• Proceedings of the KSME Conference
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• 2001.06e
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• pp.367-372
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• 2001

The paper presents an improved way of aerodynamic quality in Korean Very High Speed Railway, The pantograph model being under development dissatisfies the required grade of aerodynamic lift force. So the present work proposes modified configurations of panheads to maintain consistent aerodynamic characteristics. Analysis has been performed using commercial CFD program. Simulation based analysis has been conducted with two different models. One is to attach the thin plate on the crossbar and the other is the use of trapezoidal cross section in contact strip. Various length of thin plate is simulated for flow velocity and acceptable value of plate length is selected which satisfy the necessary average lift force. Aerodynamic variation on the panheads strip is studied.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.43-53
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• 2006

Aerodynamic shape design of the Mid-sized Aerostat was performed with computational fluid dynamics. Design procedure included determination of hull volume and length, hull shape, tailfin configuration with anhedral and location, tailfin section. For aerodynamic analysis, three dimensional Navier-Stokes equations were applied with Spalart-Allmaras turbulence model. During design procedure, static moment derivatives were mainly considered for the stability of aerostat and structural limitations were also considered for practical application of the designed shape. Aerodynamic analysis of the designed aerostat was carried out and aerodynamic characteristics were compared with those of the TCOM 71m aerostat, one of the most successful commercial aerostats. It was found that the designed KARI Mid-sized Aerostat had better stability characteristics compared to the TCOM 71m aerostat.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.59.2-59.2
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• 2011

Although there are many activities on the construction of wind farm to produce amount of power from the wind, in practice power productions are not as much as its expected capabilities. This is because a lack of both the prediction of wind resources and the aerodynamic analysis on turbines with far wake effects. In far wake region, there are velocity deficits and increases of the turbulence intensity which lead to the power losses of the next turbine and the increases of dynamic loadings which could reduce system's life. The analysis on power losses and the increases of fatigue loadings in the wind farm is needed to prevent these unwanted consequences. Therefore, in this study velocity deficits have been predicted and aerodynamic analysis on turbines in the far wake is carried out from these velocity profiles. Ainslie's eddy viscosity wake model is adopted to determine a wake velocity and aerodynamic analysis on wind turbines is predicted by the numerical methods such as blade element momentum theory(BEMT) and vortex lattice method(VLM). The results show that velocity recovery is more rapid in the wake region with higher turbulence intensity. Since the velocity deficit is larger when the turbine has higher thrust coefficient, there is a huge aerodynamic power loss at the downstream turbine.

• Journal of Ocean Engineering and Technology
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• v.29 no.3
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• pp.255-262
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• 2015

The present study developed a numerical simulation tool for the coupled dynamic analysis of multiple turbines on a single floater (or Multiple Unit Floating Offshore Wind Turbine (MUFOWT)) in the time domain, considering the multiple-turbine aero-blade-tower dynamics and control, mooring dynamics, and platform motions. The numerical tool developed in this study was designed based on and extended from the single-turbine analysis tool FAST to make it suitable for multiple turbines. For the hydrodynamic loadings of floating platform and mooring-line dynamics, the CHARM3D program developed by the authors was incorporated. Thus, the coupled dynamic behavior of a floating base with multiple turbines and mooring lines can be simulated in the time domain. To investigate the effect of asymmetric aerodynamic loading on the global performance and mooring line tensions of the MUFOWT, one turbine failure case with a fully feathered blade pitch angle was simulated and checked. The aerodynamic interference between adjacent turbines, including the wake effect, was not considered in this study to more clearly demonstrate the influence of the asymmetric aerodynamic loading on the MUFOWT. The analysis shows that the unbalanced aerodynamic loading from one turbine in MUFOWT may induce appreciable changes in the performance of the floating platform and mooring system.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.180.2-180.2
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• 2010

