• Title/Summary/Keyword: Flow Measurements

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Bio Nature Mimic - Simultaneous Measurements of a Seagull Model's Motion and its Flow Fields (생체자연모사 - 갈매기 운동과 유동 동시측정 해석)

  • Doh, Deog-Hee;Baek, Tae-Sil;Cho, Kyeong-Rae;Pyeon, Yong-Beom;Cho, Yong-Beom
    • 한국가시화정보학회:학술대회논문집
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    • 2006.12a
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    • pp.117-120
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    • 2006
  • Inspiring or mimicking biological bodies is regarded as one of a breakthrough in the conventional engineering. The bird's motion is one of the mimicking objects. Seagulls fly under strong storm at sea. An attempt of investigating into the characteristics of a seagull model's motion and its flow fields has been made in this study. Three cameras, two for motion capture and one for flow field, were used. The motions of the seagull's wing have been reconstructed, and the flow characteristics around the wing have been investigated with 2D-PIV measurements.

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Experimental Study on the Wall Jet Flow Induced by Impinging Circular Jet on Arotating Disk (충돌제트로 인한 회전원판 위의 벽제트유동에 관한 실험적 연구)

  • 강형석;유정열
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.12
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    • pp.3386-3394
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    • 1994
  • An experimental study has been performed on the flow over a rotating disk, where the diameter of the disk is 500 mm and the maximum vertical deviation of the upper surface is $50 \mu{m}$ for the whole range of the angular velocity up to 3400 rpm. The flow visualization experiment for the wall jet flow induced by impinging circular jet is carried out using schlieren system and measurements are made by 3-hole and 5-hole pitot tubes. Schlieren photographs show that as the rotating speed increases the wall jet flow becomes more stable and the size of the largest eddies becomes smaller. Measurements for impinging jet flow on the stationary disk verify the accuracy of the present experiment, and those for free rotating disk flow display the existence of transition region from laminar to turbulent flows. Measurements for impinging jet flow on the rotating disk exhibit the interaction between the wall jet and the viscous pumping effect, which explains the decay in size of turbulent eddies illustrated by the schlieren photographs.

Flow Visualizations and Laser Doppler Velocity Measurements in a Fontan Connection

  • Kim, Young-H.;Yoganathan, Ajit P.
    • Proceedings of the KOSOMBE Conference
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    • v.1994 no.05
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    • pp.111-114
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    • 1994
  • Three component velocity measurements with a refractive index-matching technique was used to investigate the flow characteristics in the atrio-pulmomnary (AP) Fontan connection under the steady flow condition. A strong swirl was observed in the extra-cardiac conduit and the main pulmonary artery (MPA). Maximum velocity magnitude in the MPA was about 0.8 m/s near the posterior wall at 6 liter/min. Swirling motion of the flow as well as geometric abnormalities of the connection are important factors in energy loss across Fontan connections.

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Shower-Head Film Cooling on the Leading Edge of a Turbine Blade: Measurements of Local Blowing Ratio and Flow Visualizations (터빈 블레이드 선단에서의 샤워헤드 막냉강 - 국소분사율 측정 및 유동의 가시화 -)

  • Jeong, Chul Hee;Lee, Sang Woo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.3
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    • pp.419-430
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    • 1999
  • Measurements of local blowing ratio and ammonia-diazo flow visualizations have been conducted for a shower-head film cooling on a first-stage turbine stator. In this study, six rows of normal holes are drilled symmetrically on the semicircular leading edge of a simulated blunt body. The measurements show that for an average blowing ratio based on freestream velocity, M, of 0.5, local average mass flow rate through the first two rows of the holes is less than those through the second and third two rows of the holes, and the fraction of mass flow rate through the first two rows to total mass flow rate has a tendency to increase with the increment of M. The flow visualizations reveal that the injection through the first two row results in inferior film coverage even In the case of M = 0.5, meanwhile the row of holes situated at farther downstream location provides higher film-cooling performances for all tested M. This is because film-cooling effectiveness depends on local mainflow velocity at the hole location as well as the mass flow rate through each row.

