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반경비 및 각속도의 변화에 따른 Taylor 유동에 관한 연구
배강열(K. Y. Bae),김형범(H. B. Kim),정희택(H. T. Chung) 한국전산유체공학회 2007 한국전산유체공학회 학술대회논문집 Vol.2007 No.-
This paper represents the numerical study on Taylor flow according to the radius ratio and the angular velocity for flow between tow cylinder. The numerical model is 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 86.8 mm, 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. The critical Taylor number is calculated by theoretical and numerical analysis, and the results is showed the difference about 土10 %. As Re/Rec is increased, Taylor vortex is changed to wary vortex, and then the wave number for azimuthal direction is increased. Azimuthal wave according to the radius ratio is showed high amplitude and low frequence in case of small radius ratio, and is showed low amplitude and high frequence in case of large radius ratio.
이동식 미분무수 노즐의 소화 특성에 대한 수치 시뮬레이션
배강열(K. Y. Bae),정희택(H. T. Chung),김형범(H. B. Kim),김찬희(C. H. Kim),이창효(C. H. Lee),김창(C. Kim) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
In the present study, the numerical investigation on the effects of water mist spray has been carried out for the fire suppression characteristics. 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 of L×W×H=4.0×4.0×2.5 m and a water mist nozzle that be installed 1.0 m from pool, and the whole walls are assumed the open. In the study, the parameter of simulation has two type that one is consisted of 24 hole on the primary flow surroundings and the other has 8 hole except the primary flow. Finally, the nozzle type that has 24 hole is appeared lower the characteristic of fire suppression than another type because of the flow through many holes is bad impact for the primary flow. The extinguishing time is obtained 65 sec in case of B-type and 170 sec in case of A-type, and B-type showed high effect of fire suppression about 2.6 times than A-type,
탄소발열체의 외부유속 및 직경변화에 대한 비정상상태에서의 수치해석적 연구
배강열(K. Y. Bae),이윤환(Y. H. Lee),이상용(S. Y. Lee),이칠순(C. S. Lee),김봉곤(B. G. Kim),이상철(S. C. Lee) 한국동력기계공학회 2006 한국동력기계공학회 학술대회 논문집 Vol.- No.-
This paper represents the numerical analysis in unsteady state on the variation of diameter and environmental velocity of carbon heating source. In general heating system, the oil and sheath heater is widely used, but these systems have many problems. So, the heating source with carbon ingredient has been researched in many country about manufacture, thermal and electrical properties. In this research; the carbon heating source was studied through numerical analysis on several conditions of unsteady state, heat generation, diameter and environmental velocity. The temperature distributions at steady state are appeared as a non-proportional linear pattern with variations of environmental velocity due to the Nesselt number with convective heat flux is proportioned to 0.805 of Reynolds number. As the radius is increasing, the temperature distributions is appeared the minus tilt because of the environmental condition is cooling by constant temperature. So, the correlation equation between temperature at steady state and environmental velocity was obtained.