• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.6
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• pp.536-541
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• 2012

An instrumented pod has been developed to measure the aeroacoustic environment as well as the conventional data such as load, vibration, and aerodynamic heating of fighters during flight tests, confirming to the recently developed external pod design for fighters. This study presents the development of the measurement system in detail, being the first indigenous effort in its kind. The pod was designed to meet the requirements of the MIL-HDBK-1763 and MIL-STD-810 Method 515, which are the base to determine the locations and range of sensors. The Endevco 8510B-2 was selected as the sensor to withstand the harsh environment during the flight tests. In order to assess the integrity of the fabricated pod design, a ground run-up test of a KF-16 has been conducted with the pod installed at Station 5. The test results show that the system works well but the sound level exceeds the predetermined sensor range. The sensor range has been readjusted for flight test performed later.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.7
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• pp.13-18
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• 2004

This paper describes an efficient and robust optimization method for helicopter rotor airfoil design in forward flight. Navier-Stokes analysis was employed to compute the dynamic response of an airfoil, which simulates the unsteady rotor flow-field in forward flight. The optimization system consists of two categories; Response Surface Method to construct the response surface model based on D-optimal 3-level factorial design, and Genetic Algorithm to obtain the optimum solution of a defined objective function including penalty terms of constraints. The influence of design variables and their interactions on the aerodynamic performance was examined through the optimization process.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.891-898
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• 2007

Optimal aerodynamic design for the pitch-controlled horizontal axis wind turbine and its aerodynamic performance for various pitch angles are performed numerically by using the blade element momentum theory. The numerical calculation includes effects such as Prandtl‘s tip loss, airfoil distribution, and wake rotation. Six different airfoils are distributed along the blade span, and the special airfoil i.e. airfoil of 40% thickness ratio is adopted at the hub side to have structural integrity. The nonlinear chord obtained from the optimal design procedure is linearized to decrease the weight and to increase the productivity with very little change of the aerodynamic performance. From the comparisons of the power, thrust, and torque coefficients with corresponding values of different pitch angles, the aerodynamic performance shows delicate changes for just $3^{\circ}$ increase or decrease of the pitch angle. For precisive pitch control, it requires the pitch control algorithm and its drive mechanism below $3^{\circ}$ increment of pitch angle. The maximum torque is generated when the speed ratio is smaller than the designed one.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.16-26
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• 2005

The aerodynamic design of a proprotor for the Smart UAV adopting tiltrotor aircraft concept is conducted in this study. Since proprotor of tiltrotor aircraft is operated at both rotary and fixed wing mode with single configuration rotor, the proprotor has to be designed to meet performance requirements for both flight modes. The aerodynamic design of proprotor is accomplished by combining three sources of data - the proprotor performance data, the aerodynamic data of vehicle, and the performance data of engine. The performance analysis code for proprotor is based on the combined momentum and blade element theory and validated by comparison with the TRAM data. In order to design configuration for a proprotor satisfying requirements for both rotary and fixed wing mode, various kind of performance maps are constructed for many performance and configuration parameters. From the analysis the twist angle of 38 degrees and the solidity of 0.118 are decided to be the optimal geometric parameters for both operating conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.57-68
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• 2012

In this study, designs of the high efficiency composite propeller blade for a high speed turboprop aircraft, which will be used for a next generation regional commercial aircraft in Korea, are performed. Both the vortex theory and the blade element theory are used for preliminary aerodynamic design and performance analysis of the propeller. Then the aerodynamic design result is confirmed through performance analysis using a commercial CFD code, ANSYS. The carbon/epoxy composite materials is used, and the skin-spar-foam sandwich type structure is adopted for improvement of lightness and structural stability. Finally, it is investigated that the proposed propeller blade has high efficiency and structural safety through both aerodynamic and structural analysis and experimental test of a prototype propeller blade.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.18-27
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• 2006

