• 제목/요약/키워드: Flow Measurements

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Control of Delta-Wing Vortex by Micro-Fin-Type Leading-Edge Flap

  • Sohn, Myong-Hwan;Chung, Hyoung-Seog;Cho, Dong-Hyun
    • International Journal of Aeronautical and Space Sciences
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    • v.7 no.2
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    • pp.128-136
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    • 2006
  • The present study examined the effects of micro leading-edge flaps on the vortex characteristic changes of a double-delta wing through pressure measurements of the wing upper surface and PIV measurements of the wing-leeward flow region. The experimental data were collected and analyzed while changing the deflection angle of the leading-edge flaps to investigate the feasibility of using micro leading-edge flaps as flow control devices. The test results revealed that the leading edge modification could greatly alter the vortex flow pattern and the wing surface pressure of the delta wing, which suggested that the leading-edge flaps could be used as an effective device for the control of delta-wing vortex flow.

A method for measuring the three-dimensional flows by the hot-wire anemometers (열선 유속계를 이용한 3차원 유동의 계측 방법)

  • 강신형;유정열;백세진;이승배
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.5
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    • pp.746-754
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    • 1987
  • A method for measuring three-dimensional turbulent flows by the hot-wire anemometer is introduced. Mojolla's method using the X-type probe is adopted and modified for the slantwire probe without the linearizer. The probe is aligned with specified angles to the given uniform flow and the shear layer to verify the measuring errors due to the three-dimensionality and the turbulence level. Errors in the measurements of mean velocities and Reynolds stresses increase with the degree of three dimensionality in the flow. The incoming flow angle of 20 degree seems to be the limit of reasonable flow measurements. But there still appear large data scatterings in Reynolds shear stresses.

A method for the determination of transient flow rates from pressure measurements (압력측정을 이용한 과도기유량의 결정방법에 관한 연구)

  • Lee, Seong-Rae
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.11
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    • pp.3649-3654
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    • 1996
  • A transient hydraulic flow rate computation scheme is described here so that the transient hydraulic flow rate can be determined using the dynamic pressure measurements at the ends of a straight flow line with a dynamic model of the hydraulic line. This method can be applied to determine the orifice ares of high response valve. Simulation results indicate that the method is relatively robust to realistic levels of uncertainties in the fluid properties.

Velocity Measurement of Granular Flow with Block Matching (블록 매칭을 이용한 Granular Flow의 속도 측정)

  • Lee, Jin-Geol
    • The Journal of Engineering Research
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    • v.2 no.1
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    • pp.5-11
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    • 1997
  • The flow of granular materials is common to many industrial processes. This paper discusses a methodology which utilizes high speed digital imaging to measure velocity of dry granular solids flowing down an inclined chute under the action of gravity. Glass particles have been used as granular solids in our experiment. The proposed technique utilizes block matching for spatially averaged velocity measurements of the glass particles. The velocity measurements are refined to the subpixel resolution by the variance normalized correlation with interpolation.

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Study About a New Propulsion System Using CRP(II) (Noise and Flow of the Counter-Rotating Propeller) (CRP를 사용한 추진기관에 관한 연구(II) (CRP의 소음과 유동에 관하여))

  • 정진덕;이동호
    • Journal of the Korean Society of Safety
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    • v.10 no.2
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    • pp.39-45
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    • 1995
  • Three-dimensional flow measurements were conducted between the rotors of the CRP To understand mean flow phenomena of the CRP's, the results of the three-dimensional measurements were shown. Interaction noise of the CRP, which increases the overall ,level of sound pressure In the new propulsion system, is documented by using the double conditional sampling technique. The rear rotor will increase the axial flow between the rotors of a CRP depending upon the relative locations between the forward and the rear rotor blades. The decay and spreading of the forward wakes and the upstream propagation of the rear blade disturbances are shown along with the interaction of the flow disturbances by the two rotors of blades.

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Flow Field Measurement in Catalytic Converter-Comparison with Computational Fluid Dynamics Analyses (촉매 변환기의 내부 유동장 측정-CFD 해석과 비교)

  • Yoo, Seoung-Chool;Jang, Sung-Kuk
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.3
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    • pp.197-202
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    • 2014
  • The efficiency of a catalytic converter depends on the flow distribution across a system's chemically active substrate. If irregularities or non-uniform flow patterns exist, the system's conversion efficiency decreases, whereas the manufacturing cost increases. Therefore, it is important to analyze the internal flow of a catalytic converter. In this study, flow pattern measurements along the minor axis were recorded at the mid and exit planes of a ceramic honeycomb catalytic converter at flow rates of 37.8 l/s and 94.4 l/s. Flow distributions of the measurement plans were compared with an automotive company's computed velocity profiles. Measurements along the minor axis showed uneven velocity profiles. The ${\upsilon}$-velocity components between the honeycomb bricks were small but somewhat erratic opposite the intake side of the converter, however, they became flatter in measurements recorded near the intake entrance. For almost all velocity values, the computer model suggested velocities greater than the measured values.

