• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.51-56
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• 2009

Optimization with metamodel is one of numerical optimization methods. Response surface method is performed for making metamodel. The Hcks-Henne function is used for designing 2D shape of the airfoil and spring analogy is used to change the grid according to the change in shape of the airfoil. Aerodynamic coefficient required for response surface method are obtained by using Navier-Stokes solver with $\kappa-\omega$ shear stress transport turbulence model. For the baseline airfoils, OA 312, OA 309, and OA 407 airfoils select and optimize to improve aerodynamic performance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.8
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• pp.957-968
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• 1999

Performance tests of an airfoil fan and measurement of flow fields at the impeller exit are carried out to investigate the effects of the tip clearance between the rotor and inlet casing on the impeller performance. The impeller is twelve bladed of NACA 65-810 airfoils and tested with 3 different size of gap; 1, 2, 4mm. The relative decrease of pressure rising performance of the fan is 15 percent for the design flow rate when the gap size is 1 percent of the impeller diameter. The reduction of performance becomes large as the flow rate increases. The leakage flow through the clearance affects the through flow of the impeller, which results in decrease of the slip factor as well as the impeller efficiency. The data base obtained in the present study can be used for the design and flow analysis of the airfoil fans.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.4
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• pp.273-284
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• 2012

In this paper, a study on the design of high speed airfoil is described. Various airfoils are investigated and existing airfoils are geometrically interpolated to generate new airfoils. An optimization method is applied to theses new airfoils and their aerodynamic performances are optimized. Through this study, it is demonstrated that the airfoil can be designed using the geometrical interpolation and the optimization method to exhibit good aerodynamic performances.

• IE interfaces
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• v.13 no.4
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• pp.703-708
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• 2000

In manufacturing processes, manufacturing features always deviate somewhat from their nominal design specifications due to several types of errors. This study suggests a fitting algorithm of the geometric profile parameters of leading and trailing edges for turbine compressor airfoils. In reality, industry personnels inspect the airfoil profile by trial-and-error method to determine the geometric feature parameters. In this study we propose an exploration approach based on factorial design with center point to minimize the effect of measurement errors caused by probe slip. By adopting the fitting method developed in this paper, one can enhance the precision and efficiency of fitting the airfoil edge profile.

• Journal of applied mathematics & informatics
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• v.4 no.1
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• pp.167-178
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• 1997

In this paper we present an application to airfoil design of an optimum design method based on optimal control theory. The method used here transforms the design problem by way of a change of variable into an optimal control problem for a distributed system with Neumann boundary control. This results in a set of variational inequalities which is solved by adding a penalty term to the differential equation. This si inturn solved by a finite element method.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.3
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• pp.317-322
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• 2012

The low speed aerodynamic characteristics for a modified sonic arc airfoil which is designed by using the nose shape function of sonic arc, the shape function of NACA four-digit wing sections, and Maple are experimentally investigated. The small rotor blades of a modified sonic arc and NACA0012 airfoil are precisely fabricated with a commercially available light aluminum(Al 6061-T6) and are spin tested over a low speed range (3000rpm-5000rpm). In a consuming power comparison, the consuming powers of NACA0012 are higher than that of modified sonic arcs at each pitch angle. The measured rotor thrust for each pitch angle is used to estimate the rotor thrust coefficient according to momentum theory in the hover state. The value of thrust coefficients for both two airfoils at each pitch angle show almost constant values over the low Mach number range. However, the rotor thrust coefficient of NACA0012 is higher than that of the modified sonic arc at each pitch angle. In conclusion, the aerodynamic performance of NACA0012 is better than that of modified sonic arcs in the low speed regime. This test model will provide a convenient platform for improving the aerodynamic performance of small scale airfoils and for performing design optimization studies.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.1014-1019
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• 2001

A numerical investigation was performed to determine the effect of airfoil on the optimum flap height using NACA 00XX and 44XX airfoils. The six flaps which have 0.5% chord height difference were selected. A Navier-Stokes code, FLUENT, was used to calculate the flow field of the airfoil. The code was first tested as a benchmark by modelling flow around a NACA 4412 airfoil. Predictions of local pressure coefficients are found to be in good agreement with the result of the experimental result. For every NACA 00XX and 44XX airfoil, flap heights ranging from 0.0% to 2.5% chord were changed by 0.5% chord interval and their effects were also studied. Representative results from each case are presented graphically and discussed. It is concluded that this initial approach gives an idea for the future development of the wind turbine optimum design.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.377-380
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• 2008

In this study, an aerodynamic shape optimization system was developed to study the optimal shape of airfoil. The system consists of GA (Genetic Algorithm) and CFD code based on the Navier-Stokes equation. Lift-drag ratio is chosen as the object function and optimization is conducted for PARSEC airfoil with nine design variables, which is very efficient in representing the surface geometry of airfoil.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.4
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• pp.17-23
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• 2002

The present paper describes the optimum inverse design of 2-D linear cascade airfoil. The pressure coefficient of an airfoil surface is taken as the objective function, and non-orthogonal incompressible Navier-Stokes equation is applied to calculate the pressure coefficient. Both of steepest descent and conjugate gradient method have been used to make the objective function go to zero. The 1st order finite differential method is applied to the searching direction and the golden section method is used to compute the searching distance. As a result of the present work, a good convergence to the target airfoil has been obtained.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.7
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• pp.2347-2355
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• 1996

Purpose of the present study is to develop a computational design program for shape optimization, combining the numerical optimization technique with the flow analysis code. The present methodology is then validated in three cases of aerodynamic shape optimization. In the numerical optimization, a feasible direction optimization algorithm and shape functions are considered. In the flow analysis, the Navier-Stokes equations are discretized by a cell-centered finite volume method, and Roe's flux difference splitting TVD scheme and ADI method are used. The developed design code is applied to a transonic channel flow over a bump, and an external flow over a NACA0012 airfoil to minimize the wave drag induced by shock waves. Also a separated subsonic flow over a NACA0024 airfoil is considered to determine a maximum allowable thickness of the airfoil without separation.