• International Journal of Vascular Biomedical Engineering
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• v.2 no.1
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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.

• 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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.672-674
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• 2017

The addition of swirl is a common technique used in premixed combustors in order to gain stability of the combustion with the improvements in mixing characteristics. recent experimental studies have observed that the addition of swirl oxidizer flow can effectively reduce the combustion instability in hybrid rocket. Investigation was continued to analyze the effect of the swirl on the internal flow of hybrid rocket engine main combustion chamber. The flow influenced by wall blowing as a representation of fuel evaporation interacts with swirling flow. Swirl angle increases, the amplitude of the combustion pressure decrease as the unstable combustion processes. These results suggest that the oxidizer swirling flow by the swirl angle causes the change of the turbulent flow characteristics inside the combustion chamber and suppresses the factors causing the combustion instability.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.1
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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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• v.62 no.2
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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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• 2002.06a
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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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.67-70
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• 2008

Production and dissipation of turbulent structure in a swirl stabilized combustor was investigated using three-dimensional Large Eddy Simulation analysis. The combustor of concern is the LM6000, lean premixed dry low-NOx annular combustor, developed by GEAE. Inlet condition was based on experimental data. Strong vortex breakdown in main stream, vortex ring proceeding downstream, and the turbulent structure periodically oscillating have been observed. Reasonable agreement was obtained by comparison of the results with experiments and previous LES studies.

• Journal of computational fluids engineering
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• v.5 no.1
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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.

• Journal of the Korean Society of Combustion
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• v.7 no.2
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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.