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김중연(Joongyeon Kim),박선희(Sun Hee Park),전병희(Byung-Hee Chun),김성현(Sung Hyun Kim),정병훈(Byung Hun Jeong),한정식(Jeong Sik Han) 한국추진공학회 2010 한국추진공학회지 Vol.14 No.2
As hypersonic flight speeds and engines efficiencies increase, heat loads on an aircraft and it’s engine increase. Because the temperature of the air flow is too high to cool the aircraft structure at hypersonic flight speeds, it is essential to use the aircraft fuel as the primary coolant. Endothermic fuels are liquid hydrocarbon aircraft fuels which are able to absorb the heat loads by undergoing endothermic reactions, such as thermal and catalytic cracking. The endothermic reactions are improved by catalysts which change the extent of reaction and product distribution. At high temperature, liquid hydrocarbons would lead to coke formation that can reduce the effectiveness of heat exchanger and cause rapid degradation of the catalyst, thus endothermic capacity of endothermic fuels is limited to the temperature at which coke doesn’t form. In this study, the essential cooling technologies by applying endothermic fuels and the properties of the endothermic fuels are described.
CMC 모델을 이용한 난류 비예혼합 Syngas 화염장 해석
김군홍(Gunhong Kim),이정원(Jungwon Lee),김용모(Yongmo Kim),안국영(Kook-Young Ahn) 한국연소학회 2006 KOSCOSYMPOSIUM논문집 Vol.- No.-
The fully coupled conditional moment closure(CMC) model has been developed to realistically simulate the structure of complex turbulent nonpremixed syngas flame, in which the flame structure could be considerablyl influenced by the turbulence, transport history, and heat transfer as well. In order to correctly account for the transport effect, the CMC transport equations fully coupled with the flow and mixing fields are numerically solved. The present CMC approach has successfully demonstrated the capability to realistically predict the detailed structure and the overall combustion characteristics. The numerical results obtained in this study clearly reveal the importance of the convective and radiative heat transfer in the precise structure and NOx emission of the present confined combustor with a cooling wall.
백국현,임유진 한국추진공학회 2005 한국추진공학회지 Vol.9 No.3
The effect of coolants has been studied on the burning properties of low burning rate HTPB/AP composite propellant containing Oxamide or Melamine as coolant for the gas generator. With increasing the content of coolant, the burning rate and the flame temperature could be lowered and the effect on flame temperature was about the same for two coolants. However due to the different thermal decomposition properties of coolant, the burning rate of Melamine propellant was found to abnormally decrease if 200 μm AP was partially replaced with 6 μm AP. 가스발생기용 저 연소속도 HTPB/AP계 고체추진제의 조성에서 냉각제인 Oxamide와 Melamine이 추진제의 연소특성에 미치는 효과를 고찰하였다. 냉각제의 함량을 증가시키면 연소속도와 화염온도가 낮아지고, 두 냉각제의 화염온도에 미치는 영향은 유사하였다. 그러나 냉각제의 열분해 특성 차이로 인하여 Melamine 추진제에서는 비정상적으로 200 μm AP의 일부를 6 μm AP로 대체하면 연소속도가 오히려 감소하는 현상을 나타내었다.
김우순,김경우,김동현 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.1
Nickel-based heat resisting alloys are commonly used for high temperature applications such as in aircraft engines and gas turbines. In this paper, the machinability of Nickel-based heat resisting alloy was investigated with respect to the wear and the chip formation by tool type and cutting condition. Relationship between three types of tool and chip formation Bras experimentally investigated. Among the three types of tool tested, coated tools(CVD, PVD) are available for the difficult-to-cut-materials such as Nickel-based heat resisting alloy and etc.