 원주를 배열하였다. 연구 결과는 다른 연구자의 결과와 일치함을 보여주었다. 본 연구를 통하여 입자 영상 속도계를 이용한 유동장 해석이 대단히 효과적임을 알 수 있었다.

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Study of Drag Force of Subsea Pipeline in Trench (트랜치내의 해저 관로 항력 변화 고찰)

  • 조철희;김경수;홍성근
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.13-17
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    • 2000
  • 해저관로가 노출되어 있을 경우 파도와 조류 등에 의한 외적 하중으로부터 안정적이어야 한다. 트랜치 구간 내의 해저관로에 작용하는 유체 입자의 속도와 가속도는 해저면과 비교하여 볼 때 현저히 감소하므로 감쇄 계수를 사용하여 트랜치 구간 내에 설치되는 해저관로의 안정성을 해석한다. 그러나, 다양한 트랜치 구간의 깊이와 기울기에 대한 감쇄 계수에 대해 많은 자료가 부족하여 실제 설계에는 한정된 계수들이 이용된다. 본 논문에서는 다양한 깊이와 기울기를 가진 트랜치 구간의 실험 모형을 제작하여 회류 수조에서 P.I.V(입자 영상 속도계) 기법을 이용하여 여러 속도에 대하여 실험을 수행하였다. 다양한 트랜치 구간 내의 실린더 주변의 유동 특성과 유체 입자의 수평 속도를 측정하여 항력 감쇄 계수를 산출해 냈으며 실제 해양 공사에서 적용 가능한 안정성 해석 기준을 제시하였다.

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Flow Field Analysis around Multi-Cylinders Using Particle Image Velocimetry (PIV를 이용한 다수원주 주위 유동장 해석)

  • 전완수;박준수;권순홍;하동대;최장운;이만형
    • Journal of Ocean Engineering and Technology
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    • v.10 no.3
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    • pp.89-95
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    • 1996
  • The flow field around four cylinders for various angles was investigated utilizing particle image velocimetry(PIV) technique. Flow field was recorded by video camera first. Then application of PIV technique was done to the flow field. The results turned out to be useful to analyze complex flow field around multiple cylinders.

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A Study on Biased Flow Region Using PIV Technique (PIV기법을 이용한 편향흐름 발생영역 규명)

  • Na, Jeong-Heon;Kwon, Sun-Hong
    • Journal of Ocean Engineering and Technology
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    • v.13 no.1
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    • pp.105-112
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    • 1999
  • This research is an experimental investigation of the region of the Biased Flow. This experiment was carried out in a circulating water channel, and the results are analyzed by using the PIV technique. The results are presented in velocity vector field, velocity contour and vorticity contour. The results were compared with those of Zdravkovich which were carried out in a wind tunnel. These results will be very useful to verify numerical codes.

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A Study on Characteristics of Condensation for RAC Using Flow Visualization Technique (유동 가시화 기법을 이용한 RAC의 이슬 맺힘 특성에 관한 연구)

  • Lee, A-Mi;Kim, Dong-Won;Na, Seon-Uk;Ko, Han-Seo
    • Proceedings of the KSME Conference
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    • pp.3092-3097
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    • 2007
  • Although noise of a RAC can be reduced effectively by decreasing RPM, condensation problems can occur to reduce reliability of the RAC for low RPM. Thus, this research has been performed to propose a design guideline of the RAC for low-noise RPM with high reliability. The internal and external flows of the RAC have been visualized and analyzed by a PIV technique to solve the condensation problem at an outlet and impeller. Then, the design guideline has been proposed by the analyzed results and confirmed by wind-tunnel and noise tests to reduce the condensation problem. Finally the shapes of the outlet with reduced condensation problem and the impeller with low noise have been obtained in this study.

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Effect of Ambient Pressure on Internal Structure of a DI Gasoline Spray (직분식 가솔린 분무의 내부구조에 미치는 분위기 압력의 영향)

  • 성기진;최동석;김덕줄
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.6
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    • pp.19-26
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    • 2002
  • The objective of this study is to examine a DI(Direct Injection) gasoline spray development process under different ambient pressures using PIV(Particle Image Velocimetry). fuel spray experiments were performed within a constant volume chamber. The spray structure, velocity maps, velocity and vorticity contours were obtained to investigate its spray characteristics. It was found that higher ambient pressure has a significant effect on radial growth of the spray. The position which has a maximum velocity moved from the spray edge to the spray center as ambient pressure was increased. Higher ambient pressure moved a maximum vorticity position upward of the spray.

