• Proceedings of the KIEE Conference
• /
• 2003.07d
• /
• pp.2268-2270
• /
• 2003

In this paper, mathematically modeled equations were derived for wind turbine under the analysis of aerodynamics. On the basis of these equations, maximum power controller is implemented by simulink in matlab. In order to achieving maximum power, variable speed control method is used for obtaining maximum power coefficient in the variable wind speed because we can have maximum changing efficiency in these coefficients. Also, the maximum power control of wind generator system uses a synchronous generator and a invertor circuit.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.06a
• /
• pp.273-276
• /
• 2006

To generate electricity from wind energy, wind turbine generally has a rotor blade. Since this rotor blade is a kind of the rotating machinery, the wake from the rotor is very Important role in the side of the aerodynamic performances. Thus the study about wake is essential to analyze wind turbine aerodynamics. In this study wake characteristics are analyzed by hot-wire probe in the K.A.F.A(Korea Air Force Academy) wind tunnel. It is possible to analyze the wake characteristics by hot-wire probe from acquiring the velocity fluctuations at given positions in the flow. This velocity data are arranged by trigger signal at same azimuth of the blade in periodic manner of the rotor blade. From this various wake characteristics are found : radial and axial position of the tip vortex, vortex core characteristics in the flow etc.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.1207-1214
• /
• 2001

The paper deals with the computational approach in analysis and design of pantograph panhead strips of high-speed railway in aerodynamic and aeroacoustic concerns. Pantograph is an equipment such that the electric power is supplied from catenary system to train. Due to the nature of complexity in high-speed fluid flow, turbulence and downstream vortices result in the instability in the aerodynamic contact between panhead strips and catenary system, and consequently generate the considerable levels of flow-induced sound. In this paper, based on the preceding low speed wind-tunnel test and simulations, the aerodynamic and aeroacoustic characteristics in low speed are analyzed.

• Research in Mathematical Education
• /
• v.22 no.2
• /
• pp.83-97
• /
• 2019

Science, Technology, Engineering, and Mathematics (STEM) education has been at the forefront of K-12 curricula in the technology-rich 21st century, with emphasis on how these fields reinforce each other in preparing students for a dynamic future. However, there is a need for greater attention to STEM education research in the mathematics education community, in particular to pedagogical approaches that facilitate integrating the mathematics component of STEM education. Toward this end, the authors report the outcomes of a Project-based Learning (PBL) unit in which upper elementary students integrated STEM elements by researching, crafting, testing, and evaluating kites they created by applying scientific knowledge of aerodynamics and mathematical knowledge of polygons, surface area, graphs, and data analysis. This unit, which the authors developed, implemented, and assessed, demonstrates how STEM subjects and in particular mathematics can be effectively integrated in upper elementary school classrooms through PBL.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.5
• /
• pp.53-60
• /
• 2022

In this study, the conceptual design and performance evaluation of a personal air vehicle (PAV) is presented, which is a potential futuristic individual transportation. The blade element theory (BET) is employed to compute a rotational velocity. A computational fluid dynamics (CFD) simulation is performed to investigate the difference in the thrust performance in the rotor axis distance of a quad-copter PAV in hovering. Modal analysis is performed to create a Campbell diagram to investigate critical speed. Consequently, a quad-copter PAV changes the aerodynamics thrust and critical velocity according to the rotor axis distance.

• Journal of the Korean Society of Visualization
• /
• v.21 no.2
• /
• pp.8-13
• /
• 2023

The primary challenge in improving fuel efficiency and reducing air pollution for commercial vehicles is reducing their aerodynamic drag. Various flow control devices, such as cab-roof fairing, gap fairing, cab extender, and side skirt have been introduced to reduce drag, however, the drag reduction effect and applicability are different depending on each commercial vehicle model. To evaluate the fuel consumption of heavy vehicles, a comprehensive research approach, including drag force measurement, flow field analysis is required. This study investigated the effect of a cab extender, which installed rear region of cab, on a drag coefficient of commercial vehicle through wind tunnel experiments and CFD. The results showed that the cab extender significantly modified the flow structure around the vehicle, leading to 8.2% reduction in drag coefficient compared to the original vehicle model. These results would provide practical application for enhancing the aerodynamic performance and fuel efficiency of heavy vehicle.

• Journal of Wind Energy
• /
• v.5 no.1
• /
• pp.33-42
• /
• 2014

The new aerofoil, KA2 was designed to apply to the wind turbine blade. For the aerofoil, numerical analysis was performed to review aerodynamic characteristics like lift and drag coefficient. And they are verified with test data using the digital wind tunnel and test samples from 3D printer. The digital wind tunnel was developed to test wing in the small laboratory, and verified with test of NACA0012 airfoil. KA2 aerofoil is asymmetric, and has the thickness ratio of 14%, and 12 degree of AOA at the maximum lift coefficient of 1.3. In this paper, aerodynamic characteristics from numerical and test approaches will be proposed with AOA in detail. Therefore, this aerofoil will be used for the design of wind turbine blade.

• Advances in aircraft and spacecraft science
• /
• v.9 no.4
• /
• pp.319-333
• /
• 2022

This work presents a numerical investigation of the aerodynamics and aero acoustics of the HVAB rotor in hover conditions. Two fully turbulent models are employed, the one-equation Spalart-Allmaras model and the two-equation k-ω SST model. Transition effects are investigated as well using the Langtry-Menter γ-Re θt transition transport model. The noise generation and propagation are being investigated using the Ffows-Williams Hawking model for far-field noise and the broadband model for near-field noise. Comparisons with other numerical solvers and with the PSP rotor test data are presented. The results are presented in terms of thrust and power coefficients, the figure of merit, surface pressure distribution, and Sound pressure level. Velocity, pressure, and vortex structures generated by the rotor are also shown in this work. In addition, this work investigates the contribution of different blade regions to the overall noise levels and emphasizes the importance of considering specific areas for future improvements.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.11b
• /
• pp.914-920
• /
• 2002

Nonlinear flow-induced vibration characteristics of a generic missile wing (or control surface) are investigated in this study. The wing model has freeplay structural nonlinearity at its pitch axis. Nonlinear aerodynamic flows with unsteady shock waves are considered in the transonic flow region. To practically consider the effects of freeplay structural nonlinearity, the fictitious mass method (FMM) is applied to structural vibration analysis based on a finite element method (FEM). A computational fluid dynamics (CFD) technique is used for computing the nonlinear unsteady aerodynamics of all-movable wings. The aerodynamic analysis is based on the efficient transonic small-disturbance aerodynamic equations of motion using the potential-flow theory. To solve the nonlinear aeroelastic governing equations including the freeplay effect, a modal-based computational structural dynamic (CSD) analysis technique based on fictitious mass method (FMM) is used in time-domain. In addition, CSD and unsteady CFD techniques are simultaneously coupled to give accurate computational results. Various aeroelastic computations have been performed for a generic missile wing model. Linear and nonlinear aeroelastic computations have been conducted and the characteristics of flow-induced vibration are introduced.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.1
• /
• pp.86-91
• /
• 2008

An integrated multidisciplinary analysis and design system plays a critical role in the preliminary design of an aircraft. In this work a system based on the CATIA is developed for multidisciplinary computational design; aerodynamics, elasticity, and radar frequency stealth. Common data base of geometry and rectangular grids is generated and used for aerodynamic and structural analysis, while derivative triangular grids are generated for the RCS calculation. The panel method (PANAIR), FEM (NASTRAN), and PO technique are used for aerodynamic, structural, and RF stealth computations, respectively, and several additional algorithms are developed for the effective communication of the common data.