• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.49-57
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• 2003

The flight trajectory of a boomerang is predicted with the momentum theory (actuating disk theory) and the blade element method generally used as tools to analyze in the rotary-wing aerodynamics. Boomerangs made by students are actually compared with the computational results, utilized to get the physical intuition. The transition from helicopter mode to autogyro mode with the gyroscopic precession is observed in numerical analysis and experiment like a 'flying rotor' after the boomerang taking off. The whole system is shown to be highly nonlinear and very sensitive to the initial conditions. Various flight loci may be obtained if we change the parameters.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.71-74
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• 2012

Generally, tone noise is generated at the rotary wing and helicopter. BVI(Blade-Vortex Interaction) noise is one of the helicopter's tone noise. The BVI noise is governed by tip-vortex characteristics such as vortex size, strength and trajectory. To avoid BVI, many methods have been developed and proposed. In this paper, rotating blade with active tab was numerically investigated to reduce BVI noise. For flow and noise simulation, the lifting surface approach and the acoustic analogy were used. Using numerical methods, the noise directivity and maximum noise position were predicted.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.120-124
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• 2007

Helicopters and rotary-wing vehicles encounter a wide variety of complex aerodynamic phenomena and these phenomena present substantial challenges for computational fluid dynamics(CFD) models. This investigation presents the rotor aerodynamic analysis items for the helicopter development and variety aerodynamic analysis methods to provide the better solution to researchers and helicopter developers between aerodynamic problems and numerical aerodynamic analysis methods. The numerical methods to make an analysis of helicopter rotor are as below - CFD Modelling : actuator disk model, BET model, fully rotor model,... - Grid : sliding mesh, chimera mesh / structure mesh, unstructure mesh,... - etc. : panel method periodic boundary, quasi-steady simulation, incompressible,... The choice of CFD methodology and the numerical resolution for the overall problem have been driven mostly by available computer speed and memory at any point in time. The combination of the knowledge of aerodynamic analysis items, available computing power and choice of CFD methods now allows the solution of a number of important rotorcraft aerodynamics design problems.