• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.277-280
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• 2006

This paper describes the aerodynamic interference characteristics between the ing and the engines in a commercial airplane which is realized by reverse engineering based on the photo measurement. Steady three-dimensional compressible inviscid Euler equation is solved in the unstructured grid system under the cruise condition. The lift and drag forces in the wing with engines increase by 1.49% and 3.9%, respectively compared with the wing without engines.

• Wind and Structures
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• v.5 no.6
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• pp.479-492
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• 2002

A finite element aerodynamic model that can be used to analyse flutter instability of long span bridges in the time domain is presented. This approach adopts a simplified quasi-steady formulation of the wind forces neglecting the vortex shedding effects. The governing equations used are effective only for reduced velocities $V^*$ sufficiently great: this is generally acceptable for long-span suspension bridges and, then, the dependence of the wind forces expressions of the flutter derivatives can be neglected. The procedure describes the mechanical response in an accurate way, taking into account the non-linear geometry effects (large displacements and large strains) and considering also the compressed locked coil strands instability. The time-dependence of the inertia force due to fluid structure interaction is not considered. The numerical examples are performed on the three-dimensional finite element model of the Great Belt East Bridge (DK). A mode frequency analysis is carried out to validate the model and the results show good agreement with the experimental measurements of the full bridge aeroelastic model in the wind tunnel tests. Significant parameters affecting bridge response are introduced and accurately investigated.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.48-53
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• 2001

A centrifugal fan design code was developed and included in $DasignFan^{TM}$. This program generates forward -curved and backward-curved bladed centrifugal fan data. With the inverse design concept used in the code, the period of designing a fm, which has given aerodynamic performance with minimal acoustic noise, is significantly shortened.. A centrifugal fan design code, developed in this study and included in $DasignFan^{TM}$, predicts the aerodynamic performance by using mean-line analysis and various loss models. In the period of design a lift force distribution between pressure side and suction side of blade is calculated. And then it is used to calculate steady loading noise from the impeller.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.87-90
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• 2002

Computational study has been undertaken to investigate the aerodynamic influence of side jet on a supersonic missile and to find a similarity condition between the flight condition and the wind tunnel testing. Tasks were performed to validate the existing Raytheon test body with side jet, to simulate the flow inside the supersonic wind tunnel, and to compare the flow fields between the missile in free flight and that in the wind tunnel. Then sub-scale model of body-tail configuration was analyzed to estimate the influence of the side jet on the missile components. It Is found that the influence of side Jet is not as significant on the tail region as on the body surface and a simple algebraic formula for aerodynamic coefficients accounting for the side jet as a point force may be cautiously utilized in setting up control logic.

• Journal of KSNVE
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• v.9 no.1
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• pp.113-120
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• 1999

A perforated tube nozzle as an exhaust noise suppressor of a high-speed civil transport(HSCT) is proposed. The experimental results for the near and far field sound. the visualization of jet structures and the static pressure distributions in the jet passing through a perforated tube are presented and discussed in comparison with those for a simple tube. It is shown that the perforated tube has an excellent performance to greatly reduce the shock-associated noise and that also the turbulent mixing noise is reduced in the range of a limited jet pressure ratio. This considerable noise reduction is due to the pressure relief caused by the through-flow through the perforated holes. Such a pressure relief results in the transformation of normal shock waves into weak Mach waves of X -type and increases the thrust force of the perforated tube nozzle.

• Wind and Structures
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• v.27 no.2
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• pp.89-100
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• 2018

3D simulations based on an impinging jet were carried out to investigate the flow field of a steady downburst and its effects on a high-rise building by applying the SST k-${\omega}$ turbulence model. The vertical profile of radial wind speed obtained from the simulation was compared with experimental data and empirical models in order to validate the accuracy of the present numerical method. Then wind profiles and the influence of jet velocity and jet height were investigated. Focusing on a high-rise building, the flow structures around the building, pressure distributions on the building surfaces and aerodynamic forces were analyzed in order to enhance the understanding of wind load characteristics on a high-rise building immersed in a downburst.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.288-294
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• 2010

In recent years, wind energy has been the world's fastest growing source of energy. This paper describes the structural design and analysis of composite blade for 2 kW-level HAWT (horizontal axis wind turbine). The aerodynamic design and force, which are required to design and analyze a composite blade structurally, are calculated through BEMT(blade element momentum theory) implemented in public code PROPID. To obtain the equivalent material properties of filament wound composite blades, the rule-of-mixture is applied using the basic material properties of fiber and matrix, respectively. Lay-up sequence, ply thickness and ply angle are designed to satisfy the loading conditions. Structural analysis by using commercial software ABAQUS is performed to compute the displacement and strength ratio of filament wound composite blades.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.42.1-42.1
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• 2011

NREL NWTC Deside codes are analyzed and introduced to develop the system performance simulation program for wind turbine generator systems. In this paper, The FAST performing multi-body and flexible body dynamics, control and the AeroDyn calculating aerodynamic forces with airfoil data and wind data are explained. Furthermore, initialization and process for transfer of aerodynamic force between AeroDyn and FAST at each time step are also introduced.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.99-105
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• 2006

In this study, nonlinear static and dynamic aeroelastic analyses for a high-aspect-ratio wing have been performed. To achieve these aims, the transonic small disturbance (TSD) theory for the aerodynamic analysis and the large deflection beam theory considering a geometrical nonlinearity for the structural analysis are applied, respectively. For the coupling between fluid and structure, the transformation of a displacement from the structural mesh to the aerodynamic grid is performed by a shape function which is used for the finite element and the inverse transformation of force by work equivalent load method. To validate the current method, the present analysis results of a high-aspect-ratio wing are compared with the experimental results. Static deformations in the vertical and torsional directions caused by an angle of attack and gravity loading are compared with experimental results. Also, static and dynamic aeroelastic characteristics are investigated. The comparisons of the flutter speed and frequency between a linear and nonlinear analysis are presented.

• 한국전산유체공학회:학술대회논문집
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• 2002.05a
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• pp.41-46
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• 2002

Computational study has been undertaken to investigate the aerodynamic influence of side jet on a supersonic missile and to find a similarity condition between the flight condition and the wind tunnel testing. Tasks were peformed to validate the existing Raytheon test body with side jet, to simulate the flow inside the supersonic wind tunnel, and to compare the flow fields between the missile in free flight and that in the wind tunnel. Then sub-scale model of body-tail configuration was analyzed to estimate the influence of the side jet on the missile components. It is found that the influence of side jet is not as significant on the tail region as on the body surface and a simple algebraic formula for aerodynamic coefficients accounting for the side jet as a point force may be cautiously utilized in setting up control logic.