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노즐내 물체의 후류가 아음속 이차원 제트구조에 미치는 영향에 관한 수치해석적 연구
오대근,윤복현,김태호 국립7개대학공동논문집간행위원회 2004 공업기술연구 Vol.4 No.-
A turbulent wake generated by a cylinder in nozzle contraction affects to the jet flow characteristics. In this study, a computational work to investigate the effect of the turbulent wake on two-dimensional subsonic jet was carried out with three different kinds of nozzle. computations are applied to the two-dimensional unsteady, Navier-Stokes equations. Several kinds of turbulent models and wall functions are employed to validate the computational predictions. It was known that the wake flow enhanced the spread of the jet flow, compared with no wake flow condition. It was also found that the jet core is shortened by the wake flow developed from a control cylinder.
지면효과익을 지나는 가/감속 유동의 공력특성에 관한 수치해석적 연구
오대근,윤복현,김태호 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-
Recently, several kinds of experimental and computational studies are being carried out to investigate the WIG(Wing In Ground Effect) aerodynamic characteristics which are of practical importance to develop the new ground transportation vehicle system. These works are mainly based upon conventional wind tunnel tests, but many problems associated with the WIG aerodynamic characteristics cannot be satisfactorily resolved due to the wind tunnel blockage effects or string problems to support the test object. To overcome the problems, it is necessary to develop a novel simulator appropriate to the WIG aerodynamics. The lift increased in accelerating and decelerating flows without the Reynolds number, and the increase degree appeared remarkably as an dimensionless acceleration coefficient increased.
실린더 후류를 이용한 아음속 디퓨저 유동의 제어에 관한 연구
오대근,윤복현,김태호 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-
The present study addressed a computational work to investigate the influence of a turbulent wake flow on the pressure recovery of subsonic diffuser. The turbulent wake is generated by a cylinder with a small diameter, which is installed at the diffuser inlet of a 2-dimensional diffuser Computation are applied to three-dimensional steady Navier-Stokes equations. The computational results are qualitatively well compared to existing experimental results. The results show that the diffuser pressure recovery of the subsonic diffuser is dependent on the diameter and location of the cylinder. It is found that a certain diameter and location of cylinder to generate the turbulent wake give a better pressure recovery, compared with no cylinder flow
노즐내 이차원 물체에 의한 피동제어된 아음속 제트구조에 관한 연구
오대근,윤복현,김태호 국립7개대학공동논문집간행위원회 2003 공업기술연구 Vol.3 No.-
A turbulent wake generated by a cylinder in nozzle contraction affects to the jet flow characteristics. In this study, a computational work to investigate the effect of the turbulent wake on two-dimensional subsonic jet was carried out with three different kinds of nozzle. Computations are applied to the two-dimensional unsteady, Navier-Stokes equations. Several kinds of turbulent models and wall functions are employed to validate the computational predictions. It was known that the wake flow enhanced the spread of the jet flow, compared with no wake flow condition. It was also found that the jet core is shortened by the wake flow developed from a control cylinder.
실린더 후류를 이용한 2차원 디퓨저 성능개선에 관한 수치해석적 연구
오대근,윤복현,김태호 국립7개대학공동논문집간행위원회 2004 공업기술연구 Vol.4 No.-
The present study addresses a computational work to investigate the influence of a turbulent wake flow on the pressure recovery of a two-dimensional subsonic diffuser. The turbulent wake is generated by a cylinder with a small diameter, which is installed at the diffuser inlet. Computation is applied to two-dimensional steady Navier-Stokes equations. The computational results are qualitatively well compared to existing experimental data. The results show that the diffuser pressure recovery is strongly dependent on the diameter and location of the cylinder. It is found that there is a certain diameter and location of cylinder for the diffuser pressure recovery to be most enhanced. Compared with no cylinder case, the diffuser performance increases up 24.
이상덕,김종환,정남진,오대근,오성종 한국국제농업개발학회 2003 韓國國際農業開發學會誌 Vol.15 No.2
This work is dedicated to main directions of Agricultural science policy of Russia during the transition to the market economy. In this study, Russian R&D system, R&D expenditure and structure of research institutes were introduced. Especially, Studies on organizations such as RFBR : Russian Foundation for Basic Research, RFTD : Russian Fund for Technological Development, Russian Foundation for Promotion of Small Enterprises in S&T, FPP : Fund for presidential Programs, SRC : State Research Center, ISTC : International Science & Technology Center were carried out. Analysis of the problems of Agricultural Science sector of Russia shows the situation is very complicated. Despite all efforts of Government, the national institutes is still in crisis. It is clear today that without energetic and intelligent reforms, it would be impossible to implement resonable reorganization of Agricultural sector and have to strong and deserved science and technical sector in Russia.