• International Journal of Aeronautical and Space Sciences
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• 제7권2호
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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.

• 대한기계학회논문집
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• 제11권5호
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• pp.746-754
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• 1987

본 연구에서는 X형 프로우브에 Mojolla의 방법을 적용하였으며, 경사프로우브 에는 프로우브의 경사각도와 회전각도에 따른 속도성분과 출력전압과의 관계를 유도하 여 적용하였으며, 이들 방법에 의한 3차원 유동계측의 정확성과 적용법위를 조사하였 다.

• 대한기계학회논문집B
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• 제20권11호
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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.

• 공학논문집
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• 제2권1호
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• pp.5-11
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• 1997

입자 물질의 흐름(granular flow)은 일반 산업체의 거의 모든 공정에서 발생한다. 본 논문은 중력 하에서 경사진 슈트 (chute)를 통하여 흐르는 입자들의 속도를 측정하기 위하여 고속 디지털 영상을 이용한 방법을 논한다. 유리 입자 들이 이 실험에서 사용되었다. 유리 입자 들의 평균 속도를 측정하기 위하여 블록 매칭 (block matching)이 사용되었으며 유리입자 들의 평균속도는 변동 정규 상관 함수에 보간법을 적용함으로서 화소 간격보다 적은 단위로 측정하였다.

• 한국안전학회지
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• 제10권2호
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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.

• 대한기계학회논문집B
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• 제38권3호
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• pp.197-202
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• 2014

촉매 변환기의 효율은 촉매 물질이 포함되어 있는 하니콤 브릭 입구의 유동장 분포와 밀접한 관계가 있다. 하니콤 브릭 표면의 유동장 분포가 균일하지 않으면 시스템의 전환 효율이 감소하고 균일한 유동장 분포를 갖는 촉매 변환기에 비해 크기가 커져 제작비용도 증가한다. 따라서 촉매 변환기의 내부유동 해석은 매우 중요하다. 본 연구에서는 변환기 내부 하니콤 브릭 사이부분과 2번째 하니콤 브릭 출구부분의 유동분포를 단축을 따라 37.8 l/s와 94.4 l/s 유동영역에서 측정하였다. 또한, 자동차 제작사에서 이루어진 전산해석 결과를 측정 결과와 비교하여 실험적으로 검증하였다. 하니콤 브릭 사이부분의 ${\upsilon}$-속도분포 측정은 다소 변화하는 유동패턴이 형성되는 것을 보여주지만 입구 반대쪽 벽 부근영역에서 음의 유동장이 형성되고 음의 속도는 감소하여 중심 부근에서는 정체현상을 보이고 계속 입구 쪽까지 지속되는 것을 보여준다. 대부분의 속도 값에서 전산해석 결과는 측정치에 비하여 크게 나타났다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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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.

• 대한기계학회논문집B
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• 제22권12호
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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.

• 대한기계학회논문집B
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• 제20권4호
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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.

• 대한기계학회논문집B
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• 제27권1호
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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.