• Wind and Structures
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• 제32권3호
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• pp.205-217
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• 2021

Cold regions with high air density and wind speed attract wind energy producers across the globe exhibiting its potential for wind exploitation. However, exposure of wind turbine blades to such cold conditions bring about devastating impacts like aerodynamic degradation, production loss and blade failures etc. A series of wind tunnel tests were performed to investigate the effect of icing on the aerodynamic properties of wind turbine blades. A baseline clean wing configuration along with four different ice accretion geometries were considered in this study. Aerodynamic force coefficients were obtained from the surface pressure measurements made over the test model using MPS4264 Simultaneous pressure scanner. 3D printed Ice templates featuring different ice geometries based on Icing Research Tunnel data is utilized. Aerodynamic characteristics of both the clean wing configuration and Ice accreted geometries were analysed over a wide range of angles of attack (α) ranging from 0° to 24° with an increment of 3° for three different Reynolds number in the order of 105. Results show a decrease in aerodynamic characteristics of the iced aerofoil when compared against the baseline clean wing configuration. The key flow field features such as point of separation, reattachment and formation of Laminar Separation Bubble (LSB) for different icing geometries and its influence on the aerodynamic characteristics are addressed. Additionally, attempts were made to understand the influence of Reynolds number on the iced-aerofoil aerodynamics.

• Journal of Advanced Marine Engineering and Technology
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• 제17권1호
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• pp.33-44
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• 1993

Active control of a flow field is essential to design efficient parts or elements relating to fluid machineries. The present study is aimed to suggest a new discretization technique of the convection term by renewing the non-conservative equation found in SOLA-VOF into a conservative one. And, as an application, flow characteristics are investigated by adjusting the backward ejecting velocity of 2-D square prism to control the aerodynamic properties. Strouhal number, drag and lift coefficient are compared in terms of various ejecting velocity. Among the results, the transient weak fluctuation of the lift and drag coefficient when the ejecting velocity equals channel inlet velocity is remarkably noticed.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.492-492
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• 2009

Nowadays in Republic of Korea, there is no distinct reference for the related design technology of rotor blade of wind turbine. Therefore the optimum design and evaluation of performance is carried out with foreign commercial code softwares. This paper shows in-house code software that evaluates the aerodynamic design of wind turbine rotor blade using blade element-momentum theory (BEMT) and processes that is applied through various aerodynamics theories such as momentum theory, blade element theory, prandtl's tip loss theory and strip theory. This paper presents the results of the numerical analysis such as distribution of aerodynamic properties and performance curves using in-house code POSEIDON.

• Advances in aircraft and spacecraft science
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• 제8권4호
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• pp.331-344
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• 2021

Airframe internal and external specifications are the product of intensive intellectual efforts and technological breakthroughs distinguishing each aircraft manufacturer. Therefore, geometrical information characterizing aircraft primary aerodynamic surfaces remain classified. When attempting to model real aircraft, many members of the aeronautical community depend on their personal expertise and generic design principles to bypass the confidentiality obstacles and sketch real aircraft airfoils, which therefore vary for the same aircraft due to the different designers' initial assumptions. This paper presents a photogrammetric shape prediction method for deriving geometrical properties of real aircraft airframe by utilizing their publicly accessible static and dynamic visual content. The method is based on extracting the visually distinguishable curves at the fairing regions between aerodynamic surfaces and fuselage. Two case studies on B-29 and B-737 are presented showing how to approximate the sectional coordinates of their wing inboard airfoils and proving the good agreement between the geometrical and aerodynamic properties of the replicated airfoils to their original versions. Therefore, the paper provides a systematic reverse engineering approach that will enhance aircraft conceptual design and flight performance optimization studies.

• 대한토목학회논문집
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• 제30권3A호
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• pp.241-256
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• 2010

본 연구에서는 변장비 70에 가까운 도전적인 현수교 단면을 개발하는데 목적을 두고 있다. 이를 위하여 먼저 강박스 현수교의 제원을 수집 분석하였다. 그 결과를 보면 강박스 현수교에서 경간장과 형상변수(교폭, 형고, 변장비, 고폭비)는 상관관계가 낮았고 고유진동수와 형상변수의 상관관계도 낮은 것으로 나타났으며, 상관관계가 높은 경간장과 고유진동수 관계는 신뢰구간별 추정식을 제시하였다. 그리고 교폭, 진동수비, 질량, 질량관성모멘트, 수직 및 비틈 고유진동수 변화에 따른 플러터 풍속의 민감도 분석을 실시하였는데, 타 변수보다 비틈 고유진동수가 플러터 풍속에 미치는 영향이 가장 큰 것으로 나타났다. 주경간장 1111 m인 현수교의 내풍 단면을 개발하기 위하여 최소 단면폭과 형고를 제약조건으로 하여 총 30개의 단면에 대한 풍동실험을 실시하고, 이로부터 한계풍속 기준을 충분히 만족하는 단면을 찾았다. 그리고 다중모드 플러터 해석으로 개발한 단면의 내풍안정성을 검증하였다. 본 연구에서 제시한 세장 단면은 향후 장대 현수교 설계시 활용할 수 있을 것으로 판단된다.

