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RISS 인기검색어
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- 저자 : 김재수(J. S. Kim) (검색결과 69 건)
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조성일,변기훈,변성훈,김재수,Cho, Seong-il,Byun, Gihoon,Byun, Sung-Hoon,Kim, J.S. 한국음향학회 2018 한국음향학회지 Vol.37 No.4
This paper presents an algorithm for passive localization of a ship by applying the ray back-propagation technique to the ship radiation noise data. The previous method [S. H. Abadi, D. Rouseff and D. R. Dowling, J. Acoust. Soc. Am. 131, 2599-2610 (2012)] estimates the position of a sound source in the near-field environment with no array tilt by using the RBD (Ray-based Blind Deconvolution) and ray back-propagation techniques. However, when there exists an array tilt, the above method leads to a large position estimation error. In order to overcome the problem, this study proposes an algorithm that estimates the position of a sound source by correcting the array tilt using the RBD and ray back-propagation techniques. The proposed algorithm was verified by using the ship noise of SAVEX15 (Shallow-water Acoustic Variability EXperiment in 2015) experimental data.
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역류제트를 이용한 센터바디 디퓨져의 열차폐 특성에 관한 연구
김종록(J.R. Kim),이경환(K.H. Lee),김재수(J.S. Kim) 한국전산유체공학회 2017 한국전산유체공학회지 Vol.22 No.2
In the development of liquid-propellant rocket engines, it is important to simulate high-altitude environments and verify the performance of the engines in these environments. Supersonic diffusers are the most important technology in high-altitude simulation facilities. Using the thermal protection system based on the counter-flow jet, as proposed in this study, the cooling efficiency of the CBD(center-body diffusers) can realize an efficient high-altitude simulation facility for the liquid-propellant rocket engine. The analysis for the supersonic flow with a counter-flow jet was performed by experimental and numerical methods. The thermal protection effect by the counter-flow jet in the center body diffuser was analyzed by a numerical method. When the pressure ratio of counter-flow jet injection is less than 0.5, the cooling effect is insignificant, but when the pressure ratio is 1.0 or more, the cooling effect is more than 1000K.
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이상수(S.S. Lee),김재수(J.S. Kim) 한국전산유체공학회 2009 한국전산유체공학회 학술대회논문집 Vol.2009 No.4
The present paper focuses on the analysis of aero-acoustics characteristic by several boundary conditions. In this simulation, a high-order and high-resolution numerical schemes are used for the accurate computation of compressible flow with several boundary conditions including characteristic boundary conditions as well as extrapolation and zonal characteristic boundary condition. These boundary conditions are applied to the computation of two dimensional circular cylinder flows with Mach number of 0.3 and Reynolds number of 400. The computation results are validated witht measurement datum and other computation results for the Strouhal frequency of vortex shedding, the mean drag coefficient and root-mean-square lift for the unsteady periodic flow regime. Secondary frequency is predicted by three kinds of boundary conditions characteristic.
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초음속난류유동장에서 후향계단 후류의 측면제트분사에 대한 수치적연구
김종록(J.R. Kim),김재수(J.S. Kim) 한국전산유체공학회 2002 한국전산유체공학회 학술대회논문집 Vol.2002 No.-
This paper describes numerical research on transverse jet behind rearward-facing step in turbulent supersonic flowfields without chemical reaction. The purpose of transverse jet behind rearward-facing step is to improve mixing of the fuel in the combustor. Two-dimensional unsteady flowfields generated by slot injection into supersonic flow are numerically simulated by integration of Navier-Stokes equation. Final-scale turbulence effects are modeled with two-equation k- E model. Numerical methods are modeled high-order upwind TVDschemes. A total of 4 cases are computed, comprising slot momentum flux ratios at four step heights downstream of the step. These numerical results are represented periodic phenomenon in unsteady flowfields.
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적응 격자계를 이용한 초음속 난류유동장의 측면제트분사에 대한 수치적연구
김종록(J.R. Kim),김익태(I.T. Kim),김재수(J.S. Kim) 한국전산유체공학회 2001 한국전산유체공학회지 Vol.6 No.2
Two-dimensional steady flowfields generated by slot injection into supersonic flow are numerically simulated by the integration of Navier-stokes equation with two-equation k-turbulence model. High-order upwind scheme is used on unstructured adaptive meshes. The numerical results are compared with experimental data in terms of surface static pressure distributions, the length of the upstream separation region, and the height of the Mach surface for steady flowfields with a Mach number of 3.71 and a unit Reynolds number of 5.83×10^6/m.
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문지수(J.S. Moon),김재수(J.S. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
Oscillating airfoil have been challenged for the dynamic stalls of airfoil and wind turbines at high angle of attach. Especially, the pressure oscillation has a huge effect on noise generation, structure damage, aerodynamic performance and safety, because the flow has strong unsteadiness at high angle of attack. In this paper, the unsteady aerodynamics coefficients were analyzed for the oscillating airfoil at high angle of attack around two dimensional NACA0012 airfoil. The two dimensional unsteady compressible Navier-Stokes equation with a LES turbulent model was calculated by OHOC (Optimized High-Order Compact) scheme. The flow conditions are Mach number of 0.2 and Reynolds number of 1.2×10⁴. The lift, drag pressure distribution, etc. are analyzed according to the pitching oscillation. Unsteady velocity field, periodic vortex shedding, the unsteady pressure distribution, and the acoustic fields are analyzed. The effects of these unsteady characteristics in the aerodynamic coefficients are analyzed.
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