Simulation technology for dynamic analysis of wind turbine is developed. The Aerodyn and the DAFUL are chosen for aerodynamic analysis and multi-body and flexible body dynamics respectively. Subroutines and variables of Aerodyn developed by NREL are analyzed with hub-height wind data, full field turbulent wind data and Airfoil data. The interface to perform coupled analysis between AeroDyn and DAFUL, GUI for modeling several parts of wind turbines are developed. The program will be extended to analyze the coupled analysis of aerodynamic and hydrodynamic behavior for floating offshore wind turbines.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.6
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• pp.1590-1597
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• 1994

The aerodynamic analysis of a $6{\times}6$ counter-rotating propfan around a missile-like-body has been completed analytically using a frequency domain panel method. The present method requires Fourier transformation of flow field around the propfan in computing the velocities normal to the propfan lifting surfaces. The aerodynamic performance curve is determined by angle of attack and nonuniform inflow conditions. The inflow conditions result from the variations of missile flight speed, angle of attack, propfan location relative to control surfaces and control surface deflection angle. The two cases of propfan location relative to control surface, front and behind, are analyzed and the aerodynamic results are presented.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.19 no.2
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• pp.85-88
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• 2008

Several parameters are used for the assessment of phonatory function and voice quality in clinical settings. Glottic airflow, subglottal pressure, mean phonation time, laryngeal resistance and voice efficiency are the most commonly used aerodynamic parameters. Aerodynamic analysis is developed to evaluate phonatory energy source and to estimate laryngeal efficiency. Also these measurements have shown the good correlation with perceptions of breathiness and findings of glottic competence. Aerodynamic study is important to understand relationships between pulmonary and phonatory function.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.3 s.18
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• pp.21-29
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• 2004

Numerical analysis of aerodynamic heating for KPSAM is performed using aerodynamic heating model suitable to KPSAM, which has complex flow field resulting from the spike attached to the dome, such as large separation area and the strong shock/boundary layer interaction region around reattachment point on the dome. The aerodynamic heating model is validated and modified through the comparison between the flight test measurement and the thermal analysis results. TFD temperature sensors are installed on the dome to measure surface temperature during the flight. Computation results, obtained from the heat transfer analysis on the sensors, agree well with flight test data. The aerodynamic heating model provides heat transfer rate into surface as a boundary condition of unsteady 1D/axisymmetric thermal analysis on the missile structure. The axisymmetric thermal analysis using FLUENT is more versatile than the 1D analysis and can be applied to the heating problem related with complex structures and multi-dimensional heat transfer problems such as prediction of temperature rise at contact surface of different materials.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.21-30
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• 2005

The aerodynamic analysis of helicopter rotor airfoils was performed to generate the basic data for selection and distribution of airfoils at the helicopter rotor blade preliminary design phase.10 airfoils were chosen among the existing rotor airfoils, and the tabulated aerodynamic coefficients which are proper for the aerodynamic analysis using blade element theory were generated. Considering analysis cost, the simple mathematical models were chosen before the wind tunnel test to generate the aerodynamic characteristic curves($C_{l},C_{m},C_{d}$) in full AoA range($-180^{o}\sim180^{o}$) including the reverse flow region. The essential data necessary to the generation of the complete curves were obtained by using the IBLM(Interactive Boundary Layer Method). The generated aerodynamic characteristic curves agree with experimental results qualitatively. Finally, the aerodynamic characteristics of all 10 airfoils were compared and classified according to their own lift or moment characteristics.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.516-520
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• 2009

This study describes aerodynamic characteristics for the HAWT (Horizontal Axis Wind Turbine) rotor blade using general CFD(Computational Fluid Dynamics) code. The boundary conditions for analysis are validated with the experimental result by the NREL (National Renewable Energy Laboratory)/NASA Ames wind tunnel test for S809 airfoil. In the case of wind turbine rotor blade, complex phenomena are appeared such as flow separation and re-attachment. Those are handled by using a commercial flow analysis tool. The 2-equation k-$\omega$ SST turbulence model and transition model appear to be well suited for the prediction. The 3-dimensional phenomena in the HAWT rotor blade is simulated by a commercial 3-D aerodynamic analysis tool. Tip vortex geometry and Radial direction flows along the blade are checked by the analysis.