Morphing BlDE Final

8/20/2019 Morphing BlDE Final

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Detailed Design of a Morphable Wind Turbine Blade

Master-1, SMA (Applied Mechanics), Ecole Centrale de Nantes

A Presentation on the

on

04-06-2014

by

Shitij Arora



Motivation

BladeIncrease the efficiency of a WindTurbine by:

1) Improving Aerodynamic

efficiency2) Reducing structural weight

3) Aligning rotor in the direction

of wind Morphability

*courtesy: Wind Energy Essentials



Design Procedure

Step 1Choosing Power for the turbine and Estimating the size of Rotor

0

5

10

15

20

25

30

12345678910

R a

d i u s o f R o t o r i n m e t r e s

Power Rating in 10-1 Megawatts

Variation of Rotor size with Power Rating

I choose this

Power= 0.1 MW

Radius= 9.0952 m

For achieving Betz Limit (CP=0.59), efficiency 80% and Wind velocity 11 m/s

P (in MW)Power Cp eff density pi R U

0.1 100000 0.59 0.8 1.225 3.141593 9.095194 11

0.2 200000 0.59 0.8 1.225 3.141593 12.86255 11

0.3 300000 0.59 0.8 1.225 3.141593 15.75334 11

0.4 400000 0.59 0.8 1.225 3.141593 18.19039 11

0.5 500000 0.59 0.8 1.225 3.141593 20.33747 11

0.6 600000 0.59 0.8 1.225 3.141593 22.27859 11

0.7 700000 0.59 0.8 1.225 3.141593 24.06362 11

0.8 800000 0.59 0.8 1.225 3.141593 25.72509 11

0.9 900000 0.59 0.8 1.225 3.141593 27.28558 11

1 1000000 0.59 0.8 1.225 3.141593 28.76153 11



Design Procedure

Step 2 Choosing a tip Speed ratio (l) for the blade (the ratio between the angular

velocity of wind to the wind velocity) = 6

No of Blades chosen = 3

Airfoil profile: Symmetric profile (no camber) = NACA0018 near hub,

NACA0015 in middle of blade span and NACA0012 near the tip

Taking design value of angle of attack afor which CL/CD ratio is maximum, takecorresponding value of CL from standard tested values for NACA profile

Cldesign 0.65

Alpha 7



Design Procedure

= (2 3 )−(1 )

=

8

(1 ) Vary with span

Step 3 Calculate relative wind angle distribution and chord length distribution along its span

(radius r on total radius R), for maximizing efficiency, is calculated using formula:

=

Blade Twist is given by:

Chord length is given by:



Design Procedure

lambda 6 interval r,i Lambda r,i phi chord twist thickness chord solidity ratio

Radius 9095.19 section-1 0.0001 0.909519 0.0006 59.977 5.857 52.977 0.879 0.0001

Blades 3 section-2 0.05 454.7597 0.3 48.867 2005.665 41.867 300.850 0.05

Cldesign 0.65 section-3 0.1 909.5194 0.6 39.357 2658.595 32.357 398.789 0.1

alpha 7 section-4 0.15 1364.279 0.9 32.009 2673.252 25.009 400.988 0.15

%thickness chord 15% section-5 0.2 1819.039 1.2 26.537 2470.015 19.537 370.502 0.2

rotor area 259880595 section-6 0.25 2273.799 1.5 22.460 2222.976 15.460 333.446 0.25

solidity ratio 0.410 section-7 0.3 2728.558 1.8 19.370 1990.538 12.370 298.581 0.3

section-8 0.35 3183.318 2.1 16.976 1787.636 9.976 268.145 0.35

section-9 0.4 3638.078 2.4 15.080 1614.697 8.080 242.205 0.4

section-10 0.45 4092.838 2.7 13.549 1468.009 6.549 220.201 0.45

section-11 0.5 4547.597 3 12.290 1343.221 5.290 201.483 0.5

section-12 0.55 5002.357 3.3 11.239 1236.408 4.239 185.461 0.55

section-13 0.6 5457.117 3.6 10.349 1144.308 3.349 171.646 0.6

section-14 0.7 6366.636 4.2 8.928 994.264 1.928 149.140 0.7

section-15 0.8 7276.156 4.8 7.846 877.804 0.846 131.671 0.8

section-16 0.9 8185.675 5.4 6.994 785.120 -0.006 117.768 0.9

section-17 1 9095.194 6 6.308 709.768 -0.692 106.465 1

Use the formulas in previous slide to get this!



Why morphability?

What we get??

Best aerodynamic profile possible for a static wind velocity and direction

But what if the wind velocity or direction changes?



Morphability? Okay! but how?

Choose a morphable material for the blade (infinite DOFs in twist)

Choose a mechanism that changes the blade geometry (limited DOF)

Blade Material detailed Requirements:

The blade must be able to twist

It should be strong enough against the wind load

ANTAGONISTIC functional Requirements?

Use COMPOSITES!



Blade Skin Material

Steel reinforcement

Elastomer

Blade skin section

1. I choose blade skin made of high modulus elastomer (silica rubber)reinforced with steel wires (like or unlike tyres)

2. The steel wires give unidirectional strength in the sectional direction of the

blade

3. Elastomer gives ability to take up high degree of twist



Blade Morphing Mechanism

9 proposals for the mechanisms that can be used for morphing the blade

I choose the simplest of all: the TELESCOPIC Mechanism, with 3 concentric

shafts (3 DOFs) for transfering twist into the blade

Each shaft is rotated by a different motor at one end to a precise angular

requirement

Shaft-1

Shaft-3

Shaft-2

The twist at any section of the

blade skin, between two movers

can be found using this relation

=

+



Blade parts

Mechanism: 1 stator (AA2014-T651), 3 movers (AA2014-T651), 3 concentric

shafts (Ti-6Al-4V), 12 bearings (AISI 52100), 2 circlips (M250 Maraging steel)

Stator

Stator Mover-1

Mover-2

Mover-3



Blade parts

Shaft-1: OD 120 mm,

ID 88 mm

Shaft-2: OD 72 mm, ID 50 mm

Shaft-3: Dia 40 mm, ID 50 mm

Circlip [3]

Pretwist in the blade

Double row taper Roller

Bearing [3]

B l a d e s k i n w i t h

p r e t w i s t

B l a d e : m

o r p h a b l e s k i n

9085.7 mm

7066.64mm

4238.08mm

[ 3 ] h t t p : / / w w w . t r a c e p a r t s o n l i n e . n e t



Mechanism Assembly

Stator

Mover-1

Mover-2

Mover-3

Shaft-1

Shaft-2

Shaft-3



Complete Blade with the skin



Simulation of the Mechanism



FE Structural Analysis

Platform: Ansys 12.0 63270 SHELL181 Elements, 189810 DOFs

Material property:

Orthotropic material property for the skinE11= 31GPa

E22= E33= 100MPa,

n12=0.31, n23=n13=0.4995

Aluminum Material: E= 70GPa, n=0.33

Linear Structural analysis

100% mapped meshing



Loads on the Blade

Load on the blade: Dynamic pressure=

+

where = /

Dirichlet BC

The coefficient of pressure

CP for NACA0012 airfoil can

go maximum 5 times. So, I

applied a pressure load

factor of 10 on the

evaluated pressure



Results: Deformations and Stresses

Vector sum Displacements

Vonmises stress



Thank You!

Morphing BlDE Final

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