Wind Energy

39
Aerodynamic Multi-Criteria Shape
Optimization of VAWT Blade Profile
by Viscous Approach
Rémi Bourguet, Guillaume Martinat, Gilles Harran and Marianna Braza
39.1 Introduction
The purpose of this study is to introduce an original blade profile optimization
method in wind energy aerodynamic context. The first 2D implementation
focuses on Darrieus vertical axis wind turbines (VAWT). This class of VAWT
is generally associated with classical aeronautic blade profiles (NACA0012 to
NACA0018) whereas Reynolds number and stall conditions are different in
aerogeneration case [1]. The objectives of the multi-criteria optimization proposed
are to increase the nominal power production, to widen the efficiency
range in order to take into account of wind instability and to reduce blade
weight and by this way minimizing inertial constraint and mechanical fatigue.
39.2 Physical Model
The two main objective functions of this multi-criteria optimization are related
to aerogenerator performances, which means that it is necessary to evaluate
these ones for each profile considered.
39.2.1 Templin Method for Efficiency Graphe Computation
In the context of this first study, power production efficiency is computed
by using a static method introduced by Templin [2] and which consists in a
summation of the global aerodynamic forces applying on the blades during
a revolution of the turbine, considering the polar curve of the profile.
39.2.2 Flow Simulation
The flow is simulated by an unsteady Reynolds Average Navier–Stokes
approach which consists in splitting every physical variable into two parts: