• International Journal of Vascular Biomedical Engineering
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• 제2권1호
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• pp.11-16
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• 2004

Both flow visualizations and computational fluid dynamics were performed to determine hemodynamics in a total cavopulmonary connection (TCPC) model for surgically correcting congenital heart defects. From magnetic resonance images, an anatomically correct glass model was fabricated to visualize steady flow. The total flow rates were 4, 6 and 8L/min and flow rates from SVC and IVC were 40:60. The flow split ratio between LPA and RPA was varied by 70:30, 60:40 and 50:50. A pressure-based finite-volume software was used to solve steady flow dynamics in TCPC models. Results showed that superior vena cava(SVC) and inferior vena cava(IVC) flow merged directly to the intra-atrial conduit, creating two large vortices. Significant swirl motions were observed in the intra-atrial conduit and pulmonary arteries. Flow collision or swirling flow resulted in energy loss in TCPC models. In addition, a large intra-atrial channel or a sharp bend in TCPC geometries could influence on energy losses. Energy conservation was efficient when flow rates in pulmonary branches were balanced. In order to increase energy efficiency in Fontan operations, it is necessary to remove a flow collision in the intra-atrial channel and a sharp bend in the pulmonary bifurcation.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1994년도 춘계학술대회
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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.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.672-674
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• 2017

하이브리드 로켓의 연소 실험 과정에서 저 주파수 대역이 증폭하는 연소 불안정이 관찰되었다. 반면, 터빈 연소기에서는 혼합 특성 향상을 통하여 연소의 안정성을 얻기 위해 스월 유동을 사용한다. 본 연구에서는 하이브리드 로켓의 연소 불안정을 감소시키기 위하여 스월 인젝터를 사용하여 실험하였다. 그 결과, 하이브리드 로켓에서 스월 인젝터를 통하여 산화제를 주입한 경우 연소 불안정이 감소하였다. 산화제의 스월 유동의 변화는 연소실 내부의 난류유동 특성을 변화시키며 그 결과, 연소 불안정에 영향을 미친다. 따라서 스월 각도 변화를 통하여 스월 넘버 변화를 변화시킴으로써 유동 특성 변화에 대해 알아보았다. 유동 특성 변화가 주파수 특성에 미치는 영향, 압력진동과 연소진동의 상관관계에 대해 확인하였다.

• 한국안전학회지
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• 제19권3호
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• pp.45-50
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• 2004

4-panel of 1m height and 45cm width were fixed on the $40cm{\times}40cm$ bottom plate and the opening of the panel comer was 5cm. Diameter of stainless vessel is loom and its height is 2cm and it located at the center of the bottom plate. 78mL liquid fuel was filled in the vessel and its depth was 1cm. Flame temperature was measured with K type thermocouple, and radiation heat of flame was measured with heat flux meter. Flame height and its behavior was visualized with video camera. and mass burning rate was measured by fuel combustion time. According to the development of fire, flame swirling was begin. From the experiment the mass burning rate was larger and the height of flame was higher than the usual pool fire flame. Flame temperature and heat flux also increased far more than the pool fire. Consequently the swirling air flow through the openings between the panel and thermal buoyance contribute to increase of heat release rate, flame length and mass burning rate.

• 설비공학논문집
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• 제1권1호
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• pp.21-31
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• 1989

본 연구에서는 경사진 hot-wire probe 의 특성값을 구하고 열선풍속계의 응답식으로부터 수평원통관내에서 3차원 흐름의 속도성분과 난류 강도 그리고 전단 응력을 pitot tube의 결과와 비교 연구하였다. 또한, 속도 및 난류 강도에 관한 유도된 식을 swirling flow에도 적용하여 만족한 결과를 얻었다.

• Korean Chemical Engineering Research
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• 제62권2호
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• pp.191-199
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• 2024

A study was conducted on a tubular heat exchanger to improve its heat transfer rate by using a novel baffle plate design with discontinuous swirling patterns. The design consisted of perforated baffle plates with rectangular air deflectors positioned at varying angles. The tubes in the heat exchanger were arranged in a consistent alignment with the airflow direction and exposed to a uniform heat flux on their surfaces. Each baffle plate included sixteen deflectors inclined at the same angle and arranged in a clockwise pattern. This arrangement induced a swirling motion of the air inside a circular duct where the heated tubes were located, leading to increased turbulence and improved heat transfer on the tube surfaces. The spacing between the baffle plates was adjusted at different pitch ratios, and the Reynolds number was controlled within a range of 16,000 to 29,000. The effects of pitch ratios and inclination angles on the heat exchanger's performance were analyzed. The results indicated that using a baffle plate with rectangular deflectors inclined at 30° and a pitch ratio of 1.2 resulted in an average increase of 1.29 in the thermal enhancement factor.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제24회 KOSCO SYMPOSIUM 논문집
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• pp.113-122
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• 2002

The purpose of this study is to verify that the modified Lagrangian model can predict temperature, flow and scalar fields in the high temperature recirculation region of swirling confined diffusion flame. In the meantime numerical results from EBU and Equilibrium PDF models as well as experimental results are compared with those from the modified Lagrangian model. Adaption of three different turbulent models were accompanied with this procedure. Look-up table of the ignition characteristic time scale which is one of important factors of the Lagrangian model was referred to the 11-step reduced mechanism. Eventually, results with the Lagrangian model show a good accordance with experimental results, which shows the validity of this model. Results from Chen's model differ from those of the others. Numerical results of ${\widetilde{k}$ show significant deviation from experimental results for three models.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.67-70
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• 2008

스월 연소기의 비반응 난류 유동특성을 파악하기 위하여 3차원 Large Eddy Simulation(LES)을 수행하였다. 연소기는 GEAE LM6000 연소기를 이용하였으며, 실제 실험 결과에 따른 인젝터 유입 형상을 적용하였다. 주 흐름 부분에서 강한 vortex breakdown, 중심 재순환영역, 모서리 재순환영역, 축방향으로 전진하는 스월링 형상, 주기적으로 나타나는 난류 구조를 관찰하였다. 계산된 결과는 실제 실험결과와 선행연구자들의 LES 계산결과와 비교하여 잘 맞음을 확인하였다.

• 한국전산유체공학회지
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• 제5권1호
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• pp.8-13
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• 2000

In this study, the spray models incorporated into the GTT code were tested for sprays injected in quiescent swirling gases and for the sprays impinging on a flat wall, and the validity of the models has been confirmed by comparing the calculated results with the experimental data. Using this code, the gas flow, spray behavior and fuel vapor distributions in the combustion chamber of a D.I engine have been numerically analyzed with respect to the constant injection pressure and the injection pressure varying with injection time.

• 한국연소학회지
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• 제7권2호
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• pp.34-41
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• 2002

To investigate the combustion characteristics of a swirling diffusion gas burner with oxygen enrichment, mean temperature, CO, $CO_2$, and HC concentrations were measured at various oxygen enrichment conditions. According to the results, the flame temperature increased and the region of high temperature was expanded with increasing oxygen concentration. The $CO_2$ concentrations increased, while the CO concentrations decreased in proportion to the increase of oxygen concentration. On the other hand, the HC concentrations were decreased and this tendency was very strong at the downstream of the combustor.