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박영민(Y. M. Park),김철완(C. W. Kim),정진덕(J. D. Chung),이해창(H. C. Lee) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
A rotating propeller of turboprop aircraft gives much effect on the aerodynamic characteristics of wing such as lift, moment and stall. Specially, a rotating propeller changes the lift and moment characteristics when aircrafts are in landing or take-off condition. In the present paper, 3-dimensional Navier-Stokes simulations for the interaction of propeller and wing were carried out. For rotating propeller, unsteady sliding mesh method was used to simulate a relative motion. For the power effect analysis in landing and take off configurations, double slotted flap was also considered and the aerodynamic characteristics were investigated. It was shown that the propeller slipstream enhanced the lift slope including maximum lift and this enhancement was more dominant with high lift device.
3 레벨 인버터를 이용한 유도 전동기의 직접 토크 제어
박영민(Y.M. Park),이세현(S.H. Lee),윤재학(J.H. Yun),박영우(Y.W. Park),김남해(N.H. Kim),이교범(K.B. Lee),송중호(J.H Song) 전력전자학회 1999 전력전자학술대회 논문집 Vol.1999 No.7
In this paper a Direct Torque Control(DTC) scheme for PWM three level inverter-fed induction motor drives, is presented and discussed. In orde to deal with DTC scheme applied three level inverter, the selection of voltage vector is proposed to minimize switching frequency and torque ripple. The simulation results shows a validity of thi control scheme
박영민(Y. M. Park),강형민(H. M. Kang),정진덕(J. D. Chung),이해창(H. C. Lee) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5
Numerical optimization of two dimensional high lift configuration was performed with Navier-Stoles solver and Response Surface Method. For two dimensional flow analysis, Navier-Stokes solver with Spalart-Allmaras turbulence model was selected for the simulation of highly complex and separated flows near flap. In order to validate the current flow solver, NLR 7301 and Douglas 3 element airfoils were selected and the results were compared with experimental data. For optimization method, response surface model based on two dimensional CFD aerodynamic results was used. In order to optimize both flap shape and setting (gap/overlap) simultaneously, ten design variables (eight variables for flap shape variation and two variables for flap setting) were chosen for optimization. In order to construct response surface equation, 128 experimental points were selected for 10 design variables. For the investigation of both low and high angle of attack aerodynamics, angle of attack conditions from 0 to 16 degree were selected for numerical analysis. The objective function considering maximum lift coefficient, lift to drag ratio and lift coefficient at specific angle of attack was selected to reduce flow separation on the flap surface. The present method was applied to two dimensional fowler flap in landing configuration. After applying the present method, it was shown that the optimized high lift configuration has low flow separation on the flap surface and enhanced lift to drag ratio within entire angle of attack range
유동분배판에 의한 원통-다관형 열교환기의 성능 특성에 관한수치해석적 연구 전열특성(Ⅱ)
박영민(Y.M. Park),이태호(T.H. Lee),정희택(H.T. Chung),김형범(H.B. Kim) 한국전산유체공학회 2016 한국전산유체공학회지 Vol.21 No.4
In the previous study, it is proved by numerical simulation that the baffle shaped as the porous plate installed in the inlet chambers improves the redistribution of the flow injecting to the tube bundles. In the present study, numerical simulation has been performed to investigate the effects of the flow distributors on the thermal characteristics of the shell and tube heat exchangers. The flow fields have been analysed by the three-dimensional Navier-Stokes solvers including the thermal conditions on the shell sides. The numerical results showed that the presence of the baffles improves the redistribution of the heat transfer to the tube bundles though the overall performance drop slightly on the present flow conditions.
유동분배판에 의한 원통 다관형 열교환기의 성능 특성에 관한 수치해석적 연구(Ⅰ)
박영민(Y.M. Park),정희택(H.T. Chung),김형범(H.B. Kim) 한국전산유체공학회 2014 한국전산유체공학회지 Vol.19 No.3
The flow pattern inside the inlet chamber of the tube side is one of the key parameters influencing on the performances of the shell-and-tube type of heat exchangers(STHE). In order to improve the flow distribution, the baffle shaped as the porous plate is installed in the inlet chambers. In the present study, numerical simulation has been performed to investigate the flow features of the tube side of the STHE in sense of the hydraulic performances. The flow fields have been analysed by the three-dimensional Navier-Stokes solvers with the proper turbulent models. Computational domain is ranged in the whole of the tube side of the STHE. The numerical results showed that the presence of the baffles improves the redistribution of the flow injecting to the tube bundels. The good agreements of the numerical results with the experimental results of PIV measurements have been shown for the validation of the numerical methods adopted in the present papers.