• International Journal of Aeronautical and Space Sciences
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• v.4 no.1
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• pp.45-52
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• 2003

A three-dimensional aerodynamic shape optimization technique in inviscid compressible flows is developed by using a parallel continuous adjoint formulation on unstructured meshes. A new surface mesh modification method is proposed to overcome difficulties related to patch-level remeshing for unstructured meshes, and the effect of design sections on aerodynamic shape optimization is examined. Applications are made to three-dimensional wave drag minimization problems including an ONERA M6 wing and the EGLIN wing-pylon-store configuration. The results show that the present method is robust and highly efficient for the shape optimization of aerodynamic configurations, independent of the number of design variables used.

• Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.46-50
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• 2008

Aerodynamic characteristics, such as drag and lift, play an important role in automobile design under certain speed conditions. Such characteristics are essential to design an automobile since they are directly related to automobile's performance such as passenger safety and fuel consumption. There is a huge demand for the automobile to have safe performance at high speed. Reduction in drag is also important and it could lead to the solution of air flow induced noise and dust problems. The objective of this research is to find out the aerodynamic differences between conventional side mirror and a modified one using CFD. Although drag generated around a side mirror is only about 7% of the total drag when a car runs, it is very closely related to driver's field of vision and noise generation. CFD simulation of the flowfield around a car side-view mirror was performed using a commercial code; Gambit and FLUENT.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.7
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• pp.800-808
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• 2004

Wind tunnel test of an airplane model with forward swept wing was done in KARI LSWT to evaluate and measure the aerodynamic characteristics of initially designed configuration. Since the given wing planform did not fully satisfy the design requirements, local flow control devices such as vortilon, vortex generator and flow fence were used to delay separation and to enhance aerodynamic characteristics. Also decision making processes of design parameters such as vertical tail boom length, the location, size and the incidence angle of horizontal tail were discussed. The general aerodynamic characteristics of forward swept wing for various control surface deflection conditions of flap, aileron and elevator were also given.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.100-110
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• 2007

A new design approach for a delicate treatment of complex geometries such as a wing/body configuration is arranged using overset mesh technique under large scale computing environment for turbulent viscous flow. Various pre- and post-processing techniques which are required of overset flow analysis and sensitivity analysis codes are discussed for design optimization problems based on gradient based optimization method (GBOM). The overset flow analysis code is validated by comparing with the experimental data of a wing/body configuration (DLR-F4) from the 1st Drag Prediction Workshop (DPW-I). In order to examine the applicability of the present design tools, careful design works for the drag minimization problem of a wing/body configuration are carried out by using the developed aerodynamic shape optimization tools for the viscous flow over multiple-body aircraft geometries.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.78-82
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• 2010

An integrated multi-disciplinary design system plays a critical role in the preliminary design of an aircraft. In this paper such system is developed for the multi-disciplinary computation and design; aerodynamics elasticity, and radio frequency stealth. Common data base of geometry and structured grids is generated and used for aerodynamic, structural and eletromagnetics analysis. The Navier-Stokes CFD, FEM, and CEM technique are used for aerodynamic, structural, and RF stealth computations respectively.

• Advances in aircraft and spacecraft science
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• v.8 no.4
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• pp.331-344
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• 2021

Airframe internal and external specifications are the product of intensive intellectual efforts and technological breakthroughs distinguishing each aircraft manufacturer. Therefore, geometrical information characterizing aircraft primary aerodynamic surfaces remain classified. When attempting to model real aircraft, many members of the aeronautical community depend on their personal expertise and generic design principles to bypass the confidentiality obstacles and sketch real aircraft airfoils, which therefore vary for the same aircraft due to the different designers' initial assumptions. This paper presents a photogrammetric shape prediction method for deriving geometrical properties of real aircraft airframe by utilizing their publicly accessible static and dynamic visual content. The method is based on extracting the visually distinguishable curves at the fairing regions between aerodynamic surfaces and fuselage. Two case studies on B-29 and B-737 are presented showing how to approximate the sectional coordinates of their wing inboard airfoils and proving the good agreement between the geometrical and aerodynamic properties of the replicated airfoils to their original versions. Therefore, the paper provides a systematic reverse engineering approach that will enhance aircraft conceptual design and flight performance optimization studies.

• 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.

• Journal of Aerospace System Engineering
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• v.4 no.2
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• pp.26-31
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• 2010

Reduction of the aerodynamic drag is one of the most hot issues of car industries. Many researchers have studied in the area of drag reduction methodology using experimental tools or numerical tools. In general, car shape design is the main focus to reduce the drag in aerodynamic research area. However, not many people have studied the aerodynamic interference between running cars to figure out the drag variation. In this research, the aerodynamic interference between two running cars have been analyzed by using numerical tools, FLUENT 6.2. Several different models of cars and two different distances between two running cars are considered.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.373-379
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• 2001

When a train runs into a tunnel at high-speed, aerodynamic drag suddenly increases and the booming noise is generated at the exit of tunnel. The noise shape is very important to reduce the aerodynamic drag in tunnel as well as on open ground, and the micro-pressure wave that is a source of booming noise is dependent on nose shape, especially on area distribution. In this study, the nose shape has been optimized employing the response surface methodology and the axi-symmetric compressible Navier-Stokes equations. The optimal designs have been executed imposing various conditions of the aerodynamic drag and the micro-pressure wave on object functions. The results show that the multi-objective design was successful to decrease micro-pressure wave and aerodynamic drag of trains.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.17-22
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• 2004

A space launch vehicle departs the ground in a low speed, soon reaches a transonic and a supersonic speed, and then flies in a hypersonic speed into the space. Therefore, the design of a launch vehicle should include the prediction of aerodynamic characteristics for all speed regimes, ranging from subsonic to hypersonic speed. Generally, Empirical and analytical methods and wind tunnel tests are used for the prediction of aerodynamic characteristics. This research presents considerable factors for aerodynamic analysis of a launch vehicle using CFD. This investigation was conducted to determine effects of wake over the base section on the aerodynamic characteristics of a launch vehicle and also performed to determine effects of the sting which exist to support wind tunnel test model.