상용 유동해석 프로그램 ANSYS CFX를

활용한 풍력터빈 블레이드 성능해석

㈜ 디엔디이 / 최낙준

2010. 04

순서

Wind Turbine Blade Design & Modeling

CFD Analysis Pre-processor

CFD Analysis Post-processor

CFD Analysis FSI

CFD Analysis FSI Results

Purpose

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Sources of electricity in the next 50 years

Source: Shell Energy Scenarios to 2050, Shell International Ltd, London , 2007.

• Energy demand will increase dramatically in the next 50 years

• Forecast and historic data show a steep increase in the renewable energy

portion of total electricity production.

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Detailed forecast of electricity production in the next 50 years

Surprise

Geothermal

Solar

New Biomass

Wind

NuclearHydro

Gas

Oil & NGL

CoalTraditional Biomass

Today

Exa-Jo

ule

s

Source: The Evolution of the World’s Energy Systems, Shell International Ltd, London, 1995.

• Wind power is one of the main sources of renewable energy

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New Needs

• Growth in the wind power market combined with the liberalization of energy

markets mean:

– Increase in competition

– Fewer “low-hanging fruit” opportunities

• New wind power projects will need to be more competitive to guarantee a ROI:

– More accurate estimate of energy production potential for sites and installation types

– Improved predictability: higher market value of produced energy, reduced fines

– More stringent engineering margins

• The increased demands on the design and analysis of wind power projects can be

addressed by the use of engineering simulations.

– Proven techniques used widely in other high-tech areas: aerospace, automotive, etc.

– Effective way to improve design and reduce engineering risks

Van Kuik et al., 2005

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Why is CAE important to Wind Power?

Blade design and

performance

Rotor sizing and

acoustics

Site selection, land and

sea

Tower design and

FSI

Generator and shaft

design

Wind farm configuration

for optimal power

generation

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Blade Design

• Challenges

– Aerodynamic efficiency across expected wind speeds and wind profiles

– Determining integrity of structures made of complex composite materials

– Minimizing noise

– Maximizing strength while minimizing weight

• Benefits of CAE

– Virtual prototyping of initial candidate designs for reduced wind tunnel and full scale testing

• Automation of design of experiments/wind conditions of interest

– Lower design costs

Photo © José Luis Gutiérrez, graphic courtesy of IMPSA S.A., Argentina

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Structural Design

• Challenges– Structural soundness– Wind-rotor induced

vibration– Seismic safety and risk

assurance– Thermal loads on generators

• Benefits of CAE– Determining modal behavior

and non-linear structural characteristics of designs before any manufacturing

– Gaining an understanding of fluid-structure interaction effects during the design process

Photo © Michael Utech

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Wind turbine technology trend

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Energy extractor : wind turbine

WIND (V1) WIND (V2)

Electrical energy caused by wind velocity difference!!

(Efficiency : 16/27)

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Stream tube & actuator disc concept

Stream tube concept

Energy extracting actuator disc & stream tube

Blade element sweeps out an annular ring

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Betz’s limit

Betz limit

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To large wind turbine & offshore wind turbine

32

42ratedp

airrated VDCP

Offshore & Large Scale

• Power ∝ D2

• Power ∝ v3

출력은 풍속의 세제곱에 비례하며 로터 직경의 제곱에 비례함.

따라서 입지조건이 제일 중요하며 풍력발전기가 대형화 될 수 밖에 없는 이유도 이론식에서 설명 가능함.

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Blade basic sketch & modeling

Rotor Diameter

2MW급 풍력발전기 개요

2MW Class HAWT Wind Turbine Concept Design

16

Wind velocities over complex terrain for a proposed wind farm

Wind velocity contours showing the wake effect of one turbine on another

Wind Turbine Siting

입 구

출 구

블레이드

경계조건

ICEM-CFD S/W 사용

Full hexahedral mesh

전체 유동장 계산 격자계

블레이드 주위 계산 격자 (1)

블레이드 주위 계산 격자 (2)

계산 격자계

Item Value

Fluid Air

Fluid Density 1.225kg/m3

Rotational speed 18.7RPM

Rotational direction Clockwise

Turbulence ModelTransition –

Gamma Theta model

계산 조건

Laminar boundary layer

Turbulent boundary layer

Transition region

Transition Model

Laminar Flow

Transitional

Fully Turbulent

Bypass

Transition

Strong influence on mechanical and thermal performance of many technical devices

Effect of Transition Model

wall shear stress 상승.

separation 거동에 영향.

wall heat transfer 상승.

유동 흐름에 영향.

Transition

Transition

Tu Contour

Transition

Wind Turbine Airfoil

유동장 격자 불러오기

작동유체 생성

해석 영역 설정 – General Options

경계조건 설정 – inlet

경계조건 설정 – outlet

경계조건 설정 – open

경계조건 설정 – no slip wall

3

경계조건 설정 – free slip wall

경계조건 설정 – no slip wall

경계조건 설정 – 주기조건

1

경계조건 설정 – 초기조건

모니터링 - Expression 설정

1. Insert→Expression 선택하여 새로운 변수

를 생성한다.

2. 변수 이름을 X방향 힘을 의미하는 force X

라고 명명한다.

3. force X 의 내용에 그림과 같이 입력한다.

force_x()@blade

모니터링 - Monitoring point 설정

블레이드 주위 유선

블레이드 표면 유선

블레이드 표면 압력

블레이드 표면 천이

블레이드 단면 압력분포

기하 모델

유동계산 격자 구조격자

작동조건

하중(압력)유동해석

구조해석

응력 및 변형률(구조변형)

FSI 알고리즘

풍력터빈 블레이드 FSI 해석

해석 모델 유동 격자 블레이드 표면 압력분포

하중 Mapping 단면 속성 단면 속성

46

블레이드 변형 (2-way)

블레이드 단면 유선 (1-way & 2-way)

1 way FSI

1 way 1 way 1 way

2 way 2 way 2 way

블레이드 표면 유선 (압력면)

1 way 1 way 1 way

2 way 2 way 2 way

블레이드 단면 유선

1 way 1 way 1 way

2 way 2 way 2 way

블레이드 단면 압력분포

1 way 1 way 1 way

2 way 2 way 2 way

Thank you