• Journal of the KSME
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• v.25 no.1
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• pp.32-38
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• 1985

지금까지의 계산된 직접 분사식 디이젤기관에서의 분무유동 현상은 실린더내에서의 공기유동과 공기밀도의 온도에 대한 변화를 고려하지 않은 경우이다. 디이젤 연소의 모델링을 위한 몇가지 단계, 즉 (1) 연소실내에서 공기유동을 무시한 경우의 분무유동 특성 (2) 공기유동 (swirl, squish, turbulence)을 고려한 경우에서의 분무유동 특성 (3) 연소실내에서의 분무제트와 주위 기체사이에의 열 및 질량의 이동현상 (4) 연소실 벽면과 연소가스 사이에의 열역학적 관계 의 4가지 단계중 제 1단계에 해당하는 모델로써 보다 완벽한 가정과 정확한 입력 데이터를 이용하면 좋은 예측결과를 나타낼 수 있는 자료가 될 수 있겠으며 공기유동을 고려한 경우의 분무유동 또한 프로그램이 거의 완성단계에 있으므로 가까운 시일내에 이용할 수 있으리라 믿는다.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.5
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• pp.37-50
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• 2007

This study investigated the characteristics of spray generated by a liquid coaxial swirl injector used in a combustor of the liquid rocket engine. The linear stability analysis considered long and short wave was introduced in liquid sheet breakup. Through the hydrodynamic analysis the initial liquid sheet thickness spray angle and injection velocity were predicted. To evaluate the effect of turbulence model standard $k-{\varepsilon}$ and RNC $k-{\varepsilon}$ model were applied to numerical calculation and it was known that RNC $k-{\varepsilon}$ model was more applicable to predict spray characteristics. On the basis of this evaluation validation of the developed model was performed with swirl injector installed in LPRE and the predicted results of breakup length, spray angle, and SMD agreed well with experiments qualitatively and quantitatively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.253-256
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• 2006

A numerical study for spray flow of fuel and oxidizer droplets in the combustion chamber has been conducted prior to the analysis of spray combustion of the liquid rocket engine. As the spray combustion model, DSF model and Euler-Lagrange scheme have been used. While the coupling effects of the droplets between gas phase and evaporated vapor have been calculated using PSIC model, SIMPLER algorithm and QUICK scheme have been used as numerical schemes. As the results, the calculations have shown velocity and temperature distribution in combustion chamber as well as mole fraction of fuel and oxidizer.

• Journal of Bio-Environment Control
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• v.11 no.2
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• pp.93-100
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• 2002

This study was carried out not only to develop CFD model for numerically simulating fog cooling system but also to verify the validity of the developed model by data measured in fag cooling greenhouse. In addition the developed model was applied to investigate the effects of spraying water temperature, spraying water amount, spraying interval and evaporation percentage on the performance of the fog cooling system. According to the simulation results, the temperature differences between the measured and predicted temperatures at each measurement point were $0.1~1.4^{\circ}C$ in case of no shading and $0.2~2.3^{\circ}C$ in close of shading. The humidity differences were 0.3~6.0% and 0.7~10.6%, respectively in the cases of no shading and shading. Because the predicted data showed a good agreement with the measured ones, the developed model is supposed to be able to predict the cooling effect of the fog cooling system. The performance of fog cooling system was greatly influenced by spraying water amount, spraying interval and evaporation percentage, but it was not influenced by spraying water temperature.

• Journal of ILASS-Korea
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• v.4 no.1
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• pp.1-12
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• 1999

• Journal of ILASS-Korea
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• v.4 no.2
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• pp.1-9
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• 1999

• Journal of ILASS-Korea
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• v.5 no.4
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• pp.1-11
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• 2000

• Journal of ILASS-Korea
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• v.4 no.3
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• pp.1-7
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• 1999

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.04a
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• pp.11-11
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• 1999

액체 램제트 연소기는 흡입공기와 분무, 혼합 그리고 이에 따른 연소 등 일련의 과정에 따라 다수의 복잡한 현상들이 상호 밀접하게 관련되어 있다. 본 연구에서는 액체 램제트 연소기내의 유동특성을 파악하기 위해서 2차원 및 3차원 연소기 형상에 대해서 수치적 실험을 수행하였으며, 격자구성은 연소기에 공기를 공급하고 연료를 분무하는 공기 유입관 영역과 연소실 영역, 그리고 출구 대기 영역으로 나누어 독자적으로 격자를 생성시켰다. 2차원과 3차원 유동해석을 비교하였고 분무모델의 적용에 따른 연소특성 및 분사위치에 따른 연소특성을 비교하였다. 유동해석 결과 2차원과 3차원의 유동특성은 달랐으며, 분무모델을 적용해야 정확한 연소 유동 현상을 예측할 수 있음을 알 수 있었다. 그리고 유입관의 안쪽에 연료의 분사위치를 준 경우가 연소의 안정화에 필요한 재순환영역으로의 연료의 혼합이 잘 되어 유입관 바깥쪽에 연료를 분사시키는 것보다 좋은 분사위치임을 알 수 있었다.

• Fire Science and Engineering
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• v.23 no.1
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• pp.48-54
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• 2009

The present study has been performed to investigate the effect of statistical number of droplets on the simulation of the sprinkler spray using fire field model. In order to simulate the sprinkler spray characteristics, the present study uses NIST Fire Dynamics Simulator version 5.2. A group of Lagrangian particles with similar droplet characteristics, such as diameter, velocity, temperature and so on, is represented by parcel concept to decrease the total number of droplets tracked in the simulation. The present study introduces a new parameter to represent the ratio between real number of droplets and computational parcels. The dependency of the number of parcels on the fire suppression characteristics and spray patterns is quantitatively examined for different ratio between the real number of droplets and computational parcels.