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프로펠러와 고양력 장치와의 공력간섭에 대한 수치해석 연구
박영민(Y. M. Park),김철완(C. W. Kim),정진덕(J. D. Chung),이해창(H. C. Lee) 한국전산유체공학회 2011 한국전산유체공학회지 Vol.16 No.4
A rotating propeller of turboprop aircraft gives much effect on the aerodynamic characteristics of wing such as lift, moment and stall. Specially propeller effect on the wing surface is much more dominant when aircrafts are in landing or take-off conditions. In the present paper, three dimensional Navier-Stokes simulations for the interaction of propeller and wing were carried out for medium sized turboprop aircraft. For rotating propeller, unsteady sliding mesh method was used to simulate a relative motion between moving and static bodies. 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 by eliminating local flow separation region and this enhancement was more dominant with high lift device.
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.
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
박영민(Y.M. Park),정진덕(J.D. Chung),이해창(H.C. Lee) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5
The recent development of CFD technologies and computing resources enables high fidelity aircraft analysis and designs in even conceptual and preliminary design process. More and more, these high fidelity analysis are replacing the high cost wind tunnel tests and contributes to the reduction of entire aircraft design period. In the present paper, examples of CFD applications in KARI(Korea Aerospace Research Institute) are introduced especially for fixed wing aircraft such as turboprop. In KARI, most of CFD processes are mainly used for analysis and design of aircraft. The most basic approaches is for the design of two dimensional airfoil and high lift devices using Navier-Stokes solver. For the three dimensional wing analysis such as wing planform study, high lift device, Navier-Stokes simulations are also commonly used for low and high speed aerodynamic analysis. In order to analyze the effect of rotating propeller effect, unsteady Navier-Stokes simulations using sliding mesh technique are used for the relative motion. In the present paper, various applications of CFD in KARI for fixed wing aircraft design are introduced from two-dimensional high lift device design to rotating propeller effect including high lift device.
이해무,윤기봉,신규인,최현창,박재학 한국산업안전학회 1997 한국안전학회지 Vol.12 No.2
Fracture behavior of ex-serviced 1Cr-0.5Mo steel was measured at room(24℃) and elevated(538℃) temperature and compared with that measured with virgin 1Cr-0.5Mo steel. Compact C(T) specimens were machined from the base and welded test materials. In case of the C(T) specimens of the weld, fatigue precrack was introduced along the fusion line so that following crack growth should occurs along the region of heat affected zone. It was observed that the J-R curve of the serviced material was significantly lower than that of the virgin material at room temperature. Brittle fracture was observed in the serviced material. On the other hand, at elevated temperature no noticeable difference was found between the J-R curves of the virgin and the serviced material. The measured J-R curves were also compared with those of the 1.25Cr-0.5Mo steel obtained from the other literatures. Optical microscopy and SEM examination of the serviced material reveal the carbide in/along the grain boundary which shows material degradation due to long-term usage. An example of application of the measured J-R curves is shown.