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강희정(H.J. Kang),김도형(D.H. Kim),김승호(S.H. Kim) 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.3
Numerical simulation was performed for the rotor blade with fixed tab in hover using an unstructured mesh Navier-Stokes flow solver. The inflow and outflow boundary conditions using 1D momentum and 3D sink theory were applied to reduce computational time. Calculations were performed at several operating conditions of varying collective pitch angle and fixed tab length. The aerodynamic effect of fixed tab length was investigated for hovering efficiency, pitching moment and flapping moment of the rotor blade. The results show that it affects linearly increasing on the pitching moment of the rotor blade but does not affect on the flapping moment. The required power is less than 45kw for ground rotating test in hover. Numerical simulations also show that the vortex generate not only from the tip of the rotor blade but also from the fixed tab on the rotor blade.
위상차를 가지고 회전하는 두 프롭의 공기역학적 상호작용에 대한 수치 해석
강희정(H.J. Kang) 한국전산유체공학회 2021 한국전산유체공학회지 Vol.26 No.3
Aerodynamic interaction of two props rotating with different phase angles was investigated using the computational fluid dynamics methodology. The separation distance between the two props with two-blade is d/R=0.1471 and the phase angle difference consists from –75 degrees to +90 degrees. The aerodynamic interaction of the two props resulted in oscillating unsteady aerodynamic loads. The average thrust of each prop was lower than that of a single prop, and the average torque was almost the same as that of a single prop. The average value and the minimum value of the oscillating thrust showed opposite tendencies between the two props according to the phase angle difference, but in the case of torque, the effect was relatively insignificant. It was also found that the aerodynamic load had the minimum value at the position where the blades of the two props were closest to each other. The sum of the aerodynamic loads of the two props was shown in the form of 2/rev and 4/rev depending on the phase angle difference between the two props, and the amplitude became maximum as the relative phase angle difference between the two props is closer to 0 degree, and minimum as it approaches 90 degrees. In the comparison of the velocity field, there were found that the aerodynamic interaction of the two props had an asymmetric velocity field unlike the case of a single prop and the center of the wake had shifted towards each other.
CFD-CSD 연계 기법을 이용한 로터 블레이드 공력 및 소음 해석
강희정(H.J. Kang),김도형(D.H. Kim),위성용(S.Y. Wie) 한국전산유체공학회 2014 한국전산유체공학회지 Vol.19 No.3
The aerodynamic and noise calculations were performed through the CFD-CSD loose coupling methodology. In the loose coupling process, the trimmed rotor airloads were predicted by the in-house CFD code based on unstructured overset meshes, and the trim of the rotorcraft and the aeroelastic deformation of rotor blades were accounted with the CAMRAD Ⅱ rotorcraft comprehensive code. The set of codes was used to analyze the HART-Ⅱ baseline test condition. The effect of grid resolution and time step was examined and the loose coupling approach was found to be stable and convergent for the case. Comparison of the resulting sectional airloads, structural deformations, the noise carpets and the wake geometry with experimentally measured data was presented and showed the good agreement.
강희정(H.J. Kang),김도형(D.H. Kim),김승호(S.H. Kim) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5
Numerical simulation was performed for the rotor blade with fixed tab in hover using an unstructured mesh Navier-Stokes flow solver. The inflow and outflow boundary conditions using 1D momentum and 3D sink theory were applied to reduce computational time. Calculations were performed at several operating conditions of varying collective pitch angle and fixed tab length. The aerodynamic effect of fixed tab length was investigated for hovering efficiency, pitching moment and flapping moment of the rotor blade. The results show that it affects linearly increasing on the pitching moment of the rotor blade but does not affect on the flapping moment. The required power is less than 45kw for ground rotating test in hover. Numerical simulations also show that the vortex generate not only from the tip of the rotor blade but also from the fixed tab on the rotor blade.
두 프롭 간의 이격 거리에 대한 제자리 비행 시 공기역학적 상호작용 수치 해석
강희정(H.J. Kang) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.3
Aerodynamic interactions according to the separation distance between two props were investigated using the computational fluid dynamics methodology. Numerical analysis was performed for two shapes, two-bladed props and three-bladed props. Unsteady aerodynamic load occurred due to the interaction of the two props, and the fluctuation of unsteady load increased dramatically as the separation distance decreased. The thrust was compared with the experimental results of other researchers, and as the separation distance increased, the tendency to approach the thrust of a single prop was found to be consistent. It was also found that the torque increased than that of a single prop, but the effect of the separation distance was relatively insignificant. In the comparison of the flow field, it was found that the aerodynamic interaction of the two props has an asymmetric velocity field unlike the case of a single prop.
강희정(H.J. Kang),김승호(S.H. Kim),주진(G. Joo),안이기(I.K. Ahn) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.5
Computational fluid dynamic(CFD) analysis is a powerful, cost-effective tool for the study of the aerodynamic characteristics of a flow. In this paper, applications of CFD in the analysis of rotorcraft were introduced. A three-dimensional flow solver based on unstructured meshes was used for the simulation and an overset mesh technique was applied to handle the relative motion between the main rotor and other components. The aerodynamic performance characteristics of a shrouded tail rotor and main rotor blade with vane tip was investigated. Unsteady flow simulations of a complete helicopter configuration were conducted and the aerodynamic interferences among main rotor, fuselage and tail rotor were investigated. A numerical study for the ground effect of a whirl tower rotor system and the drag prediction of a bearingless rotor hub were also performed.