• 한국전산유체공학회지
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• 제20권1호
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• pp.47-56
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• 2015

In this paper, we study the effect of various turbulence models by comparing the aerodynamic characteristics and the flow patterns computed for aircraft models. An in-house CFD solver, MSAPv, that solves the three dimensional RANS equations with the turbulence model equations is used. The turbulence models used in this study are the Spalart-Allmaras model, Menter's $k-{\omega}$ SST model, Coakley's $q-{\omega}$ model, and Huang and Coakley's $k-{\varepsilon}$ model. DLR-F6 WB and WBNP configurations are selected for the study. We concentrate on the separated flow pattern variations with the turbulence models at the wing-body junction and the wing-pylon junction as well as drag polar curves.

• 한국항공운항학회:학술대회논문집
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• 한국항공운항학회 2007년도 추계학술대회
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• pp.18-20
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• 2007

• 한국항공운항학회지
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• 제31권3호
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• pp.30-41
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• 2023

Aviation turbulence, caused by atmospheric eddies, is a disruptive phenomenon that leads to abrupt aircraft movements during flight. To minimize the damages caused by such aviation turbulence, the Aviation Meteorological Office provides turbulence information through the Korea aviation Turbulence Guidance (KTG) and the Global-Korean aviation Turbulence Guidance (GKTG). In this study, we evaluated the performance of the KTG and GKTG models by comparing the in-situ EDR observation data and the generated aviation turbulence prediction data collected from the mid-level Korean Peninsula region from January 2019 to December 2021. Through objective validation, we confirmed the level of prediction performance and proposed improvement measures based on it. As a result of the improvements, the KTG model showed minimal difference in performance before and after the changes, while the GKTG model exhibited an increase of TSS after the improvements.

• 항공우주시스템공학회지
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• 제9권4호
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• pp.62-66
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• 2015

During the conceptual design of turboprop aircraft, the power effect driven from rotating propeller is typically obtained from empirical data. In the present paper, propeller power effect was obtained by using unsteady three-dimensional Navier-Stokes solver with $k-{\omega}$ turbulence model for the accurate prediction of turboprop aircraft performance. In order to simulate the relative motion between propeller and fuselage, unsteady sliding mesh method was used. During simulation, three flow conditions such as climb, cruise and descending flight were selected considering the flight envelop of the real turboprop aircraft. For the correction of aerodynamic coefficients, the thrust effect of engine exhaust gas was included based on the engine manufacturer's data. Using the computational results, the correction table for the aerodynamic coefficient of turboprop aircraft was suggested for the performance analysis of turboprop aircraft.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1659-1662
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• 1997

The objective of this paper is to estimate the aerodynamic derivatives of a single turbo-prop aircraft at a specified flight condition for the best deduction of the dynamic characteristics using modified maximum likelihood estimation method whcih is known to be unbiased, efficient, and consistent. The flight test data necessary to the estimation of aerodynamic derivatives is obtained by implementing the six degree of freedom nonlinear flight simulation to consider the effects of several control input types, control deflection amplitudes, and intensity of turbulence. The simulated data is added with the measurement noise, which is regarded as the actual flight test data.

• 제어로봇시스템학회논문지
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• 제4권1호
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• pp.38-44
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• 1998

The modified maximum likelihood estimation method is used to estimate the nondimensional aerodynamic derivatives of a single turbo-prop aircraft at a specified flight condition for the best deduction of the dynamic characteristics. In wind axes the six degree of freedom equations are algebraically linearized so that the linear state equation contains aerodynamic derivatives in a state-space form and is used in the maximum likelihood method. The simulated data added with the measurement noise is used as a flight test data which is necessary to the estimation of nondimensional aerodynamic derivatives. It is obtained by implementing the 6-DOF nonlinear flight simulation. In the flight simulation, the effects of several control input types, control deflection amplitudes, and the turbulence intensities on the statistical convergence criteria are also examined and quantitative analysis of the results is discussed.

• 한국항공운항학회지
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• 제21권4호
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• pp.1-10
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• 2013

This paper addresses the derivation of 6-DOF equation of Tanker and Receiver's aircraft for aerial refueling. The new set of nonlinear equations are derived in terms of the relative translational and rotational motion of receiver aircraft respect to the tanker aircraft body frame. Further the wind effect terms due to the tanker's turbulence are included. The derivation of absolute dynamic equation for tanker aircraft written in the inertial frame is calculated from the relative dynamics equations of receiver. The derived relative and absolute equations are implemented the simulation in the same flight conditions to verify the relative motion and compare the trim results by using the MATLAB/SIMULINK program.

• Advances in aircraft and spacecraft science
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• 제8권4호
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• pp.303-330
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• 2021

The paper discusses the effect of the winglets on the aerodynamic and aeroacoustic performance of Boeing 737-800 aircraft by numerical approach. For this purpose, computational fluid dynamics and fluent commercial software are used to solve the compressible flow governing equations. The RANS method and the K-ω SST turbulence model are selected to simulate the subsonic flow around the wing with acceptable accuracy and low computational cost. The main variables of steady flow around the simple and blended wing in constant atmospheric conditions are computed by numerical solution of governing equations. The solution of the acoustic field has also been accomplished by the broad-band acoustic source model. The results reveal that adding a blended winglet increases the pressure difference near the wingtip,which increases the lift force. Also, the blended winglet reduces the power and magnitude of vorticities around the wingtip, which reduces the wing's drag force. The effects of winglets on aerodynamic forces lead to a 3.8% increase in flight range and a 3.6% increase in the maximum payload of the aircraft. Also, the acoustic power level variables on the surfaces and fields around the wing have been investigated integrally and locally.

• 대한전자공학회논문지TE
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• 제39권4호
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• pp.350-354
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• 2002

본 논문에서는 무인비행체를 특정 위치로 유도하기 위한 자동조종장치를 설계하였으며, 설계되어진 자동 조종장치에 대해 외부 교란에 대한 강건성을 시험하였다. 무인비행체의 속도를 저속, 순항, 고속으로 분류하여 각각의 속도에 대한 자동조종장치를 설계하였으며, 설계되어진 자동조종장치의 이득에 대해 이득 스케듈링을 수행하였다. 무인비행체의 운용고도에 따라 대기교란 모델을 발생하였고, 모의실험을 통해 이에 따른 무인비행체 자동조종장치의 강건성을 증명하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.757-761
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• 2008

The aerostat dynamic equation of motion has been built including the tether cable dynamic effects. A numerical program to solve the derived equation of motion has been developed. The dynamic motion of the 32m aerostat has been analyzed under discrete gust and continuous turbulence. The aerostat behaviors under discrete gust which represents a deterministic approach for determining design loads for manned aircraft are solved to verify the effect of aerostat mechanical properties on the aerostat dynamic behavior. Continuous turbulences are simulated for each given altitude, translational mean wind velocity and gust intensity. Dynamic behaviors of the 32m aerostat are simulated for each continuous turbulence conditions. Translational and vertical velocity and pitching behavior and tether reaction force are monitored for each simulation.