Optimization of a low speed wind turbine using support vector regression
Date
2009-03
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
NUMERICAL design optimization provides a powerful tool that assists designers in
improving their products. Design optimization automatically modifies important
design parameters to obtain the best product that satisfies all the design requirements.
This thesis explores the use of Support Vector Regression (SVR) and demonstrates its
usefulness in the numerical optimization of a low-speed wind turbine for the power coe
cient, Cp. The optimization design problem is the three-dimensional optimization of
a wind turbine blade by making use of four two-dimensional radial stations. The candidate
airfoils at these stations are selected from the 4-digit NACA range. A metamodel
of the lift and drag coe cients of the NACA 4-digit series is created with SVR by using
training points evaluated with XFOIL software. These SVR approximations are used in
conjunction with the Blade Element Momentum theory to calculate and optimize the Cp
value for the entire blade. The high accuracy attained with the SVR metamodels makes
it a viable alternative to using XFOIL directly, as it has the advantages of being faster
and easier to couple with the optimizer. The technique developed allows the optimization
procedure the freedom to select profiles, angles of attack and chord length from
the 4-digit NACA series to find an optimal Cp value. As a result of every radial blade
station consisting of a NACA 4-digit series, the same lift and drag metamodels are used
for each station. This technique also makes it simple to evaluate the entire blade as
one set of design variables. The thesis contains a detailed description of the design and
optimization problem, the implementation of the SVR algorithm, the creation of the lift
and drag metamodels with SVR and an alternative methodology, the BEM theory and a
summary of the results.
Description
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009.
Keywords
Dissertations -- Mechanical engineering, Theses -- Mechanical engineering