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거주구역내의 분사노즐특성 변화에 따른 화염억제효과에 관한 수치해석적 연구
배강열(Kang-Youl Bae),정희택(Hee-Taeg Chung),김형범(Hyoung-Bum Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.11
In the present study, we carried the numerical investigation on fire suppression according to the performance of spray nozzle in the passenger cabin. The FDS are used to simulate the interaction of fire plume and water mists, and program describes the fire-driven flows using LES turbulence model, the mixture fraction combustion model, the finite volume method of radiation transport for a non-scattering gray gas, and conjugate heat transfer between wall and gas flow. The numerical model is consisted of a rectangular enclosure of L×W×H=4×4×2.5m and a water mist nozzle that be installed 2.2m from fire pool. Finally, because the large droplet size has the high kinematic energy and the long travel distance, the effect of fire suppression is very small than the small size to a fire plume that is installed under spray nozzle. Among the spray nozzle used III present simulation, K-3 by KIMM is showed the high effect of fire suppression because it has the large heat transfer area by suppling the flow rate more than about 6 times than others.
내부회전실린더를 가진 동심환형관에서 반경비의 영향에 관한 수치해석적 연구
배강열(Kang-Youl Bae),김형범(Hyoung-Bum Kim),이상혁(Sang-Hyuk Lee) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
This paper represents the numerical analysis on effects of radius ratio in a concentric annulus with a rotating inner cylinder. The numerical model consisted of two cylinder which inner cylinder is rotating and outer cylinder is fix, and the axial direction is used the cyclic condition because of the length for axial direction is assumed infinite. The diameter of inner cylinder is assumed 86.8mm, the numerical parameters are angular velocity and radius ratio. Also, the whole walls of numerical model have no-slip and the working fluid is used water at 20℃. The numerical analysis is assumed the transient state to observe the flow variations by time and the 3-D cylindrical coordinate system. The calculation grid adopted a non-constant grid for dense arrangement near the wall side of cylinder, the standard k-ω high Reynolds number model to consider the effect of turbulence flow and wall, the fully implicit method for time term and the quick scheme for momentum equation. The numerical method is compared with the experimental results by Wereley and Lueptow, and the results are very good agreement. As the results, TVF isn't appeared when Re is small because of the initial flow instability is disappear by effect of the centrifugal force and viscosity. The vortex size is from 0.8 to 1.1 for TVF at various η, and the traveling distance for wavy vortex have the critical traveling distance for each case.
노즐 특성 변화에 따른 미분무수와 화염과의 상호작용에 관한 수치해석
배강열(Kang-Youl Bae),정희택(Hee-Taeg Chung),김형범(Hyoung-Bum Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
In the present study, the numerical investigation on the effects of water-mist characteristics has been carried out for the fire suppression mechanism. The FDS are used to simulate the interaction of fire plume and water mists, and program describes the fire-driven flows using LES turbulence model, the mixture fraction combustion model, the finite volume method of radiation transport for a non-scattering gray gas, and conjugate heat transfer between wall and gas flow. The numerical model is consisted of a rectangular enclosure of L×W×H=1.5×1.5×2.0m and a water mist nozzle that be installed 1.8m from fire pool. In the study, the parameters of nozzle for simulation are the droplet size and the spray velocity. Finally, the droplet size influences to fire flume on fire suppression than spray velocity because of the effect of terminal velocity, and the optimal condition for fire suppression is that the droplet size and the spray velocity are 100㎛ and 20㎧, respectively.
실린더 내부 유동에서 반경비 및 각속도의 변화에 따른 임계수에 관한 수치해석
배강열(Kang-Youl Bae),김형범(Hyoung-Bum Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
This paper represents the numerical analysis on critical Taylor number according to the variation of radius ratio and angular velocity on flow in cylinder. The numerical model consisted of two cylinder which inner cylinder is rotating and outer cylinder is fix, and the axial direction is used the cyclic condition because of the length for axial direction is assumed infinite. The diameter of inner cylinder is assumed 86.8mm, the numerical parameters are angular velocity and radius ratio. The numerical method is compared with the experimental results by Wereley, and the results are very good agreement. As the results, the vortex size is from 0.8 to 1.1 for TVF at various , and the traveling distance for wavy vortex have the critical traveling distance for each case. Also, the critical Taylor number is calculated by theoretical and numerical analysis, and the results is showed the difference about ±2~3%.
배강열(KANG YOUL BAE),강일권(IL-KWEON KANG),정한식(HAN-SHIK CHUNG) 한국해양공학회 2000 韓國海洋工學會誌 Vol.14 No.2
Recently, due to the environmental pollution and the requirement for the substitute energy, the interest for development of the solar energy system has been highly escalated, It has been approved that the solar energy is a very useful one because of purity and low cost. Some studies about the evaluation of solar radiation on the land has been carried out, but few studies on the sea. This paper deals with a study on the evaluation of solar radiation for development of hot water storage tank by using solar on the sea. The experiments were carried out on the training vessel on the adjacent water of Korea, Japan and China for twenty days. The distributions of solar radiation from the sea were changed into nonlinear in from according to the temperature. The solar radiation on the sea has a great influence on the velocity of wind as well as the temperature. The distribution of solar radiation has higher values on the track of the coastal sea than the open sea at same conditions.
이광성(Kwang-Sung Lee),배강열(Kang-Youl Bae),정효민(Hyo-Min Jeong),정한식(Han-Shik Chung),이광영(Kwang-Young Lee),전지수(Ji-Su Chun) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
This research aims for replacing a general sheath heater and manufactured two kinds of a carbon bar type heating rod. The carbon heating rod have a ingredients of bentonite. graphite. methyl cellulose and water. we compared a performance of temperature between the carbon heating rod and sheath heater. As a main parameters. we changed the input electric power with 50. 100 and 50Watts. The experimental results are as followings; when the input electric power was constant, the carbon heating rod had a minimum electric current, but the input electric voltage was high. Among the two kinds of carbon heating rod. the carbon rod with 27wt[%] of graphite showed a high temperature of 30% than a sheath heater, and the reached time for maximum temperature was very short by comparing to sheath heater. These means that the carbon heating rod will be a good heater for a small size warm air circulator.