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RISS 인기검색어
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- 저자 : 사정환(J.H. Sa) (검색결과 23 건)
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HART Ⅱ 로터-동체 모델의 CFD/CSD 연계해석과 동체효과 분석
사정환(J.H. Sa),유영현(Y.H. You),박재상(J.S. Park),박수형(S.H. Park),정성남(S.N. Jung),유영훈(Y.H. Yu) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
A loosely coupling method is adopted to combine a computational fluid dynamics (CFD) solver and the comprehensive structural dynamics (CSD) code, CAMRAD Ⅱ, in a systematic manner to correlate the airloads, vortex trajectories, blade motions, and structural loads of the HART Ⅱ rotor in descending flight condition. A three-dimensional compressible Navier-Stokes solver, KFLOW, using chimera overlapped grids has been used to simulate unsteady flow phenomena over helicopter rotor blades. The number of grids used in the CFD computation is about 24 million for the isolated rotor and about 37.6 million for the rotor-fuselage configuration while keeping the background grid spacing identical as 10% blade chord length. The prediction of blade airloads is compared with the experimental data. The current method predicts reasonably well the BVI phenomena of blade airloads. The vortices generated from the fuselage have an influence on airloads in the 1st and 4th quadrants of rotor disk. It appeared that presence of the pylon cylinder resulted in complex turbulent flow field behind the hub center.
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사정환(J.H. Sa),박수형(S.H. Park),김창주(C.-J. Kim),윤철용(C.Y. Yun),김승호(S.-H. Kim),김상호(S. Kim),유영훈(Y.H. Yu) 한국전산유체공학회 2009 한국전산유체공학회지 Vol.14 No.2
Numerical optimization of rotor blade airfoils is performed with a response surface method for helicopter rotor. For the baseline airfoils. OA 312, OA 309, and OA 407 airfoils are selected and optimized to improve aerodynamic performance. Aerodynamic coefficients required for the response surface method are obtained by using Navier-Stokes solver with k-w Shear Stress Transport turbulence model. An optimized airfoil has increased drag divergence Mach number. The present design optimization method can generate an optimized airfoil with multiple design constraints, whenever it is designed from different baseline airfoils at the same design condition.
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사정환(J.H. Sa),전상언(S.E. Jeon),박수형(S.H. Park) 한국전산유체공학회 2014 한국전산유체공학회지 Vol.19 No.2
Two-dimensional prediction capability of several analysis codes, such as XFOIL, MSES, and KFLOW, is compared and analyzed based on computational results of airfoil flows. To this end the transition transport equations are coupled with the Navier-Stokes equations for the prediction of the natural transition and the separation-induced transition. Experimental data of aerodynamic coefficients are used for comparison with numerical results for the transitional flows. Numerical predictions using the transition transport model show a good agreement with experimental data. Discrepancies have been found in the prediction of the pressure drag are mainly caused by the difference in the far-field circulation correction methods.
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사정환(J.H. Sa),박수형(S.H. Park),김창주(C.J. Kim),강희정(H.J. Kang),김승범(S.B. Kim),김승호(S.H. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.11
In this work, a comparative study is performed for simulation of rotor in hovering flight with a 3D compressible Navier-Stokes solver using overlapped grid systems. The shape of rotor blade consists of optimized rotor blade planforms. Optimized blade planforms are designed considering high performance on hovering and forward flight. To show the verification of optimized rotor blade planforms, blade loading(C<SUB>T</SUB>, FM, C<SUB>Q</SUB>) and the vortex behavior of optimized blade shape are compared with original blade shape.
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개선된 천이 전달 방정식을 사용한 3차원 천이 유동해석
사정환(J. H. Sa),전상언(S. E. Jeon),박수형(S. H. Park),정경진(K. J. Jung) 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.5
The crossflow effect was considered on crossflow transition. The original γ-Re<SUB>θ</SUB> transition model was applicable 3 dimension transition analysis, but this transition model was not enough considering crossflow effect. In the present study, improved transition transport equation was developed for simulating 3 dimension crossflow transition phenomena in infinite swept wing configuration. The experimental data using infinite swept wing were used for comparison with numerical results for crossflow transitional flow. The infinite swept wing consisted of NLF(2)-0145 airfoil and 45° sweep angle. The swept wing was tested at ?4° angle of attack and Reynolds numbers from 1.92×10<SUP>6</SUP> to 3.73×10<SUP>6</SUP>. The measured transition locations compared remarkably well with computations using improved transition transport equation for all investigated flow cases.
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고받음각 델타익 유동의 와류 붕괴 모사를 위한 DES 해석
사정환(J.H. Sa),손미소(M. Son),박수형(S.H. Park),구기범(G. Gu),김민아(M. Kim),정경진(K.J. Jung) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5
Detached Eddy Simulation(DES) is performed to understand vortex breakdown of a high-angle-of-attack Delta Wing flow. The fifth-order Upwind method is used to reduce turbulent dissipation. The computational results(DES) on ONERA Delta Wing model with a 70° sweep angle are compared with unsteady Reynolds-averaged Navier-Stokes(RANS) results and experimental data for validation with pressure distribution, surface pressure coefficient contour, and streamline distribution.
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