• Title, Summary, Keyword: Flow Velocity Distribution

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Mean Velocity Distribution of Natural Stream using Entropy Concept in Jeju (엔트로피 개념을 이용한 제주도 상시하천의 평균유속분포 추정)

  • Yang, Se-Chang;Yang, Sung-Kee;Kim, Yong-Suk
    • Journal of Environmental Science International
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    • v.28 no.6
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    • pp.535-544
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    • 2019
  • We computed parameters that affect velocity distribution by applying Chiu's two-dimensional velocity distribution equation based on the theory of entropy probability and acoustic doppler current profiler (ADCP) of Jungmun-stream, Akgeun-stream, and Yeonoe-stream among the nine streams in Jeju Province between July 2011 and June 2015. In addition, velocity and flow were calculated using a surface image velocimeter to evaluate the parameters estimated in the velocity observation section of the streams. The mean error rate of flow based on ADCP velocity data was 16.01% with flow calculated using the conventional depth-averaged velocity conversion factor (0.85), 6.02% with flow calculated using the surface velocity and mean velocity regression factor, and 4.58% with flow calculated using Chiu's two-dimensional velocity distribution equation. If surface velocity by a non-contact velocimeter is calculated as mean velocity, the error rate increases for large streams in the inland areas of Korea. Therefore, flow can be calculated precisely by utilizing the velocity distribution equation that accounts for stream flow characteristics and velocity distribution, instead of the conventional depth-averaged conversion factor (0.85).

A Study on Flow Velocity Distribution at Inlet and Exit of Diesel Particulate Filter with L-Shape Inlet Connector Using Automatic Measurement (측정자동화에 의한 입구연결부 형상이 L-형인 디젤매연필터 입.출구에서의 유속 분포에 관한 연구)

  • Lee, Choong-Hoon;Bae, Sang-Hong;Choi, Ung;Lee, Su-Ryong
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.4
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    • pp.93-100
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    • 2007
  • The flow velocity distribution at inlet and exit of Diesel Particulate Filter(DPF) by fabricating L-shape connector with the DPF was measured using a Pitot-tube and 2-D transverse machine. An adaptor designed for making the Pitot tube probe access to the inlet and exit of the DPF was connected with the inlet and exit flange of the DPF, respectively. The Pitot tube which was mounted in the 2-D positioning machine could access to the inlet and exit of the DPF through the rectangular window of the adaptor. The L-shape connector in the DPF inlet has a flow guide which is a perforated steel pipe. The flow velocity distribution at the inlet of the DPF showed a chaotic velocity distribution which is different from that with a diffuser type connector. The velocity distribution at the exit of the DPF showed a crown shape which is similar to that of the diffuser type connector. The velocity distribution at the exit of DPF showed different patterns according to the air flow rate.

A Study on Flow Characteristics of a Ginseng Cleaner Using PIV (PIV에 의한 인삼세척기의 특성연구)

  • 송치성
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • pp.140-145
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    • 2000
  • The objective of experimental study is to apply simultaneous measurement by PIV(Particle Image Velocimetry) to high_speed flow characteristics within ginseng cleaner model. Three different kinds of flow rate(15.20 27ℓ/min) are selected as experimental condition. Optimized cross correlation identification to obtain velocity vectors is implemented by direct calculation of correlation coefficients. The instantaneous velocity distribution time0mean velocity distribution and velocity profile are represented quantitatively for the deeper understanding of the flow characteristics in a ginseng cleaner model.

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Measurement of Flow Velocity Distribution at Inlet and Exit of Diesel Particulate Filter (디젤 엔진 매연여과장치 입.출구에서의 유속 분포 측정)

  • Lee, Choong-Hoon;Choi, Ung;Bae, Sang-Hong;Lee, Su-Ryong
    • Journal of the Korean Society for Railway
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    • v.10 no.3
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    • pp.343-349
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    • 2007
  • The flow velocity distribution at inlet and exit of a DPF was measured using a Pitot tube and 2-D positioning equipment. An adaptor which was designed for accessing the Pitot tube probe into inlet of the DPF was fabricated with inlet flange of the DPF. The Pitot tube which was mounted in the 2-D positioning machine could access to the inlet of the DPF through the rectangular window of the adaptor. Automation of the velocity measurement at the inlet and exit of the DPF was effectively achieved and measuring time was reduced drastically. The flow velocity distribution at the inlet of the DPF showed parabola shape with maximum velocity near to the center of the DPF, as expected. The velocity distribution at the exit of the DPF showed crown shape, that is, the flow velocity distribution near to the center of the DPF is lower than that at surrounded peripheral region of the DPF.

Measurement of Flow Field in a Ginseng Cleaner Model Using PIV (PIV에 의한 인삼세척기 모델 내부의 유동계측)

  • 송치성
    • Journal of the Korean Society of Marine Engineering
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    • v.25 no.1
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    • pp.139-145
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    • 2001
  • The objective of experimental study is to apply simultaneous measurement by PIV(Particle Image Velocimetry) to high_speed flow characteristics within ginseng cleaner model. Three different kinds of flow rate(15. 20, 27l/min) are selected as experimental condition. Optimized cross correlation identification to obtain velocity distribution, time-mean velocity distribution, velocity, profile, kinetic energy and turbulence intensity are represented quantitatively for the deeped understanding of the flow characteristics in a ginseng cleaner model.

