• Title/Summary/Keyword: Aerodynamic Optimization

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Design Optimization of Passive Control Devices for Dynamic Stall Control (동적실속 수동제어장치 최적설계)

  • Joo, Wan-Don;Lee, Bo-Sung;Yee, Kwan-Jung;Lee, Dong-Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.1
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    • pp.11-19
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    • 2005
  • In order to improve dynamic stall characteristics of an oscillating airfoil, optimal design has been performed for fixed nose droop and Gurney flap. Fixed nose droop is known to be very effective to improve pitching moment characteristics but may cause degeneration of aerodynamic lift at the same time. On the other hand, Gurney flap has the opposite characteristics. For fixed nose droop, location and angle are chosen as design variables, while length is defined as design variable for Gurney flap. Higher order response surface methodology and sensitivity based optimal design method are employed to handle highly nonlinear problem such as dynamic stall. Optimal design has been performed so that lift and pitching moment are simultaneously improved. The design results show that aerodynamic characteristics can be remarkably improved through present design approach and the present passive control method is as good as active control method which combines variable nose droop and Gurney flap.

Design Optimization of Transonic Wing/Fuselage System Using Proper Orthogona1 Decomposition (Proper Orthogonal Decomposition을 이용한 천음속 날개/동체 모텔의 최적설계)

  • Park, Kyung-Hyun;Jun, Sang-Ook;Cho, Maeng-Hyo;Lee, Dong-Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.5
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    • pp.414-420
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    • 2010
  • This paper presents a validation of the accuracy of a reduced order model(ROM) and the efficiency of the design optimization using a Proper Orthogonal Decomposition(POD) to transonic wing/fuselage system. Three dimensional Euler equations are solved to extrude snapshot data of the full order aerodynamic analysis, and then a set of POD basis vectors reproducing the behavior of flow around the wing/fuselage system is calculated from these snapshots. In this study, reduced order model constructed through this procedure is applied to several validation cases, and then it is confirmed that the ROM has the capability of the prediction of flow field in the space of interest. Additionally, after the design optimization of the wing/fuselage system with the ROM is performed, results of the ROM are compared with results of the design optimization using response surface model(RSM). From these, it can be confirmed that the design optimization with the ROM is more efficient than RSM.

An External Shape Optimization Study to Maximize the Range of a Guided Missile in Atmospheric Flight (대기권을 비행하는 유도 미사일의 최대 사거리 구현을 위한 외형 형상 최적화 시스템 연구)

  • Yang, Young-Rok;Hu, Sang-Bum;Je, So-Yeong;Park, Chan-Woo;Myong, Rho-Shin;Cho, Tae-Hwan;Hwang, Ui-Chang;Je, Sang-Eon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.6
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    • pp.519-526
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    • 2009
  • This paper describes a research result of a external shape optimization study to maximize the range of the guided missile with canards and tailfins in atmospheric flight. For this purpose, the external shape optimization program which can enhance the range of a missile was developed, incorporated with the trajectory analysis and the optimization technique. In the trajectory analysis part, Missile DATCOM which utilizes the semi-empirical method was directly connected to the trajectory code to supply the aerodynamic coefficients efficiently at every time step. In the gliding flight trajectory after apogee, a maximum $C_L/C_D$ trim condition calculation module was attached under the assumption of the missile continuously flying at maximum $C_L/C_D$ condition. In the optimization part, a Response Surface Method(RSM) was adopted to reduce the computing time.

Optimal Design of Impeller Shroud for Centrifugal Compressor Using Response Surface Method (반응표면법을 이용한 원심압축기 임펠러 쉬라우드 형상최적설계)

  • Kang, Hyun-Su;Hwang, In-Ju;Kim, Youn-Jea
    • The KSFM Journal of Fluid Machinery
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    • v.18 no.4
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    • pp.43-48
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    • 2015
  • In this study, a method for optimal design of impeller shroud for centrifugal compressor using response surface method (RSM) and multi-objective genetic algorithm (MOGA) was studied. Numerical simulation was conducted using ANSYS CFX with various configurations of shroud. Each of the design parameters was divided into 3 levels. Total 15 design points were planned by central composite design (CCD) method, which is one of the design of experiment (DOE) techniques. Response surfaces based on the results of DOE were used to find the optimal shape of impeller shroud for high aerodynamic performance. The whole process of optimization was conducted using ANSYS Design Xplorer (DX). Results showed that the isentropic efficiency, which is the main performance parameter of the centrifugal compressor, was increased 0.4% through the optimization.

A Study on Numerical Optimization Method for Aerodynamic Design (공력설계를 위한 수치최적설계기법의 연구)

  • Jin, Xue-Song;Choi, Jae-Ho;Kim, Kwang-Yong
    • The KSFM Journal of Fluid Machinery
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    • v.2 no.1 s.2
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    • pp.29-34
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    • 1999
  • To develop the efficient numerical optimization method for the design of an airfoil, an evaluation of various methods coupled with two-dimensional Naviev-Stokes analysis is presented. Simplex method and Hook-Jeeves method we used as direct search methods, and steepest descent method, conjugate gradient method and DFP method are used as indirect search methods and are tested to determine the search direction. To determine the moving distance, the golden section method and cubic interpolation method are tested. The finite volume method is used to discretize two-dimensional Navier-Stokes equations, and SIMPLEC algorithm is used for a velocity-pressure correction method. For the optimal design of two-dimensional airfoil, maximum thickness, maximum ordinate of camber line and chordwise position of maximum ordinate are chosen as design variables, and the ratio of drag coefficient to lift coefficient is selected as an objective function. From the results, it is found that conjugate gradient method and cubic interpolation method are the most efficient for the determination of search direction and the moving distance, respectively.