Air Flow in a Neonate Incubator: Flow Visualizations, Hot-Wire Velocity Measurements and Computational Fluid Dynamics (신생아 보육기의 공기유동에 관한 유동가시화, hot-wire 속도계측 및 전산유동 해석)

  • Kim, Young-Ho;Kwon, Chi-Ho;Yoo, Seoung-Chool
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.162-168
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    • 2001
  • In the present study, flow visualizations, hot-wire velocity measurements and computational fluid dynamics were performed in order to determine complicated air flow characteristics in a neonate incubator. In this study, following conclusions can be made: (1) The flow visualization technique developed in the present study revealed an enough qualitative information for the flow field in the neonate incubator. Flow structures in a neonate incubator with a realistic three-dimensional shape was successfully visualized the present study. (2) Results from the flow visualization were relatively in good agreements with those obtained from the computational fluid dynamics. (3) Velocities very near the neonate measured by the hot-wire anemometer were relevant to those obtained from the computational fluid dynamics. (4) Temperatures were higher at the neck region and the medial aspect of both thighs, but lower in both extremities. (5) Small vortices between the neonate and the mattress might interfere with convective and evaporative heat transfers on the neonate's surface. In the fluid dynamic aspect, it is important to eliminate the formation of these small vortices for the design of incubator chamber.

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Three-Dimensional Flow Characteristics of a Circular Impinging Jet Normally Oriented to Crossflow (주유동에 수직으로 분사되는 원형 충돌제트의 3차원 유동특성)

  • Lee, Sang Woo;Jeong, Chul Hee
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.12
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    • pp.1735-1745
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    • 1998
  • Oil-film surface flow visualizations and three-dimensional flow measurements using a straight five-hole probe have been conducted for a circular impinging jet which is normally oriented to the crossflow in a channel. Throughout the experiments, the ratio of channel height to injection hole diameter, H/D, is fixed to be 1.0, and blowing ratio is varied to be 1.0, 2.0, 3.0 and 4.0. From the surface flow visualizations for both top wall(target plate) and bottom wall, impinging jet region on the target plate can be clearly identified, and for the small value of H/D = 1.0, presence of the bottom wall changes the near-hole flow structure, significantly. The three-dimensional flow measurements show that in the dawnstream region of the injection hole, there exist a pair of counter-rotating vortices, called "scarf vortices", and the strength of the vortices strongly depends on the blowing ratio. In addition, a new flow model in the flow symmetry plane has been proposed for H/D = 1.0.

Three-dimensional flow and pressure loss of a film-cooling jets injected in spanwise direction (폭방향으로 분사되는 막냉각 제트의 3차원 유동특성 및 압력손실)

  • Lee, Sang-U;Kim,Yong-Beom
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.4
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    • pp.1363-1375
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    • 1996
  • Oil-film flow visualizations and three-dimensional flow measurements using a five-hole probe have been conducted to investigate three-dimensional flow characteristics and total pressure losses of a row of film-cooling jets injected in spanwise direction. For several span-to-diameter ratios, experiments are performed in the case of three velocity ratios of 0.5, 1.0 and 1.5. The flow measurements show that downstream flow due to the injection is characterized by a single streamwise vortex instead of a pair of counter-rotating vortices, which appear in the case of streamwise injection, and the vortex strength strongly depends on the velocity ratio. Regardless of the velocity*y ratio, presence of the spanwise film-cooling jets always produces total pressure loss, which is pronounced when the velocity ratio is large. It has also been found that the production of the total pressure loss is closely related to the secondary vortical flow. In addition, effects of the span-to-diameter ratio on the flow and total pressure loss are discussed in detail.

Jet Impingement Heat Transfer on a Cylindrical Pedestal Encountered in Chip Cooling (충돌제트를 이용한 Pedestal 형상의 칩 냉각연구)

  • Lee, Dae-Hee;Lee, Joon-Sik;Chung, Young-Suk;Chung, Seung-Hoon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.1
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    • pp.1-8
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    • 2003
  • The heat transfer and flow measurements on a cylindrical pedestal mounted on a flat surface with a turbulent impinging jet were made. The experiments were made for the jet Reynolds number of Re = 23,000, the dimensionless nozzle-to-surface distance of L/d = 2~10, the dimensionless pedestal height of H/D = 0~1.5. Measurements of the surface temperature and the Nusselt number distributions on the plate surface were made using liquid crystal and shroud-transient technique. Flow measurements involve smoke flow visualization and the wall pressure coefficient. The results show that the wall pressure coefficient sharply decreases along the upper surface of the pedestal. However, the pressure increases when the fluid escapes from the pedestal and then collides on the plate surface. The secondary maxima in the Nusselt numbers occur in the region of 1.0 $\leq$ r/d $\leq$ 1.9. Their values for the case of H/D = 0.5 are maximum 80% higher than those for other cases. The formation of the secondary maxima may be attributed to the reattachment of flow on the plate surface which was separated at the edge of the pedestal.