• 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.44 no.10
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• pp.877-886
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• 2016

A validation study is conducted for the conceptual design and performance analysis of UH-60A Black Hawk in order to establish the conceptual design and performance analysis techniques for conventional helicopters using a single main rotor and a tail rotor. As a tool for conceptual design and analysis, NDARC(NASA Design and Analysis of Rotorcraft) is used for the present study. The conceptual design for UH-60A is successfully validated as compared with the target values. Then, various performance analyses in hover and forward flight are conducted for the UH-60A model obtained from the present design work, and they are compared well with the wind tunnel test, flight test, and previous analyses using various analysis tools. Through this validation work, the conceptual design and performance analysis techniques for the conventional helicopter are appropriately established.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.351-357
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• 2017

차량용 브레이크의 성능은 브레이크 디스크 로터의 냉각 성능과 밀접한 관련이 있다. 냉각 성능 향상을 위해 디스크 로터에 구멍을 뚫거나 홈을 깎아내어 열 전달면을 극대화 시키거나 열 전도도가 높은 재료에 대한 연구가 활발하게 진행되고 있다. 본 연구에서는 각각 형상이 다른 디스크 브레이크 시스템의 방열 및 제동 성능, 패드 압력에 대한 응력을 분석하고 온도장 근사 및 열전도 해석 프로그램(Heat_transfer, KAIST, EDISON)과 Elastic-Plastic Analysis SW(CSD_EPLAST, 서울과학기술대학교, EDISON) 및 ABAQUS를 이용해 각각의 냉각 성능 및 응력 분포를 비교 분석한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.86-90
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• 1992

스크류 압축기는 진동이 작고 맥동이 적으며, 소형이고 고효율이라는 특징이 있다. 또한 식품, 화학, 전자공업 등에서 무윤활식 압축기로 사용되어지고 있다. 본 연구에서는 호프로 자른 것과 같은 다각형 오차를 만들지 않고 매끄러운 면을 얻을 수 있는 스크류 로터의 축직각 단면좌표를 이용한 cutter의 형상을 설계하는 것을 목적으로 한다.

• Aerospace Engineering and Technology
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• v.11 no.1
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• pp.19-26
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• 2012

The requirement for the aerodynamic hub drag, allocated from the system requirement of development of a bearingless rotor hub, was analyzed and embodied to be substantiated by the methodology assigned from the requirement. Drag prediction for the initial hub configuration was carried out by hand calculation using aerodynamic drag coefficients and the design change about the sectional shape of torque tube was suggested to satisfy the requirement. Finally, drag prediction was performed for the changed hub configuration by using unstructured overset mesh technique and parallel computation and the calculated result satisfied the requirement of the aerodynamic hub drag. It was found that the drag of final hub configuration was also within the range of drag inferred from the trendline of developed helicopter.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1038-1044
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• 2017

We are working on improving the performance by applying the three-dimensional design element to the rotor blades of high pressure supersonic impulse turbine that drives turbo pump of liquid rocket engine. In this paper, based on the shape of a rotor blade of a turbopump turbine designed in the past, a three-dimensional shape is applied to a rotor blade through a stacking line change such as sweep and dihedral. After performing the flow analysis, the changes in the turbine performance characteristics for each design element were carefully examined and the results were summarized.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.331-336
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• 2006

This paper studies the effects of the nozzle-rotor axial clearance of a supersonic turbine on turbine performance. The nozzle-rotor axial clearance of the supersonic turbine developed to drive a turbopump for 30 ton class liquid rocket engines was varied and a numerical analysis of the turbines having the different nozzle-rotor axial clearances was conducted. It has been found that turbine performance degrades with an increasing axial clearance due to the increased stagnation pressure loss in the axial clearance region.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.1-9
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• 2014

The present study was conducted by using fast-responding PSP technique to measure the surface pressure on a small-scale rotor blade in hover. Also, the study was performed to verify the accuracy and investigate its possibility of PSP application for rotor blade pressure measurement. Pulsed laser which has 532 nm wavelength was used as a light source. Lifetime measurement technique was applied. Also, the coated paint on a rotor blade was porous PSP which has faster response time than conventional PSP. The blades had NACA0012 airfoils. The length of rotor blade was 340 mm and chord was 40 mm with rectangular shape 1 set, and 4 sets had several tip sweepback angles. The measured results qualitatively showed that the upper surface pressure decreases with increasing the collective pitch angle. Quantitative pressure coefficients of PSP results were higher approximately 0.4 to 0.7 than the pressure tap data of the NASA experiment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.6
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• pp.429-439
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• 2013

The purpose of current study is to develop the rotor analysis solver and perform a rotor aerodynamic analysis in the wind fence. To this end, the rotor analysis solver based on actuator disk model was employed. To consider the asymmetric effect of the rotor in the wind fence, the flapping motion analysis was conducted with blade element theory for the effective angle of attack calculation. The validation cases which are the rotor with wall and ground were accomplished by developed solver. The decrease of rotor performance by wind fence was confirmed. The wind fence configuration was suggested which guarantees more than 95% rotor performance compared with the no fence case.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.513-520
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• 2014

An unmanned aerial vehicle (UAV) should be designed to be as small and lightweight as possible to optimize the efficiency of changing the blade shape to enhance the aerodynamic performance, such as the thrust and power. In this study, a computational fluid dynamics (CFD) simulation of an unmanned multi-rotor aerial vehicle in hover mode was performed to explore the thrust performance in terms of the blade rotational speed and blade shape parameters (i.e., taper ratio and twist angle). The commercial ADINA-CFD program was used to generate the CFD data, and the results were compared with those obtained from blade element theory (BET). The results showed that changes in the blade shape clearly affect the aerodynamic thrust of a UAV rotor blade.