Design of a Vertical-Axis Wind TurbineMUN VAWT DESIGN

Group 11Jonathan ClarkeLuke HancoxDaniel MacKenzieMatthew Whelan

Agenda

Phase 1 Project Goals & VAWT Benefits Configuration Design Selection

Phase 2 & 3 Aerodynamic Analysis Structural Analysis Mechanical Components Economic Analysis

Image Credits: The Telegram

Problem Definition and Goals

Problem Definition Design a VAWT for operation in remote communities in Newfoundland

and Labrador.

The turbine should: Work in conjunction with diesel generators Simple design to reduce manufacturing costs and maintenance issues Produce at least 100 kW of power at rated wind speed Able to account for variable wind conditions in the target area

Project Scope

The project will examine the following aspects of the VAWT design: Detailed structural design and analysis Detailed aerodynamic simulation using computational fluid dynamics Basic vibrational analysis Modelling and engineering drawings of mechanical and structural

components Economic analysis

Why a Vertical Axis Wind Turbine?

Heavy drivetrain components are located at the base Easier to maintain

They operate from winds in any direction No yaw system required

Generate less noise than horizontal-axis turbines

Concept Selection: VAWT Configurations

Two main configurations: Savonius and Darrieus Savonius is drag driven

Low efficiency

Darrieus is lift driven High efficiency

Concept Selection: VAWT Configurations

Two main configurations: Savonius and Darrieus Savonius is drag driven

Low efficiency

Darrieus is lift driven High efficiency

X

Concept Selection: Darrieus Configurations

H-Rotor

Simple

Less Efficient

Complex

More Efficient

HelicalFull Darrieus

Concept Selection: Darrieus Configurations

H-Rotor

Simple

Less Efficient

Complex

More Efficient

HelicalFull Darrieus

Concept Selection: Airfoil Profiles

Extra thickness – increases blade strength

Higher CL,Max for positive angles of attack

Concept Selection: Number of Blades

Capital CostSymmetrical LoadingTorque Ripple

Concept Selection: Number of Blades

Capitol CostSymmetrical LoadingTorque Ripple3 Bladed

Concept Design

Criteria Optimal Choice Alternatives

Configuration H-Rotor Darrieus Full Darrieus, Helical Darrieus, Savonius

# of Blades 3 2 to 4

Airfoil DU 06-W-200 NACA-Series Airfoils

Aerodynamic Design

Preliminary sizing: 320 m2 swept area From wind power density formula:

Analytical analysis using QBlade Developed torque and power curve

Validation using lift & drag equations

Validation using ANSYS CFX

W/m2 = ½ ρavg cP V3

Fl = ½ ρavg A cl W2

Sizing

Validation

QBlade Results

Cut-In Speed:7 km/h

Max Power:130 kW @ 50 km/h

Cut-Out Speed:

94 km/h

Rated Power:

100 kW @40 km/h

ANSYS CFX Setup

Used 2D simulation Sacrifices some accuracy for reduced

computational demand Sufficient to validate QBlade results

Fine mesh near airfoils to capture boundary layer effects Mesh refinement study carried out

ANSYS CFX Results

Average power: 145 kW at peak operating condition Does not account for blade tip losses

Sufficient to validate QBlade results

Dynamic Model Suitable under variable wind conditions

0 2 4 6 8 108

9

10

11

12

13

14

15

Wind Speed Profile

Structural Design

Composite Blade Design E-Glass Fibre and Epoxy Hollow Square Shape Wall Thickness: 50 mm Length: 20 m Fibreglass Layers: 386

Strut Design Hollow Cylindrical Shaft AISI 1045 Cold Drawn Steel Outer Diameter: 36 cm Inner Diameter: 28 cm Length: 7.6 m

Structural Design

Hub Column Design AISI 1045 Cold Drawn Steel Outer Diameter: 0.6 m Inner Diameter: 0.55 m Length: 8.5 m

Tower Design A35 Structural Steel 8 meter lengths Outer Diameter: 3 m Inner Diameter: 2.95 m

Vibrations

At 40 RPM, the aerodynamic and centripetal forces alternate 3 times / cycle

Operating Frequency (@ 40 RPM) = 2 Hz

Maximum Vortex Shedding Frequency = 1.3 Hz

Component Natural Frequency

Tower 3.4 Hz

Struts 2.5 Hz

Blades 3.3 Hz

Drive Shaft 283 RPM (critical speed)

Vibrations

Tower

Blades

Struts

Mechanical Components

Drive Shaft Outer Diameter: 406.4 mm Inner Diameter: 355.6 mm Length: 7 m

Bearings Tapered Roller Bearing

Bore: 406.4 mm Outer Diameter: 546.1 mm Life Span: >20 years

Mechanical Coupling RB Flexible Coupling

Braking and Control

Dynamic braking used to control speed in high winds Dissipates excess power through a network of resistors

External-contact drum brakes used for shutdown Spring-applied, electrically released Fail-safe operation

Compressed air starting system Cheap and reliable

SIBRE Siegerland Bremsen GmbH

Generator

Low-speed permanent-magnet generator Eliminates need for a gearbox Units are typically custom-built for specific applications Rated speed can be as low as 10 rev/min

Sicme Motori Srl

Economic Analysis

Estimated Capital Cost $425 000.00 Quotes

Maintenance Cost per year VAWT Turbine - $10 000.00 Diesel Generators - $86 380.00

Projected Fuel Cost of 2015 $3 630 967.00

Payoff Period ~1M dollars saved annually for an installation of 5 turbines 3 Years

$

Future Work

Full 3D CFD analysis

Structural Dynamic Model

Foundation / Civil Work

Control System Design

Full Scale Testing

Conclusion

Goal: Design a simple, robust vertical-axis wind turbine for use in remote communities

Project goals were met

VAWT design is a viable option to provide power to remote communities

MUN VAWT DESIGNENGI 8926 Mechanical Design Project II

QUESTIONS?http://www.munvawtdesign.weebly.com

Acknowledgements:Thank you to Dr. Sam Nakhla for guidance on structural analysis.