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Performance Evaluation of the Velocity Profile Integration for the Multi-Path Ultrasonic Flowmeter in Symmetric & Asymmetric Flow Field (대칭 및 비대칭 유동장에서 다회선 초음파 유량계의 유속분포 적분 방법 평가)

  • Kim, Joo-Young;Kim, Kyung-Jin;Park, Sung-Ha
    • 유체기계공업학회:학술대회논문집
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    • pp.370-377
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    • 2002
  • Generally, the system of calculation for the multi-path ultrasonic flow meters can be divided into two methods by how to get the mean velocity, namely, weighting and direct method. Weighting-method derive the mean velocity through modeling in theoretical velocity profile. Direct-method derive the mean velocity though actual flow distribution. The system of calculation varies with maker's transducer configuration and integration method. Each system has merits and demerits. This paper describes the system of integration that calculates line velocity over cross-section of the circular pipe. Flow rate mr discussed in this paper is a difference between theoretical flow rate and integrated flow rate according to values of Reynolds number in symmetric flow field or theoretical flow rate and integrated flow rate according to rotated model in asymmetric flow field.

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MEASUREMENT OF TURBULENCE CHARACTERISTICS BY USING PARTICLE TRACKING VELOCIMETRY

  • Yoon, Byung-man;Yu, Kwon-kyu;Marian Muste
    • Water Engineering Research
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    • v.3 no.2
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    • pp.135-142
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    • 2002
  • This study investigates the effects of sediment on the flow characteristics such as velocity distribution, friction velocity, turbulent intensities, Reynolds stress, etc. Particle tracking velocimetry (PTY) is used to measure the vertical flow field. Results show that flow over the high bed-load concentration region has larger values of mean velocity and friction velocity and smaller values of turbulence intensities, compared to those for flow over the low bed-load concentration region.

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Robust Ultrasound Multigate Blood Volume Flow Estimation

  • Zhang, Yi;Li, Jinkai;Liu, Xin;Liu, Dong Chyuan
    • Journal of Information Processing Systems
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    • v.15 no.4
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    • pp.820-832
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    • 2019
  • Estimation of accurate blood volume flow in ultrasound Doppler blood flow spectrograms is extremely important for clinical diagnostic purposes. Blood volume flow measurements require the assessment of both the velocity distribution and the cross-sectional area of the vessel. Unfortunately, the existing volume flow estimation algorithms by ultrasound lack the velocity space distribution information in cross-sections of a vessel and have the problems of low accuracy and poor stability. In this paper, a new robust ultrasound volume flow estimation method based on multigate (RMG) is proposed and the multigate technology provides detail information on the local velocity distribution. In this method, an accurate double iterative flow velocity estimation algorithm (DIV) is used to estimate the mean velocity and it has been tested on in vivo data from carotid. The results from experiments indicate a mean standard deviation of less than 6% in flow velocities when estimated for a range of SNR levels. The RMG method is validated in a custom-designed experimental setup, Doppler phantom and imitation blood flow control system. In vitro experimental results show that the mean error of the RMG algorithm is 4.81%. Low errors in blood volume flow estimation make the prospect of using the RMG algorithm for real-time blood volume flow estimation possible.

A Study on the Mean Flow Velocity Distribution of Jeju Gangjung-Stream using ADCP (ADCP를 활용한 제주 강정천의 평균유속 분포 추정)

  • Yang, Se-Chang;Kim, Yong-Seok;Yang, Sung-Kee;Kang, Myung-Soo;Kang, Bo-Seong
    • Journal of Environmental Science International
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    • v.26 no.9
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    • pp.999-1011
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    • 2017
  • In this study, the Chiu-2D velocity-flow rate distribution based on theoretical background of the entropy probability method was applied to actual ADCP measurement data of Gangjung Stream in Jeju from July 2011 to June 2015 to predict the parameter that take part in velocity distribution of the stream. In addition, surface velocity measured by SIV (Surface Image Velocimeter) was applied to the predicted parameter to calculate discharge. Calculated discharge was compared with observed discharge of ADCP observed during the same time to analyze propriety and applicability of depth of water velocity average conversion factor. To check applicability of the predicted stream parameter, surface velocity and discharge were calculated using SIV and compared with velocity and flow based on ADCP. Discharge calculated by applying velocity factor of SIV to the Chiu-2D velocity-flow rate distribution and discharge based on depth of water velocity average conversion factor of 0.85 were $0.7171m^3/sec$ and $0.5758m^3/sec$, respectively. Their error rates compared to average ADCP discharge of $0.6664m^3/sec$ were respectively 7.63% and 13.64%. Discharge based on the Chiu-2D velocity-flow distribution showed lower error rate compared to discharge based on depth of water velocity average conversion factor of 0.85.

A Study on the Axial Velocity and Secondary Flow Distributions of Turbulent Pulsating Flow in a Curved Duct (곡관덕트에서 난류맥동유동의 축방향 속도분포와 2차유동분포에 관한연구)

  • 손현철
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • pp.127-133
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    • 2000
  • In the present study flow characteristics of turbulent pulsating flow in a square-sectional 180。 curved duct are investigated experimentally. in order to measure axial velocity and secondary flow distributions experimental studies for air flow are conducted in a square-sectional $180^{\circ}$ curved duct by using the LDV system with the data acquisition and the processing system of the Rotating Machinery Resolver (RMR) and the PHASE software. The experiment is conducted on seven sections form the inlet(${\phi}=180^{\circ}$) at $30^{\circ}$ intervals of the duct. The results obtained from the experimentation are summarized as follows : In the axial velocity distributions of turbulent pulsating flow when the ratio of velocity amplitude(A1) is less than one there is hardly any velocity change in the section except near the wall and any change in axial velocity distribution along the phase. The secondary flow of turbulent pulsating flow has a positive value at the vend angle of $150^{\circ}$ without regard to the ratio of velocity amplitude. The dimensionless value of secondary flow becomes gradually weak and approaches zero in the region of bend angle $180^{\circ}$ without regard to the ratio of velocity amplitude.

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