DIFFUSER DEVELOPMENT FOR A DIFFUSER AUGMENTED WIND

TURBINE USING COMPUTATIONAL FLUID DYNAMICS

D.G. PHILLIPS, P.J. RICHARDS and R.G.J.FLAY

The University of Auckland, New Zealand

The Vortec 7 Diffuser

Augmented Wind Turbine

Originally designed by Grumman Aerospace in the early 80’s, but built

in New Zealand in 1997.

New Zealand is a

long way from

anywhere!

There is very little

of anything to slow the

wind.

Diffuser Augmented Wind Turbines (DAWT)

Conventional Bare Wind Turbine

L

Secondary Slot

Turbine Blade

Inlet Truss

Structural Inlet Ring

Diffuser Outlet Flange

Inlet Slot Original Vortec 7

Instep

C

Geometry of the Vortec 7

L

Secondary Slot

Turbine Blade

Inlet Truss

Structural Inlet Ring

Diffuser Outlet Flange

Inlet Slot Original Vortec 7

Instep

C

Geometry of the Vortec 7

L

Secondary Slot

Turbine Blade

Inlet Truss

Bullnose

Structural Inlet Ring

Diffuser Outlet Flange

Inlet Slot Original Vortec 7

Modifications

Instep

NoseconeC

Geometry of the Vortec 7

Modelling the as-built Vortec 7

Modelling the modified Vortec 7

Vector Map for the modified Vortec 7

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Disc Loading

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Original Vortec 7

Modified Diffusers

Nosecone and ModifiedDiffusersSmooth Nacelle and ModifiedDiffusers

Wind Tunnel Modelling

CFD modelling of the new diffuser

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Disc Loading

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aila

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oe

ffic

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t Development DAWT

Vortec7 with Nosecone andModified Diffusers

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Disc Loading

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eff

icie

nts

Available Power Available PowerSpeed Up Speed UpBase Pressure Base Pressure

Wind Tunnel CFD Predictions

Original comparison

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-1

-0.5

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0.5

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1.5

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2.5

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0 0.2 0.4 0.6 0.8 1 1.2 1.4

Disc Loading

Co

effi

cien

ts

Available Power Available PowerSpeed Up Speed UpBase Pressure Base Pressure

Wind Tunnel CFD Predictions

Comparison including blockage effects.

Latest Design

CONCLUSIONS•Computational modelling has proved to be a valuable tool in the development of diffuser designs for a diffuser augmented wind turbine.

•The combination of computational modelling, wind tunnel modelling and full-scale testing has made it possible to identify deficiencies in the other techniques.

3rd International Symposium onComputational Wind Engineering

University of Birmingham, England

4-7 September 2000

COMPETITIONTo model the flow around a

6m Cube in a rural atmospheric boundary layer

www.pfconsultants.co.uk/cwe2000