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Shape optimization of corner recessed square tall building employing surrogate modelling

  • Arghyadip Das;Rajdip Paul;Sujit Kumar Dalui
    • Wind and Structures
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    • v.36 no.2
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    • pp.105-120
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    • 2023
  • The present study is performed to find the effect of corner recession on a square plan-shaped tall building. A series of numerical simulations have been carried out to find the two orthogonal wind force coefficients on various model configurations using Computational Fluid Dynamics (CFD). Numerical analyses are performed by using ANSYS-CFX (k-ℇ turbulence model) considering the length scale of 1:300. The study is performed for 0° to 360° wind angle of attack. The CFD data thus generated is utilised to fit parametric equations to predict alongwind and crosswind force coefficients, Cfx and Cfy. The precision of the parametric equations is validated by employing a wind tunnel study for the 40% corner recession model, and an excellent match is observed. Upon satisfactory validation, the parametric equations are further used to carry out multiobjective optimization considering two orthogonal force coefficients. Pareto optimal design results are presented to propose suitable percentages of corner recession for the study building. The optimization is based on reducing the alongwind and crosswind forces simultaneously to enhance the aerodynamic performance of the building.

Flying-Wing Type UAV Design Optimization for Flight Stability Enhancement (전익기형 무인기의 비행 안정성 향상을 위한 형상 최적화 연구)

  • Seong, Dong-gyu;Juliawan, Nadhie;Tyan, Maxim;Kim, Sanho;Lee, Jae-woo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.10
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    • pp.809-819
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    • 2020
  • In this study, the twist angle and wing planform shapes were selected as design variables and optimized to secure the stability of the flying-wing type UAV. Flying-wing aircraft has no separated fuselage and tails, which has advantages in aerodynamic characteristics and stealth performance, but it is difficult to secure the flight stability. In this paper, the sweep back angle and twist angle were optimized to obtain the lateral stability, the static margin and wing planform shapes were optimized to improve the longitudinal stability of the flying-wing, then effect of the twist angle was confirmed by comparing the stability of the shape with the winglet and the shape with the twist angle. In the optimization formulation, focusing on improving stability, constraints were established, objective functions and design variables were set, then design variable sensitivity analysis was performed using the Sobol method. AVL was used for aerodynamic analysis and stability analysis, and SQP was used for optimization. The CFD analysis of the optimized shape and the simulation of the dynamic stability proved that the twist angle can be applied to the improvement of the lateral stability as well as the stealth performance in the flying-wing instead of the winglet.

A Study on Real-Coded Adaptive Range Multi-Objective Genetic Algorithm for Airfoil Shape Design (익형 형상 설계를 위한 실수기반 적응영역 다목적 유전자 알고리즘 연구)

  • Jung, Sung-Ki;Kim, Ji-Hong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.7
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    • pp.509-515
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    • 2013
  • In this study, the real-coded adaptive range multi-objective genetic algorithm code, which represents the global multi-objective optimization algorithm, was developed for an airfoil shape design. In order to achieve the better aerodynamic characteristics than reference airfoil at landing and cruise conditions, maximum lift coefficient and lift-to-drag ratio were chosen as object functions. Futhermore, the PARSEC method reflecting geometrical properties of airfoil was adopted to generate airfoil shapes. Finally, two airfoils, which show better aerodynamic characteristics than a reference airfoil, were chosen. As a result, maximum lift coefficient and lift-to-drag ratio were increased of 4.89% and 5.38% for first candidate airfoil and 7.13% and 4.33% for second candidate airfoil.

Dynamic Stall Control Using Aerodynamic Sensitivity Analysis (민감도 해석을 이용한 동적실속 제어)

  • Ahn, Tai-Sul;Kim, Hyoung-Jin;Kim, Chong-Am;Rho, Oh-Hyun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.8
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    • pp.10-20
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    • 2002
  • The present paper investigates methods to control dynamic stall using an optimal approach. An unsteady aerodynamic sensitivity analysis code is developed by a direct differentiation method from a two-dimensional unsteady compressible Navier-Stokes solver including a two-equation turbulence model. Dynamic stall control is conducted by minimizing an objective function defined at an instant instead of integrating for a period of time. Unsteady sensitivity derivatives of the objective function are calculated by the sensitivity code, and optimization is carried out using a linear line search method at every physical time step. Numerous examples of dynamic stall control using control parameters such as nose radius, maximum thickness of airfoil, or suction show satisfactory results.

System Identification and Stability Evaluation of an Unmanned Aerial Vehicle From Automated Flight Tests

  • Jinyoung Suk;Lee, Younsaeng;Kim, Seungjoo;Hueonjoon Koo;Kim, Jongseong
    • Journal of Mechanical Science and Technology
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    • v.17 no.5
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    • pp.654-667
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    • 2003
  • This paper presents a consequence of the systematic approach to identify the aerodynamic parameters of an unmanned aerial vehicle (UAV) equipped with the automatic flight control system. A 3-2-1-1 excitation is applied for the longitudinal mode while a multi-step input is applied for lateral/directional excitation. Optimal time step for excitation is sought to provide the broad input bandwidth. A fully automated programmed flight test method provides high-quality flight data for system identification using the flight control computer with longitudinal and lateral/directional autopilots, which enable the separation of each motion during the flight test. The accuracy of the longitudinal system identification is improved by an additional use of the closed-loop flight test data. A constrained optimization scheme is applied to estimate the aerodynamic coefficients that best describe the time response of the vehicle. An appropriate weighting function is introduced to balance the flight modes. As a result, concurrent system models are obtained for a wide envelope of both longitudinal and lateral/directional flight maneuvers while maintaining the physical meanings of each parameter.