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윤용현(Y.H Yoon),김성초(S.C. Kim),조환기(H.K Cho),이상현(S.H. Lee) 한국전산유체공학회 2009 한국전산유체공학회 학술대회논문집 Vol.2009 No.4
New design configurations were developed based on the closed ventilation type igloo nozzle in contrast to the conventional open distribution type. To validate the enhanced performance, the prediction of the exhaust flow patterns of the igloo diffuser was carried out by both experimental and computational simulations. CFD provided detailed parametric studies that significantly reduced the amount of experimentation necessary to alter the design of existing the F-15K igloo exhaust diffuser.
윤용현(Y. H. Yoon),정형석(H. S. Chung),이상현(S. H. Lee) 한국전산유체공학회 2007 한국전산유체공학회 학술대회논문집 Vol.2007 No.-
The prediction of the safe separation of the external stores carried on military aircraft is an important task in the aerodynamic design area having the objective to define the operational, release envelopes. The major concern of this study is only safe jettison problem with ejections This work consists of concept and some results for external store configurations. A Computational Fluid Dynamics technique is applied to calculate the aerodynamic forces. The FLUENT with an implicit Euler solver is used for the present simulations. The computational results are validated against the experimental data.
윤용현(Y.H. Yoon),권기범(K.B. Kwon),홍승규(S.K. Hong) 한국전산유체공학회 2005 한국전산유체공학회지 Vol.10 No.4
A dynamic simulation on the missile staging system is conducted with numerical techniques. Both Euler equations and Navier-Stokes equations are numerically solved respectively. The dynamic simulation of two moving bodies is fully integrated into the computational fluid dynamics solution procedure. The Chimera grid scheme is applied in this simulation for unsteady supersonic flow analysis with dynamic modeling. The objective of the study is to investigate the problem pertaining to possible unstability in missile staging. In addition, the computational comparison between inviscid and viscid flow solvers is also performed in this study.
윤용현(Y.H. Yoon) 한국전산유체공학회 2007 한국전산유체공학회 학술대회논문집 Vol.2007 No.-
A fast and robust method of grid generation to multiple functions has been developed for flow analysis in three dimensional space. It is based on the Non-Uniform Rational B-Spline of an approximation method The grid generation method, details of numerical implementation. examples of application, and potential extensions of the current method are illustrated in this paper.
공기부상 전동 운행체의 지면효과를 받는 3차원 날개에 대한 공력해석 연구
오현준(H. J. Oh),서정희(J. H. Seo),문영준(Y. J. Moon),조진수(J. S. Cho),윤용현(Y. H. Yoon) 한국전산유체공학회 2004 한국전산유체공학회 학술대회논문집 Vol.2004 No.-
Aerodynamic characteristics of three-dimensional wings in ground effect for Aero-levitation Electric Vehicle(AEV) are numerically investigated for various ground clearances and wing spans at the Reynolds number of 2×10^6 Numerical results show that a sizeable three-dimensional flow separation occurs with formation of an arch vortex at the junction of main and vertical wings, and that this is conjectured a primary cause for the high lift-to-drag(L/D) reduction rate of the main wing, when the wing span is decreased. Improvements on L/D ratios of the wings with small spans are pursued by breaking the coherence of superimposed adverse pressure gradients at the wing junction.
정형석(H. S. Jueng),윤용현(Y. H. Yoon),이상현(S. H. Lee) 한국전산유체공학회 2007 한국전산유체공학회 학술대회논문집 Vol.2007 No.-
A critical problem in the integration of stores into new and existing aircraft is the safe separation of the stores from the aircraft at a variety of flight conditions representative of the aircraft flight regime. Typically, the certification of a particular store/aircraft/flight condition combination is accomplished by a flight test. Flight tests are very expensive and do expose the pilot and aircraft to a certain amount of risk. Wind tunnel testing, although less expensive than flight testing, is still expensive. Computational Fluid Dynamics(CFD) has held out the promise of alleviating expensive and risk by simulating weapons separation computationally. The forces and moments on a store at carriage and at various points in the flow field of te aircraft can be computed using CFD applied to the full aircraft and store geometry. This study needs full dynamic characteristics study and flow analysis for securing store separation safety. Present study performs dynamic simulation of store separation with flow analysis using Chimera grid scheme which is usually used for moving simulations.
권기범(Y.H. Yoon),윤용현(S.K. Hong),홍승규(K.B. Kwon) 한국전산유체공학회 2003 한국전산유체공학회 학술대회논문집 Vol.2003 No.-
In this study the numerical analyses on cavity flow in supersonic flow field are conducted. According to the length-to-depth ratio of cavity, the shear layer is changed, consequently influencing on vortex structure inside the cavity. Especially in case the fluid flow outside cavity impinges inside the cavity, the oscillation of the cavity flow is identified. Another result is that though the cavity flow shows the unsteadiness, characteristics of cavity flow can be represented by pressure coefficients converged.
권기범(K. B. Kwon),윤용현(Y. H. Yoon),홍승규(S. K. Hong) 한국전산유체공학회 2004 한국전산유체공학회 학술대회논문집 Vol.2004 No.-
In this study the numerical analysis on staging flow with forward ejector is conducted. The forward ejector plays a vital role in staging, which jets out from aftbody. This staging environment needs careful flow analysis for securing staging safety. Present study investigates the steady inviscid staging flow phenomena with variation of separation distance. The performance index is forebody base pressure coefficients. The three dominant flow phenomena are observed according to separation distance which could be told as impinging stage, cavity vortex dominancy stage, and pure base flow characteristics stage. Impinging stage shows high thrust for forebody as one might think. However, important point is that cavity vortex dominancy stage can be more favorable for separation than impinging stage as one simply think in certain separation distance.