O a method for simulation-based wind turbine blade design

Abstract

SummaryW ind turbines are an important means for the production of renewable energy. This energy, commonly referred to as wind energy, is produced by extracting the kinetic energy from the wind and to subsequently convert it, usually via a rotational motion, to electrical energy. Wind conditions vary from one site to another and the design of a horizontal axis wind turbine depends on these local wind conditions. One of the important aspects of the design of a wind turbine concerns the aerodynamic shape of the rotor blades. The research presented in this thesis focusses on the development of a computational method that can be used for aerodynamic shape optimization.Other aspects -apart from the aerodynamic shape of a wind turbine rotor bladeare also important in the design of a wind turbine, for instance the structural design of the blade. To take this multidisciplinary character of wind turbine design into account, one of the aims of the research presented in this thesis has been that the aerodynamic shape optimization method seamlessly fits into the design process. Moreover, the optimization method is required to be efficient and fully automatic.A suitable method for the parametrization of the wind turbine blade geometry has been investigated. This investigation lead to the choice to use a non-uniform rational basis spline (NURBS) surface for representing the aerodynamic shape of the wind turbine blade. Such a description of the parametrization of the geometry is compatible with computer aided design methods, which eases the incorporation of the aerodynamic shape optimization method in the multidisciplinary design process. A model optimization problem has been considered to determine the relation between the number of design variables that is required to sufficiently accurately represent the design space for solving an aerodynamic shape optimization problem to the number of design variables that is required to realize an accurate NURBS representation of an aerodynamic shape. For the purpose of obtaining a NURBS surface representation of a wind turbine rotor blade, a fitting procedure has been developed. The accuracy of the resulting fit for two representative wind turbine blades is presented. It has been found that sufficient accuracy can be achieved with a NURBS surface described by 13 chordwise sections with 13 control points each.In the present research, objective functions are considered for which the evaluation requires the solution of partial differential equations that govern flow: the Euler equations. Since only for very particular flow configurations an analytical solution of these equations can be found, an approximate solution is computed by solving the discretized equations. Solving the discretized Euler equations requires the discretization of the whole flow domain. During the optimization procedure, the geometry of the rotor blade adapts, i Summary requiring a discrete representation of the new flow domain. To accommodate the change in shape during the optimization, a hyperbolic grid generation me...

Eulerian Method for Ice Crystal Icing

“…The local curvature κ in Eq. ( 22) is calculated in the same way as described in [52]. The curvature will change during the ice accretion process and needs to be updated frequently to obtain the correct value for the curvature κ and the tangential velocity u t;ic of the impinging ice crystals.…”

Eulerian method for ice crystal icing in turbofan engines

“…The aerodynamic flow is computed by an in-house numerical method called MooseMBFlow, which is short for Multi-disciplinary Object oriented Optimization and Simulation Environment for Multi-Block structured Flow. MooseMBFlow is a parallel multi-block Euler/RANS solver which has been extended and applied in research of, amongst others, Jongsma [66], Khatami [68] and Giangaspero [42]. 2.…”

“…The local curvature κ in Equation (5.22) is calculated in the same way as described by Jongsma [66]. It is expressed as…”