Η εργασία αυτή αφορά την διερεύνηση της δυνατότητας μείωσης της ροπής πτερύγισης στην ρίζα των πτερυγίων ανεμογεννητριών, με χρήση μεταπτερυγίων μεταβλητής καμπυλότητας (Μ.Μ.Κ.). Διερευνήθηκε η επίδραση των εξής παραμέτρων στην τελική προκύπτουσα μείωση: είδος χρησιμοποιούμενου φίλτρου, είδος σήματος εισόδου σε ελεγκτή, είδος ελέγχου, γεωμετρία μεταπτερυγίου (μήκος, πλάτος, θέση τοποθέτησης), ταχύτητα τυρβώδους ροής. Οι προσομοιώσεις εκτελέστηκαν σε αεροελαστικό κώδικα ο οποίος αναπτύχθηκε στο εργαστήριο Αεροδυναμικής του Ε.Μ.Π..
(EL)
In the effort of finding sustainable ways to meet the global energetic demands,
wind energy plays a major role. Modern wind turbines with tower top height
at 100m and rotor diameter at 180m produce power of MW in order of
magnitude, while they generate clean energy for more than two decades.
In such machines, the
ap de
ection at the blade's tip exceeds 10% of the
turbine's radius [6.1]. Thus, modern research concentrates on an e ort to
reduce the aerodynamic loads induced on them. One of the most promising
ways to achieve that is by utilizing shape morning techniques (leading &
trailing edge
aps, smart materials) at the turbines' blades.
In this thesis, we assessed the capabilities of trailing edge
aps (T.E.F.)
in reducing the
apping moment at the blade's root. T.E.F. change the
aerodynamic coe cients in the region that they have been introduced, hence
a ecting the blade's loading condition. Nevertheless, because of their limited
dimensions they cannot in
uence the mean value of the
apping moment;
they mostly alleviate the fatigue loads that are produced by gasts (abrupt
changes of the wind speed).
As part of this project we examined the in
uence of several parameters
in the reduction capabilities of T.E.F., mainly: the kind of the elliptic ller
(lowpass, bandpass, bandstop), the kind of the input signal (load, acceler-
ation), the type of control, the
ap geometry (spanwise length chordwise
length,
ap position) and the free stream velocity. Simulations were carried
at N.T.U.A.'s in-house aeroelastic code hydroGast.
One of the pivotal parts of this thesis was complementing hydroGast so
as to simulate the movement of an arbitrary part of the blade's airfoil at a
random position (
ap movement). To achieve that, FOILFS, an aerodynamic
code developed at N.T.U.A.'s Laboratory of Aerodynamics was incorporated
in hydroGast. FOILFS implements the Thin Airfoil Theory to analyze the
in
uence of T.E.F. in 2D airfoils during unsteady
ow conditions.
The results are much promising, indicating that this kind of active control should continue to be investigated in future as it shows great potential for commercial implementation. From the simulations carried out, it followed that an alleviation of 15-20% on the fatigue loads seems well feasible with today's technology.
(EN)
National Technical University of Athens