• 대한토목학회논문집
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• 제31권5A호
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• pp.341-349
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• 2011

본 연구에서는 다양한 풍동실험을 통하여 기류 조건에 따른 트윈박스 거더 교량의 공기역학적 특성을 파악하는데 그 목적이 있다. 이를 위하여 자연적인 난류를 생성할 수 있는 능동 난류 발생장치를 개발하였고 검증하였다. 그리고 능동 난류 및 격자 난류 조건하에서 정적공기력, 비정상공기력 그리고 버페팅 응답 측정 실험을 수행하였다. 풍동실험 결과를 보면, 난류 적분길이는 교량의 정적공기력과 $A_1^*$를 제외한 플러터계수에는 영향을 주지 않는 것으로 나타났다. 그리고 난류 강도는 비정상공기력에 일부 영향을 미치고, 난류 적분길이 또한 일부 수직 방향 성분에 영향을 주는 것으로 나타났다.

• 한국태양에너지학회 논문집
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• 제33권1호
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• pp.40-47
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• 2013

An aerodynamic design tool was developed for small wind turbine blades based on the blade element momentum theory. The lift and drag coefficients of blades that are needed for aerodynamic blade design were obtained in real time from the Xfoil program developed at University of Illinois. While running, the developed tool automatically accesses the Xfoil program, runs it with proper aerodynamic and airfoil properties, and finally obtains lift and drag coefficients. The obtained aerodynamic coefficients are then used to find out optimal twist angles and chord lengths of the airfoils. The developed tool was used to design a wind turbine blade using low Reynolds number airfoils, SG6040 and SG6043 to have its maximum power coefficient at a specified tip speed ratio. The performance of the blade was verified by a commercial code well known for its prediction accuracies.

• 한국가시화정보학회지
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• 제21권2호
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• pp.83-90
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• 2023

The shape of an airfoil is a critical factor in determining aerodynamic characteristics such as lift and drag. Aerodynamic properties of an airfoil have a decisive impact on the performance of various engineering applications, including airplane wings and wind turbine blades. Therefore, it is essential to analyze the aerodynamic characteristics of airfoils. Various analytical tools such as experiments, computational fluid dynamics, and Xfoil are used to perform these analyses, but each tool has its limitation. In this study, airfoil parameterization, image recognition, and artificial intelligence are combined to overcome these limitations. Image and coordinate data are collected from the UIUC airfoil database. Airfoil parameterization is performed by recognizing images from image data to build a database for deep learning. Trained model can predict the aerodynamic characteristics not only of airfoil images but also of sketches. The mean absolute error of untrained data is 0.0091.

• 한국공간구조학회논문집
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• 제14권4호
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• pp.47-54
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• 2014

This paper presents the structural model development and verification processes of wind turbine blade. The National Renewable Energy Laboratory (NREL) Phase VI wind turbine which the wind tunnel and structural test data has publicly available is used for the study. The wind turbine assembled by blades, rotor, nacelle and tower. The wind blade connected to rotor. To make the whole turbine structural model, the mass and stiffness properties of all parts should be clear and given. However the wind blade, hub, nacelle, rotor and power generating machinery parts have difficulties to define the material properties because of the composite and assembling nature of that. Nowadays to increase the power generating coefficient and cost efficiency, the highly accurate aerodynamic loading evaluating technique should be developed. The Fluid-Structure Interaction (FSI) is the emerging new way to evaluate the aerodynamic force on the rotating wind blade. To perform the FSI analysis, the fluid and structural model which are sharing the associated interface topology have to be provided. In this paper, the structural model of blade development and verifying processes have been explained for Part1. In following Part2 paper, the processes of whole turbine system will be discussing.

• 제어로봇시스템학회논문지
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• 제8권8호
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• pp.633-638
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• 2002

We study how the missile autopilot with three loop acceleration structure is related to the aerodynamic characteristics. First, the relationships between the response characteristics of wingless-tail controlled missile and aerodynamics are derived. Next the maximum allowable performance limit of autopilot and the design direction for a missile shape are indicated using the property of zero. The method proposed in this paper may give a help to the missile autopilot system design and determination of the shape of aerodynamic. Also, the validity of proposed method is demonstrated via numerical example.