The conventional reliability based design optimization(RBDO) methods require high computational cost compared with the deterministic design optimization(DO) methods, therefore it is hard to apply directly to large-scaled problems such as an aerodynamic shape design optimization. In this study, to overcome this computational limitation the efficient RBDO procedure with the two-point approximation(TPA) and adjoint sensitivity analysis is proposed, that the computational requirement is nearly the same as DO and the reliability accuracy is good compared with that of RBDO. Using this, the 3-D aerodynamic shape design optimization is performed very efficiently.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.253-258
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• 2012

In this study, designs of the high efficiency composite propeller blade for a high speed turboprop aircraft, which will be used for a next generation regional commercial aircraft in Korea, are performed. Both the vortex theory and the blade element theory are used for preliminary aerodynamic design and performance analysis of the propeller. Then the aerodynamic design result is confirmed through performance analysis using a commercial CFD code, ANSYS. The carbon/epoxy composite materials is used, and the skin-spar-foam sandwich type structure is adopted for improvement of lightness and structural stability. Finally, it is investigated that the proposed propeller blade has high efficiency and structural safety through both aerodynamic and structural analysis and experimental test of a prototype propeller blade.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.12
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• pp.1017-1024
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• 2012

The aerodynamic design and analysis on advanced propeller with blade sweep was performed for recent turboprop aircraft. HS1 airfoil series are selected as a advanced propeller blade airfoil. Adkins method is used for aerodynamic design and performance analysis with respect to the design point. Adkins method is based on the vortex-blade element theory which design the propeller to satisfy the condition for minimum energy loss. Propeller geometry is generated by varying chord length and pitch angle at design point of target aircraft. Advanced propeller is designed by apply the modified chord length, the tip sweep which is based on the geometry of conventional propeller. The aerodynamic characteristics of the designed Advanced propeller were verified by CFD(Computational Fluid Dynamic) and evaluated to be properly designed.

• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.89-92
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• 2012

초음속 항공기를 설계하는데 있어서 일반적인 항공기와는 다른 성능이 요구되는데 그것은 바로 초음속에 의한 충격파가 발생시키는 추가적인 항력을 감소시키는 일이다. 날개의 Airfoil 형상을 결정하기 위해서는 공력 특성을 파악해야 하는데, 이를 알아보는 데 있어서 EDISON_CFD를 사용하였다. 충격파의 생성을 지연시키는 Supercritical Airfoil의 여러 형상에 필요한 격자를 생성하여 비점성, 압축성 유동 해석을 수행하였다. 비교에 필요한 다섯 개의 NASA Supercritical Airfoil을 선정하여, 아음속과 초음속으로 나누어 받음각에 따른 양력계수와 항력계수를 도출하고, 이를 토대로 양항비를 추정해 보았다. 추려진 것 중 가장 우수한 공력성능을 보이는 airfoil을 선정하였는데 그 결과 NASA SC-0403 airfoil의 공력 성능이 가장 뛰어나 그것을 선정하기로 하였고, 또한 2차원 공력 해석에서 얻은 양력계수를 면적에 대하여 적분하여 날개에서의 양력과 항력을 추정하였다.

• Journal of Institute of Convergence Technology
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• v.11 no.1
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• pp.39-42
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• 2021

2차원 유동장내 수직 진동하는 원통의 Von Karman 와열 유동 현상에 대한 진동 주파수 계산 문제는 진동하는 물체의 비정상 공력 해석 연구 검증에 많이 사용하는 고전적 방법이다. 본 연구에서는 오픈소스 OpenFoam 기반의 중첩격자 기법을 사용하여 층류 유동장내의 수직방향 진동하는 원통 주변의 비정상 유동 현상과 원통 벽면에서의 공력 특성 변화를 해석하기 위한 일련의 해석 단계들과 결과를 타 연구그룹과 비교하였다. 원통 형상과 진동에 의한 와열 유동의 주기적 유동 특성과 복잡성 해석의 건전성을 확보하기 위하여 격자와 시간제어에 대한 해의 정확도에 미치는 영향을 평가하였다. 본 연구에서 수행한 해석 방법은 일관성과 신뢰성 있는 해석 결과들 보여주었으며, 향후 보다 실제적인 진동하는 에어 포일의 비정상 공력 해석 연구에 적용 가능함을 확인하였다.