Effect of Inlet Geometry on Fan Performance and Inlet Flow Fields in a Semi-opened Axial Fan

  • Liu, Pin;Shiomi, Norimasa;Kinoue, Yoichi;Setoguchi, Toshiaki;Jin, Ying-Zi
    • International Journal of Fluid Machinery and Systems
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    • v.7 no.2
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    • pp.60-67
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    • 2014
  • In order to clarify the effect of inlet bellmouth size of semi-opened type axial fan on its performance and flow fields around rotor, fan test and flow field measurements using hotwire anemometer were carried out for 6 kinds of bellmouth size. As results of fan test, the shaft power curve hardly changed, even if the bellmouth size changed. On the other hand, the pressure-rise near best efficiency point became small with the bellmouth size decreasing. Therefore, the value of maximum efficiency became small as the bellmouth size decreased. As results of flow field measurements at fan inlet, the main flow region with large meridional velocity existed near blade tip when the bellmouth size was large. As bellmouth size became smaller, the meridional velocity at fan inlet became smaller and the one at outside of blade tip became larger. As results of flow field measurements at fan outlet, the main flow region existed near rotor hub side.

Visualization of Vortex Flow around Coolant Outlets Using PIV and LDV (PIV와 LDV를 이용한 냉각수 토출구 주위의 와류 가시화 연구)

  • Hong, Ji-Woo;Shin, Su-Yong;Ahn, Byoung-Kwon
    • Journal of the Korean Society of Visualization
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    • v.19 no.3
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    • pp.136-142
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    • 2021
  • Submerged and semi-submerged vehicles expel cooling water through an outlet. In this process, induced noise and vibration by the flow around the outlet have been reported, and it may cause problems directly related to survivability of the navy vessels. The coolant outlet has a net-type structure and circular columns are mostly used. In this study, flow measurements using PIV and LDV were performed for different type outlets; conventional (flat plate with round bar) and improved (flat and flat plate) configurations. Experiments were conducted at a cavitation tunnel where pressure and steady flow rate conditions are ensured for sufficient time to measure the flow. The average velocity field of the outlets were measured and compared through LDV measurements, and instantaneous vorticities were evaluated through PIV measurements. The results show that the improved type of the outlet is advantageous in terms of flow stability compared to the conventional type of the outlet.

An Experimental Study on Flow Characteristics in Volute of Centrifugal Turbomachinery (원심형 터보기계의 볼류트네의 유동특성에 관한 실험적 연구)

  • Jeon, Kyung-Joon;Joo, Won-Gu
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.801-806
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    • 2001
  • The objective of present study is to find the interaction between volute and impeller of the centrifugal turbomachinery with rectangular cross-sectional volute. Flow measurement were taken in shrouded impeller with 12 backward type blades by using a five-hole pressure probe. The measurements are carried out in 7 flow rate, respectively. Primary function of a centrifugal turbo machinery volute is to serve the flow from the impeller and diffuser to pipe system. For the off-design conditions, Influence of pressure distortion was shown by these measurements. As a result, It has caused the decrease of total efficiency of centrifugal turbomachinery. We have also taken data to design volute by these measurements.

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The Effects of Varying Sampling Flow Rates on the Measurements of Total Nitrate and Sulfate in Dry Acid Deposition