A Study on the Flow Characteristics of Gasoline Spray using Digital Image Processing (디지털 이미지 법을 이용한 가솔린 분무의 유동 특성에 관한 연구)

  • 이창식;이기형;전문수;김영호
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.4
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    • pp.219-227
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    • 1998
  • This paper describes the fuel spray characteristics of gasoline port injectors such as the breakup procedures of liquid fuel, breakup and extinction behaviors of fuel spray at nozzle tip, time history of SMD and velocity distribution of fuel spray in the direction of fuel stream. Pintle-type gasoline fuel injector was used to analyze mentioned spray characteristics. In order to visualize the fuel spray behaviors and to measure the droplet mean diameter and velocities of spray droplets, the Schlieren method, digital image processing and auto-correlation PIV were applied in this study. In addition, the spray characteristics according to the variation of time were considered. The results of fuel spray show that the liquid sheet breakup starts at 10mm downstream actively. The flying time is approximately 4msec between 50mm and 80mm down the nozzle tip. Also, SMD of fuel spray, the number of droplets and fuel velocity distribution at each point of downstream are discussed.

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Investigations of Three Dimensional Flow Characteristics in the Liquid Ramjet Combustor using PIV Method (PIV를 이용한 액체램제트 연소기내의 3차원 유동특성 연구)

  • Yang, G.S.;Sohn, C.R.;Cho, D.W.;Kim, G.N.;Moon, S.Y.;Lee, C.W.
    • Proceedings of the KSME Conference
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    • pp.271-275
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    • 2001
  • Three dimensional flow characteristics in a liquid fuel ramjet combustor are investigated using PIV method. The combustors have two rectangular inlets that form 90 degree each other. Three guide vane is installed in each rectangular inlet to improve the flow stability. We made three cases of test combustors in which those inlet angles are 30 degree, 45 degree and 60 degree. Each combustor easily changes the size of combustor's recirculation zone with the replacement of combustors dome. The experiments are performed in the water tunnel test with the same Reynolds number in the case of Mach 0.3 at inlet. PIV software is developed to measure the flow field in the combustor and the accuracy of developed PIV program is verified with rotating disk experiment and standard data. The experimental results show that the two main streams from rectangular inlet collide near the plane of symmetry and generate two large longitudinal vortex, A large and complex three-dimensional recirculating flow is measured in the recirculation zone.

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A study on the inner flow fields characteristics of the Semi-active muffler (반능동형 머플러 내부의 유동장특성에 관한 연구)

  • Park Kyoung-Suk;Heo Hyung-Seok;Park Se-Jong;Son Sung-Man;Kim Dong-Hyun
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.3
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    • pp.125-131
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    • 2006
  • Recently air pollution has become an important issue. So, as tile number of vehicles increases, the noise pollution has become one of the most serious social issues nowadays. It is a muffler, which is one of the vehicle components. that has the hugest impact on the noise from the vehicle. And it also has a direct influence on the engine performance. So lately the research is proceeding on tile semi-active muffler which can control the back pressure variably by setting up the exhaust variable valve in the baffle to improve its internal structure. The inner parts of muffler which consist of a baffle, pipes and etc. appear to have the complicated turbulence phenomena by the pulsational wave of an unsteady state in the engine and by the structural characteristics of the inner parts. To analyze these phenomena, it is required to have an analysis of its constant quantity and quality. Therefore this study is to analyze with PIV measurement which can analyze the time and space variables, not with the point measurement method like former multi-point anemometer. It is to suggest proper design variables which need to make internal structure of the muffler improve though comparison between the passive type muffler and the semi-active muffler by fabricating a muffler which can be visualized.

A Study on the Spray Characteristics of Swirl Injector for Use a HCCI Engine using Entropy Analysis and PIV Technique (엔트로피 해석과 PIV를 이용한 HCCI 엔진용 스월 인젝터의 분무 특성 해석에 관한 연구)

  • 안용흠;이창희;이기형;이창식
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.1
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    • pp.39-47
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    • 2004
  • The objective of this study is to analyse the spray characteristics according to the injection duration under ambient pressure condition and to investigate the relationship between vorticity and entropy for controlling diffusion process that is the most important thing during the intake stroke injection process. Therefore, the spray velocity was obtained by using the PIV method that has been an useful optical diagnostics technology, and vorticity calculated from spray velocity component with vorticity algorithm. In addition, the homogeneous diffusion rate of spray was quantified by using the entropy analysis based on the Boltzmann's statistical thermodynamics. From these method, we found that as injection duration increases, spray velocity increases and the location of vortex is moved to the downstream of spray. In the same condition, as the entropy decrease, mean vorticity increases. This means that the concentration of spray droplets caused by the increase of injection duration is more effective than the increase of momentum dissipation.