Aerodynamics and aeroelastics of wind turbines - Wind Power Generation and Wind Turbine Design - page 89

CHAPTER 3
Aerodynamics and aeroelastics of wind turbines
Alois P. Schaffarczyk
University of Applied Sciences Kiel, Kiel, Germany .
Aerodynamics and aeroelastics of wind turbines are presented. First, the basic
results of analytical, numerical and experimental work are reviewed, then the
impact on commercial systems is discussed. A short section on non-standard wind
turbines is fi nally included.
1 Introduction
Aerodynamics is a necessary tool for modeling the loads and power output of a
wind turbine. Unlike other related applications such as ship propellers [5] and
helicopters [6], there is no comprehensive and up-to-date presentation of this
important subject. The reader is given a short introduction to current knowledge.
A readable review of, especially, the German efforts during the 1950s and 1960s
was given by Hütter [33]. Hansen and Butterfi eld [26] and Hansen et al. [ 25 ] present
more up-to-date reviews.
It is assumed that the infl ow velocity is more or less stationary, thereby omitting
turbulence as rapid variations above 1 Hz and also neglecting diurnal variation.
These distinctions are meant to be in the spirit of standard regulations, as for exam-
ple given by the IEC (International Electrotechnical Commission) or Germanischer
Lloyd (GL). Therefore no presentation of wake aerodynamics is found in this
chapter. The interested reader may fi nd a review of these items in [64]. This rest of
this chapter is divided into seven sections.
Section 2 gives an account of analytical theories developed largely before the
emergence of digital computers, beginning with the global momentum theories of
Rankine [43] and Froude [23]. Several developments and extensions of these have
emerged only recently. Section 3 introduces the most important development of
the late 20th century: computational fl uid dynamics (CFD). Therefore the reader
should be familiar with the basics of fl uid dynamics [ 2 , 3 ] and viscous fl uid fl ow
[4], together with some of the basics of CFD. Section 4 is devoted to experimental