  • Park, Jong-Kil;Kim, Jo-Chun
    • Journal of Korean Society for Atmospheric Environment
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    • v.18 no.E1
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    • pp.1-12
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    • 2002
  • One technique for determining dry acid deposition fluxes involves measurement of time - averaged ambient concentrations of dry acid deposition species using filter packs (FP) coupled with estimates of mean deposition velocities for the exposure period. A critical problem associated with filter pack data comparisons between various field sampling networks is the use of diverse sampling flow rates and duration protocols. Field experiments were conducted to evaluate the effects of varying sampling flow rates, from 1.5 to 10 standard liters per minute, on total nitrate and sulfate measurements of specific dry acid deposition species . Collocated FP samplers were used to determine sampling and analysis data reproducibility and representativeness . Ambient air samples were simultaneously collected using groups of filter packs operated at various flow rates over identical 7 day periods. The species measured were sulfur dioxide, particulate sulfate , nitric acid and particulate nitrate. Statistical results (ANOVA; alpha level 5%) showed that neither the low nor high sampling flow rates caused a significant difference in the measurements of total sulfate and adjusted total nitrate (ATN) . However, it was concluded that for high flow rate sampling measurements, total nitrate (TN) could be affected during extended sampling durations because of potential nitric acid overloading and breakthrough. Although the previous workers (Costello, 1990; Quillian, 1990) used much higher sampling flow rates (~ 17 sLpm) than employed here, it was assumed that for a high loading (> 50$\mu\textrm{g}$ HNO$_3$) of nitric acid on the Nylon filters, a significant fraction (~10%) of nitric acid could pass through the Nylon filters and be collected on the carbonate impregnated filters. It was concluded that even at the highest sampling flow rate employed (10 sLpm) at the Cary Forest site, nitric acid breakthrough was less than 10% of the total HNO$_3$ collected. However, for a heavily polluted urban airshed or with longer sampling times , higher filter loadings could result in substantial nitric acid breakthrough and HNO$_3$concentrations would be underestimated.

Analysis and Comparison of Flow Rate Measurements Using Various Discharge Measuring Instrument and ADCP (다양한 유량 측정기기와 ADCP를 이용한 유량 비교 분석)

  • Ji, Ju-Yeon;Park, Seung-Yong;Lee, Gwang-Woo;Park, Gyeong-Min;Hwang, Soon-Hong;Kim, Dong-Ho;Lee, Young-Joon
    • Journal of Environmental Science International
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    • v.22 no.2
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    • pp.251-257
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    • 2013
  • Discharge data examine the process of hydrologic cycle and used significantly in water resource planning and irrigation and flood control planning. It makes high quality discharge data, they carry out research on standard and method of discharge measurement, and equipment improvement. Now various flow meters are utilized to make discharge data in Korea. However, accuracy of equipment and exprerimental research data from measurement are not enough. ADCP(Acoustic Doppler Current Profiler) have been introduced and utilized for flow measurements since the end of 1980's. ADCP flow method is a formal method for flow measurement can easily applyd to relatively large rivers gradually recognized. This equipment can measure the non-contact three-dimensional velocity and water depth data very quickly and efficiently. Also, spatial and temporal resolution of the data is more accurate than any other flow measurement methods which measure flow rate by velocity - area measurement method. In this paper, the velocity is measured using various flow meter and verified the effectiveness by applying from the ADCP in Geum-river. Various flow meters which are med for discharge measurements are VALEPORT002, FLOW TRACKER, PRICE AA and ADCP. The average of five times flow measurement result by ADCP was $10.412m^3/s$, with a standard deviation of 0.68. The repeat test by ADCP and comparison between ADCP and other flow devices to verify the most import factor, flow measurement accuracy. In the result, repeat test of the ADCP showed similar values, flow values were similar to other velocity device results and the average error is 7.7%.

Several Problems in Reactor Coolant System Flow Rate Measurement

  • Ahn, Seung-Hoon;Auh, Geun-Sun;Suh, nam-Cuk;Park, Jun-Sang;Koo, Bon-Hyun
    • Nuclear Engineering and Technology
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    • v.30 no.6
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    • pp.592-608
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    • 1998
  • Inspection of RCS flow measurements for the domestic pressurized water reactors has been performed by the Korea Institute of Nuclear Safety (KINS) as one of the authorized periodical inspection activities. The inspection results for the Westinghouse-type plants reveal that 1) the RCS flow instrumentation has been calibrated by using the initial design and commissioning test result, without reflecting the cycle specific reference flow measurements, 2) the loop-to-loop now variation in the actual flow measurement which has not been considered in the safety analysis affects the asymmetric How transient results, and 3) the measured RCS flows in Kori 3 and 4, Yonggwang 1 and 2 do not support the definition of the best estimate RCS flow, approaching the RCS flow limit. In this study, the revealed problems were discussed with review of the design and the RCS flow measurement uncertainty evaluation, and the technical approaches and recommendations for resolving these problems were proposed.

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