# Presentation: 019530

## Modeling and Analysis of a Wind Turbine Blade with Active Profile Control Using a Shape Memory Alloy 

- By: Jeffrey Mensch

- Background from: http://www.peaceenergy.ca/releases/PEC_press_release_04_07_07/Wind%20Turbine.jpg

## Project Description

- Development of triple rotor blade wind turbine:
- 10-100 kW range
- Choose blade design
- Use active profile control
- Choose shape memory alloy (SMA)
- Compare efficiency of new model with current designs

## Tasks to Be Performed

- Literature search (√)
- Development of design (√)
- Calculations
- Construction of models
- Testing and analysis

## Current Blades

- Made out of graphite coated with epoxy
- Lightweight
- Somewhat flexible
- Can be up to 60 meters long
- Over time/due to strong gusts, can be damaged (blade fatigue)
- Blades stall
- Wind turbine loses efficiency

## Active Control - SMA

- Wind still deforms blade
- Strain gauges attached to blades
- Heating via resistor coils will occur when strain reaches certain level
- SMA blades would go back to original shape

## Active Control – Pitch Control

- Default pitch: about 5°
- Wind speed measured by anemometer
- Pitch can be changed for optimal power output for given wind speed

## Blade Design

- NREL S809 foil chosen (type of Grumman Wind Stream blade) - is in common use for wind turbines

- Source: http://www.nasg.com/afdb/show-airfoil-e.phtml?id=1188

## SMA

| Property | Ni-Ti | Cu-Al-Ni |  | Cu-Zn-Al |  |
| --- | --- | --- | --- | --- | --- |
| % of each element | 49-51%Ni, 49-51% Ti | 13-14.5%Al, 3-4.5%Ni, 81-84%Cu |  | 5-10% Al, 10-30%Zn, 65-80%Cu |  |
| Critical Temperature | -50 to 110 deg. C | -140 to 100 deg. C |  | <120 deg. C |  |
| Density | approx. 6.45 g/cc | approx 7.64 g/cc |  | approx 7.12 g/cc |  |
| Hysteresis (deg. C) | approx. 30 deg. C | approx 35 deg. C |  | 15-25 deg. C |  |
| Problems

 | High reactivity of Ti during preparation (can be averted by preparing in inert atmosphere); high hysteresis (can be lowered by adding Cu); expensive | As ages, loses shape memory properties; can't withstand prolonged high temperatures; after long time as martensite, has aging induced martensite stabilization effect
 |  | 
Needs solution heat treatment to retain shape memory, which can lead to Zn evaporation; As ages, loses shape memory properties; can't withstand prolonged high temperatures; after long time as martensite, has aging induced martensite stabilization effect
 |  |
| Pros | Large pseudoelasticity, can be reused thousands of times, stronger than other SMAs |  |  |  |  |
| Rank | 1 |  | 2 |  | 3 |

## Pros and Cons of SMA Blades

- Pros
- Lasts longer than current blades
- More efficient over time
- Cons
- More expensive
- About 3x heavier (this can partially be avoided by only making the “skin” of the airfoil out of SMA)

## Calculations

- Power Output
- Defined by 1⁄2*CpρAV3
- Cp is the power coefficient (maximum is about .593 according to Betz limit)
- ρ is the air density
- A is the area swept by the wind turbine’s blades
- V is the wind velocity

## Computer Programs Used

- Winfoil
- MATLAB

## Acknowledgements

- Stevens Institute of Technology
- Dr. Siva Thangam
- Joseph Miles
- GISS
- NASA SHARP
- MTSI