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李鳳來 홍익대학교 산업기술연구소 1994 産業技術 Vol.3 No.-
The purpose of this study is to evaluate different processes of the jet flow development with different boundary conditions. In this study, some experiments have been conducted on conventional axisymmetric jet flow of uniform velocity at the outlet to obtain basic data needed. The jet leaving the open end of a considerably long square nozzle and the conventional axisymmetric jet with uniform velocity distribution at the outlet were compared to evaluate their processes of development by measuring the average velocity. turbulance and intermittency factor. It is found the field of flow is classified into three regions, namely, the potential core region, the characteristic decay region and the axisymmetric decay region. The results of the measurements indicated that the momentum is conserved and that the jet flow is similar to a two-dimensional flow in the potential core region and the characteristic decay region. The behavior of the jet flow in the free jet region is almost the same as an axisymmetric jet expanding into infinite surrounding stationary air. In this investigation, several cross-sections were chosen downstream from the outlet to obtain the half-value radius by measuring each velocity distribution. It was found that the half-value radius started to increase linearly from a point of about 10D dowmstream from the outlet. The method treated here can be applied to a jets with any type of the flow condition.
미소기포의 성장 및 붕괴로부터 음장에 의한 발광에너지에 관한 기초연구
李鳳來 홍익대학교 산업기술연구소 1994 産業技術 Vol.4 No.-
Sonoluminescence(SL) is the phenomenon of light emission associated with the collapse of a single bubble, levitated in a standing wave field. In this study the intensity of sonoluminescence depending on the liquid density has been investigated by using the analytical solution of the Euler equation for the gas inside bubble. It has been found that the increase in the density of liquid reduces the compression ability of the gas inside bubble so that the intensity of sonoluminescence decreases. It has also found that the driving frequency of ultrasound affects the intensity of the sonoluminescence significantly.
李鳳來 홍익대학교 산업기술연구소 1995 産業技術 Vol.5 No.-
Sonoluminescence(SL) is the phenomenon of light emission associate with the collapse of a single bubble levitated in standing wave field. In this study the intensity of sonoluminescence depending of the liquid density has been investigated by using the analytical solution of the Euler equation for the gas inside bubble. It has been found that the increase in the density of liquid reduces the compression ability of the gas inside bubble so that the intensity of sonoluminescence decreases. It has also found that the driving frequency of ultrasound affects the intensity of the sonoluminescence significantly.
李鳳來,崔成旭 홍익대학교 산업기술연구소 1998 産業技術 Vol.8 No.-
We install various model in test section of wind tunnel. With constant velocity, we give each variable distance and then take data from pressure holl by using Micro-Manometer and observe pressure difference of body's surface and see real-body flowtype by using smogwrite method with scanning point based on flow type's size. We connect pitot tube with travers. We see pressure difference of surrounding body moving travers up-down and see flow property accoding to pressure difference by using data here
李鳳來 홍익대학교 산업기술연구소 2002 産業技術 Vol.12 No.-
Conventional aerodynamic simulations have carried out over a hundred grid point or wind tunnel experiment by using Supercomputer. It takes a long time to get a result. This paper has dealt on flow characteristics of automobile in the flow field. Fluent has been able to apply to the industrial field in these days. This new method has practically on early designing phase of automobile. This paper has been focused on the necessity of rear-spoiler, the peculiarity of aerodynamic drag, and the level of drive safety. A complex wake structure in the immediate rear of the car has been confirmed. The distributions of the surface pressure coefficient are not sensitively dependent on the Reynolds Number.
李鳳來 홍익대학교 산업기술연구소 2006 産業技術 Vol.16 No.-
Conventional aerodynamic simulations have carried out over hundreds of grid point or wind tunnel experiment by using Supercomputer. However, it takes so long time to get a exact result. This paper has dealt on flow characteristics of automobile in the flow field. Fluent program has been able to apply to the industrial field these days. This new analysis method has been practically on early designing phase of automobile. This paper has been focused on getting an result of the flow resistance adjusted to the front surface of 3 kind of vehicle - sedan, truck, bus. Each has been specially designed to compare one with the others. This result of the measure will be helpful in case of getting an most efficient mileage analysis for each vehicle, measuring safety of vehicles, and designing more originative outward appearance. We really hope that our experiment is invaluable for the future of vehicles.
李珍熙,李鳳來 홍익대학교 산업기술연구소 1993 産業技術 Vol.2 No.-
It has been tried to solve the heat transfer problem of composite materials. Homogenization technique was used to compute the thermal conductivity matrices of base cells which constituted the composites with repeated patterns. The homoge nization technique made it possible to compute the heat transfer of composite materials with lower degrees of freedom compared to those of other numerical methods. It also was shown that the eigenvalues of homogenized thermal conductivity matrices were the same for identical materials irrespective of their microscale orientations.