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덕트 내부 형상이 무인기용 덕티드 팬의 성능에 미치는 영향
이광민(K.M. Lee),김철완(C.W. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.11
Ducted fans that are popular choices in Vertical take-off and landing (VTOL) unmanned aerial vehicles (UAV) offer a higher static thrust/power ratio for a given diameter than open propellers. Although ducted fans provide high performance in many UAV applications, there havent been well-studied on the internal shape of ducts. In the present study, the aerodynamic characteristics of the ducted fan composed a 34cm diameter duct and 5 blades investigated based on Reynolds-Averaged Navier-Stokes (RANS) and SST model. RANS prediction of thrust performance was compared to the wind tunnel test data. Comparison of internal duct shapes shows results affecting the overall performance of the ducted fan. As the depth of furrow on the duct and tip clearance change, the thrust performance also changes.
이광민(K.M. Lee),이융교(Y.K. Lee),김철완(C.W. Kim),안석민(S.M. Ahn) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11
This paper presents the computational aerodynamics analysis of a complete EAV(Electric Aerial Vehicle) configuration propeller rotating effect is applied. EAV-2H, being developed by KARI(Korea Aerospace Research Institute) is a technology demonstrator for HALE(High Altitude Long Endurance), solar energy and secondary battery is used to power this aircraft. Also it has been applied for long-endurance, high aspect ratio, low Reynolds airfoil. Computational analysis predicts the performance of the propeller and cruise power and it was verified by wind tunnel and flight tests.
기계적 합금법으로 제조된 Al-Nb 합금 및 Al-Al3Nb 복합재료 압출재의 인장 특성
김상식,박민우,정광철,안인섭,류영빈,이광민 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.12
Tensile behavior of mechanically alloyed(MA) Al-5 wt.%Nb alloy extrusion was examined at various temperatures and strain rates. The tensile ductility of MA Al-5wt.%Nb alloy extrusion was greatly reduced with increasing temperature and/or decreasing strain rate. The SEM observations of side and fracture surfaces of tensile fractured specimens demonstrated that the overall void density formed during deformation was considerably reduced, along with the sign of decreased plasticity around the dimples on the fracture surface. To understand the effect of grain size on the deformation behavior of submicron grain sized alloys, Al-5 vol. %Al₃Nb composite extrusions with different grain sizes were fabricated and tensile tested at different temperatures. The present study confirms that the reduction in tensile ductility of submicron grain sized alloys at elevated temperatures are undoubtedly related to the grain size. Fast dynamic recovery rates, due to the lack of dislocation substructures, in submicron grain sized alloys appears to be responsible for the elevated temperature reduction in tensile ductility.