• Journal of Aerospace System Engineering
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• v.12 no.6
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• pp.23-31
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• 2018

In the present work, the thrust and torque of multicopter propellers in hovering are predicted based on BET method. The geometry information of the propellers is obtained using a three dimensional scanner and the airfoil section is extracted using CATIA. EDISON CFD is adopted to calculate the drag and lift of airfoil at a given geometry and flow conditions and then thrust is calculated with respect to a given RPMs based on BET. Two simulations with laminar and turbulent flows are considered. The predicted value is compared with the performance data from the Product Company and results from JavaProp software, which is used in the design and prediction of propellers. In the case of a 9-inch propeller, the thrust from the product company is corresponding to the results between the laminar and turbulent flow conditions. In the 16-inch case, the predicted thrust at turbulent flow conditions conformed well with reference one. The predicted torque shows a big difference with the reference data.

• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.97-100
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• 2012

항력계수와 양력계수는 각각 항력, 양력을 동압과 에어포일의 코드 길이로 나눈 값으로 정의된다. 항공기의 비행에 있어서 항력과 양력은 매우 중요한 요소로 작용하며 항공기의 속도에 따라 항력과 양력은 크게 변하게 된다. 첫째로 학부과정에서 배운 마하수에 따른 항력계수의 변화, 그 중에서도 마하수 1 이상에서의 항력계수 감소에 관한 이론을 살펴보고 EDISON_CFD를 이용하여 마하수에 따른 항력계수의 값을 실제로 측정해보고 비교해보았다. 두 번째로는 EDISON_CFD로 측정한 마하수버에 따른 양력계수 값과 앞서 측정한 항력계수 값을 이용하여 NACA0012의 마하수에 따른 양력과 항력의비 (양항비)를 구하여 실제고도에서 비행 시 NACA0012의 적정 효율을 가지는 마하수를 알아보았다.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.563-568
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• 2015

풍력터변의 성능을 높이기 위한 방법으로 최근 해외에서는 쉬라우드를 장착하여 유입 유량을 증진시키는 형상에 대한 새로운 아이디어가 제안되고 시범적으로 적용되고 있다. 본 연구에서는 쉬라우드가 장착된 수평축 풍력터빈에 대해서 EDISON CFD를 이용하여 쉬라우드 내부로 유입되는 질량 유량의 변동을 몇 가지 형상에 대해 수치적으로 비교 분석하였다. 유동장은 비압축성 난류유동으로 가정하였으며, 수치 해석 결과로부터 쉬라우드 주변의 순환의 세기를 형상 변동에 따라 도출하였다. 쉬라우드 형상으로는 캠버를 갖는 goe 417 에어포일을 두 개의 받음각(5도, 10도)에 대해서 수치해석을 수행하였으며, 브림을 갖는 디퓨저 형상(Wind-lens)에 대해서도 유입 유량 변동과 순환 세기에 대해 수치해석을 수행하고 결과를 상호 비교하였다. 본 연구를 통해 쉬라우드가 발생시키는 순환에 의한 유입 유량 증가 현상을 파악할 수 있었으며, 이로써 풍력터빈의 출력을 증대시킬 수 있음을 확인하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.1
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• pp.1-11
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• 2012

Performance analysis was performed for an autorotating rotor. For a given airspeed, shaft angle, and collective pitch, the steady state of autorotation was judged by using the transient simulation method(TSM), then the thrust, lift, and drag coefficient for that state were computed. Average thrust was calculated from the instantaneous thrusts, in which the TSM was used in blade thrust integration. The analysis method was applied to the model rotor that had been tested by wind tunnel. Some comparison between analysis and test was provided. Two types of two-dimensional airfoil aerodynamic data were utilized in analysis, and they were made by Navier-Stokes Solver in terms of Reynolds and Reynolds-Mach number. The quantitative difference of results using two data set was examined and compared.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.8
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• pp.747-757
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• 2010

The ice accreted on the airfoil is one of the critical drivers that causes the degradation of aerodynamic performance as well as aircraft accidents. Hence, an efficient numerical code to predict the accreted ice shape is crucial for the successful design of de-icing and anti-icing devices. To this end, a numerical code has been developed for the prediction of glaze ice accretion shape on 2D airfoil. Constant Source-Doublet method is used for the purpose of computational efficiency and heat transfer in the icing process is accounted for by Messinger model. The computational results are thoroughly compared against available experiments and other computation codes such as LEWICE and TRAJICE. The direction and thickness of ice horn are shown to yield similar results compared to the experiments and other codes. In addition, the effects of various parameters - temperature, free-stream velocity, liquid water contents, and droplet diameter - on the ice shape are systematically analyzed through parametric studies.

• Journal of Energy Engineering
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• v.29 no.1
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• pp.34-43
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• 2020

A study has been done for self-starting torque of vertical axis wind turbine blade. It is especially concentrated to evaluate the torque coefficient before starting rotation. Two different aerofoils(AMI903 and AMI904) are proposed to benchmark the possible best blade(supercritical airfoil) for self-starting performance. Torque coefficients in the tangential direction of rotation are given with respect to the angle of attack in terms of drag coefficient and lift coefficient. Torque coefficient shows that the effect of Reynolds number is minimal. The thicker blade(AMI904) between two different proposed airfoils has bigger torque coefficient, which is attributed to lower lift coefficient and higher drag coefficient.