The Design and Testing of Airfoils for Application in Small Vertical

137 Pages·2006·3.16 MB·English

Master of Science Thesis
The Design and Testing of Airfoils
for Application in Small Vertical
Axis Wind Turbines
M.C. Claessens
November 9, 2006
Ad

The Design and Testing of Airfoils
for Application in Small Vertical
Axis Wind Turbines
Master of Science Thesis
For obtaining the degree of Master of Science in Aerospace
Engineering at Delft University of Technology
M.C. Claessens
November 9, 2006
Faculty of Aerospace Engineering · Delft University of Technology
Delft University of Technology
Copyright (cid:2)c Aerospace Engineering, Delft University of Technology
All rights reserved.
DELFT UNIVERSITY OF TECHNOLOGY
DEPARTMENT OF
AERODYNAMICS
The undersigned hereby certify that they have read and recommend to the Faculty of
Aerospace Engineering for acceptance the thesis entitled “The Design and Testing
of Airfoils for Application in Small Vertical Axis Wind Turbines” by M.C.
Claessens in fulfillment of the requirements for the degree of Master of Science.
Dated: November 9, 2006
Supervisors:
Prof.Dr.Ir. P.G. Bakker
Ir. W.A. Timmer
Ir. C. Ferreira
Dr.Ir. S. Mertens

Preface
This report is the final work of my Master of Science thesis at Aerospace Engineering,
TU Delft. In this report the research that I have did during the 18 months of my
studies in the area of VAWT aerodynamics can be found.
I would like to thank my supervisor Nando Timmer for all his time, the people at the
LTT wind tunnel, Daniel Twigt for reviewing my report and everybody else who has
contributed to my report. Special thanks go out to my girlfriend and my family for all
their support.
Maarten Claessens
Delft, the 2nd of October, 2006
M.Sc. thesis M.C.Claessens
vi Preface
M.C.Claessens M.Sc. thesis
Summary
In recent years more focus is put on the applications of wind turbines in the urban
environment. One of the ways to do this is using a turbine with a vertical axis (a
VAWT). This type of wind turbines is around for many centuries. The modern equiv-
alent which is based on lift producing blades only exists for 30 years. In this period
airfoils for this application have been developed, but still much work can be done in
this field.
During this project a design process is developed with the purpose of improving the
NACA 0018 airfoil, which is commonly used in VAWT turbines. The aerodynamics
involvedinVAWTareinvestigatedtofindthedesigngoalsfortheairfoilcharacteristics.
Furthermore the currently used NACA 0018, which is used as the design reference, is
investigated.
The two main pillars of the design process are the RFOIL program and the VAWT
simulation program. RFOIL is a panel method based program with boundary layer
equations which can calculate the properties of 2D airfoils. RFOIL gives accurate
enoughresultstobeapowerfuldesigntool intheReynolds numberrangefrom300,000
to 700,000.
The VAWT simulation program, written in Matlab, calculates the performance of a
VAWT using 2D airfoil data. The final Matlab program allows to adjust the turbines
geometry, to chose from multiple airfoils and to set a dynamic stall model on or off.
As such 2D airfoil characteristic from RFOIL or wind tunnel tests can be inserted to
view the turbines performance with this airfoil.
M.Sc. thesis M.C.Claessens
viii Summary
Real life turbine
Flow conditions 2D airfoil shape Turbine Performance
simulation results
Design criteria Airfoil design
Airfoil data (RFOIL)
This design process resulted in a final design: the DU 06-W-200. The Du 06-W-200
airfoil is a laminar, 20% thick airfoil with 0.8% camber. The original NACA 0018
airfoil is a turbulent, symmetric airfoil with 18% thickness. To be able to compare
both airfoils wind tunnelmeasurements were performed in the LTT wind tunnelat the
Delft University of Technology. For the DU 06-W-200 airfoil the following conclusions
are made:
• The added thickness of 2% will add to the blade strength and this is reached
without decreasing the performance
• Theaddedcamberof0.8%increasestheperformancewithrespecttoasymmetric
airfoil
• The DU 06-W-200 performance equals the NACA 0018 for negative angles of
attack
• The DU 06-W-200 has a much higher C for positive angles of attack, re-
L,max
sulting in a wider drag bucket
• Deep stall occurs at higher angles of attack with a smaller drop in lift coefficient
• IncontrasttotheNACA0018theDU06-W-200doesnothavelaminarseparation
bubbles which extend over the trailing edge
• The increase in turbine performance at the operating tip speed ratio of λ = 3 is
8% in clean conditions and twice as much when dirty
M.C.Claessens M.Sc. thesis